THE FOREST FOR THE TREES A systematic approach to restoring native plant communities
THE FOREST FOR THE TREES Wayne Bennett Published by Forest Flora NZ Hakarimata Road, RD 1, Ngaruawahia, New Zealand 3793
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Author’s dedication To Mark for curiosity and enthusiasm and to Jan for perseverance and focus.
First published in 2019 by Forest Flora NZ, Hakarimata Road, RD 1, Ngaruawahia, New Zealand 3793 Copyright © 2019 Wayne Bennett. All photographs by the author. A catalogue record for this book is available from the National Library of New Zealand. Kei te pātengi raraunga o Te Puna Mātauranga o Aotearoa te whakarārangi o tēnei pukapuka. ISBN: 978-0-473-45475-3 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of the publishers and copyright holders.
Contents Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 The forest for the trees . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Homo sapiens: The ultimate ecosystem engineer . . . . . . . . . . . . . . . 11 A reference ecosystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Weeds: unfair competition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 A community of plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 A plan of attack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Examples of restoration projects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Clearing the slate: The weeds encountered . . . . . . . . . . . . . . . . . . . . . . 75 Native species: Itâ€™s a jungle out there . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 Recommendations for more reading . . . . . . . . . . . . . . . . . . . . . . . . . . 121 Appendix 1: Evaluating a restoration plan and monitoring its implemention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 Appendix2: Forming and working with community groups . . . . 124 About the author/acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 126
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Something to aim for: rich diverse lowland forest in the Coleville Range. 4
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n a warm spring weekend in the early seventies, a group of students and staff from Te Aroha College wrenched a pile of native seedlings from the mountain and planted them on a sunny, dry, northâ€“facing slope at school. None of us could identify any of the species but were nevertheless terribly surprised and disappointed when not one plant survived the week. The surprising thing is that we ever expected them to. In the following years I have explored the craft of forest restoration on my own and surrounding properties and, later, riparian restoration projects, residential developments, farm sustainability initiatives and urban gully restoration projects. Watching these projects progress, especially when the outcomes were unexpected, has been a valuable learning opportunity. I have slowly come to recognise plants as components of a dynamic community and participants in an interbreeding population. I now realise it is not just about picking appropriate species for the site, but also about maintaining and restoring natural patterns and processes. This guide explores this way of thinking and demonstrates how much more can be achieved if we stop looking at a collection of trees and instead see the processes that make it up and the natural patterns found there. The search for the seeds of remnant native species in the district and the attempts to propagate them have been an ideal opportunity to gain understanding of the
local species and the plant communities they are a part of. Widespread landscape planting of native species along waterways, roads and otherwise unmanaged areas has become increasingly popular. This valuable work might be seriously enhanced by careful observation of remnant natural areas, an understanding of the dynamics of the plant communities and propagation exclusively from parent plants of known, natural and local provenance. Even in a country as small as New Zealand, the constitution of native plant communities is extremely variable from place to place, not only due to climate and other habitat variables, but also isolation. Even individual plant species vary across the landscape. This natural variation deserves protection as much as the species themselves. Taking lessons from the natural world is the key to more authentic and sustainable planting projects and is the theme of this guide. My work includes setting up Forest Flora in 2006 to guide and support ecological restoration here in the Waikato. We are working towards propagating the plants native to this part of the country and understanding the communities they come from. I also coordinated a community organisation, Ecosourced Waikato, after 25 years of working as a taxidermist; a very different approach to preserving nature. I sincerely hope the legacy I leave through my present work overshadows the taxidermy.
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Coastal forest near Whitianga in the Coromandel Ranges. 6
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The forest for the trees A systematic approach to establishing native plant communities
There are certain parallels between taxidermy and restoring ecosystems, or at least in the way that people have tried to restore them. Because an ecosystem must not just look like one, it must function like one as well. A taxidermist can faithfully reconstruct the form and appearance of a live pheasant, but nobody can reassemble the live bird one organ, tissue or cell at a time. To live and function as a live bird, every part of its structure must work simultaneously. In the same way, a community of plants is not static, but is continually renewing itself. There are processes going on all of the time that give a natural system the ability to adapt to changing conditions and the resilience to cope with threats. Think of the stuffed pheasant that maintains the appearance of a live bird if it is maintained and is kept dry and dusted, but which cannot grow new feathers when the old ones fade, cannot fly to avoid a predator and cannot reproduce to populate a favourable area. Even the cells that make up every part of a live bird have a short life and are constantly being recycled. In the same way, ecological restoration is about restoring the unseen processes that make an ecosystem work and that sustain it, not just creating the illusion of a forest. It takes a little more care to set up but reinstating natural processes and faithfully following natural patterns results in a more authentic, resilient and self–sustaining ecosystem.
ike many Kiwi kids growing up on farms, my uncle had a brief flirtation with taxidermy. He enrolled in a correspondence course at the Northwestern School of Taxidermy in Omaha, Nebraska, and, as part of the course, stuffed a pheasant. What he did next is the stuff of family legend. He planted the pheasant in the paddock just within shotgun range of the garden fence. Over lunch, my grandad spied the pheasant and, without a word, made for the back door. As his right hand extracted two home loads from his cartridge belt hanging on its nail on the door, his left hand closed around the barrels of his prized Webley & Scott side–by–side shotgun standing in its usual place by the door. Grandad crept silently down the path and, screened by the dunny, checked to see if the magnificent cock bird was still there. Now, the rules of engagement for pheasant shooting require the bird to be in flight before it is shot, but my grandad had lived through a depression and two world wars. He was more pragmatist than purist. Grandad released first the right barrel, then the left. Feathers flew, exposing not only the wire and woodwool armature but the deception as well. As the feathers floated to the ground, he slowly lowered the gun. Grandad swore till the day he died that he saw the bird jump just before he fired. Grandad was convinced it was a live cock pheasant, but it was just an illusion. Having worked as a taxidermist for myself 25 years, I am often reminded of that story when I work with native plants. 7
THE FOREST FOR THE TREES Thankfully, unlike with a stuffed pheasant, we can reassemble an ecosystem one species at a time or even one individual at a time. This is because we can simulate the natural processes and cycles on which they depend until those processes are restored. Because ecosystems are dynamic and continually changing, ecological restoration doesn’t aim at a particular end point, but rather aims to reinstate natural patterns and restores natural processes so that an ecosystem can continue to develop and adapt. This book explores the best processes that ensure that a planted site functions like an ecosystem. Natural processes allow an ecosystem to regenerate and even transform itself as conditions change, and to expand into new areas when conditions are favourable. When we focus on restoring a natural plant community, the processes that are particularly important are those that determine a species’ presence and relative abundance. These processes include: • Pollination • Seed production • Dispersal • Competition within and between species • Succession and the modification of the environment by plants The patterns we are most interested in understanding and replicating are both spatial and temporal; they include: • The structure of a forest community, the combination of species and the range of strategies for growth, survival, reproduction and dispersal. • The cycle of disturbance from events like storm, flood and fire through a succession of plant communities as plants modify the environment. • The pattern of distribution of each species across the landscape. This may be historical, that is, as a result of dispersal since the last great climate change; or environmental, as a result of the species’ ability to thrive and compete in a particular environment.
Ecosystems are much more than plants: Healthy, functioning systems are a complex interplay between animals, plants, fungi and other microorganisms. But plants, producing energy through photosynthesis, drives each ecosystem. You could say plants are the very beginning of an ecosystem. Although plants may rely on other components of an ecosystem for nutrient cycling and dispersal, they can establish on their own, which is why we usually begin restoration projects with flora. Building a healthy plant community is an important first step towards ecological restoration. Sadly, not all past human intervention in New Zealand’s ecosystems can be reversed. Extinctions have taken place that can never be undone and, despite some remarkable successes with exotic mammal exclusion and control, it is doubtful whether many introduced species can be completely eliminated any time soon. Just planting or revegetating an area falls short of what could be achieved. Revegetation is commonly tackled using quick–growing native shrubs, but there is no attempt to facilitate succession to longer–lived species or a complex forest structure more resilient to disturbance or weed invasion. Revegetation, then, is a short–term measure. It is possible, in the right circumstances, for a site planted with quick–growing native shrubs to develop into a complex and resilient native forest, but unless the seed sources are nearby, it is much more likely to be overtaken by weeds as the shrubs approach the end of their life span. We can never completely reverse human impacts on ecosystems, but every small step we can make to reinstate natural patterns or processes contributes to ecological restoration. Even the use of the local shrub twiggy coprosma (Coprosma rhamnoides) for landscaping in my garden contributes to maintaining it within its natural range and helps restore the natural dispersal pattern by 8
THE FOREST FOR THE TREES providing what we call a “stepping stone” for pollen and seeds. When planning ecological restoration, it is helpful to regard plants as members of dynamic, interbreeding populations and competing components of diverse plant communities. As they grow, plants profoundly alter the environment, removing water and nutrients from the soil, depositing organic material and altering its physical structure. Plants also increase humidity and moderate rainfall, wind, frost and desiccation by intense sunlight. The most significant effect on the environment is the reduction of sunlight reaching the ground. There may be a thousand times as much light in the full sun as under the shade of a multi–layered forest, and a thousand times as much energy available for photosynthesis. This means that the seedlings of many plant species cannot grow under their parents, vacating the space in favour of a succession of species better adapted to the modified conditions. For this process to proceed, it is necessary to ensure the right species are found on the site and are able to disperse throughout it. This might happen entirely with the initial planting, but, more likely, additional planting will be necessary as the conditions change in favour of successional species. It is worth the time to plan a plant community carefully, focusing on processes rather than just plants. The consideration moves from “what species will thrive in these conditions?” and “what will they look like when they reach maturity?” to “how will this combination of plants compete with weedy species that may also establish on the site?” and “will the species planted aid dispersal and so help overcome fragmentation in local plant populations?” Also ask yourself, will the project enhance habitat for native birds, invertebrates or fish? Will the species planted naturally regenerate or will they create the conditions favourable to other native species? And can they disperse throughout the site or to nearby ones?
View of the canopy of regenerating lowland forest. The camera was set for 1/80 sec at f/8.
View of the undrerstorey in the regenerating lowland forest. The camera, mounted on a tripod was set for an exposure of 2.5seconds at f/5.6. This is 320 times as sensitive as was needed for a picture of the canopy. The plants adapted to these shady conditions are very different to the plants which initially colonise bare ground on a site like this. It is not easy for those of us who gain our energy from eating other organisms to really appreciate just how important sunlight is to green plants.
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Homo sapiens The ultimate ecosystem engineer
omo sapiens originated on the plains of Africa and spread from there to become one of the most widespread species on the planet. Imagine our ancestors setting out on a journey of discovery to unknown places. This might have happened from time to time, particularly crossing the Bering Strait or the Atlantic to reach America, or out across the Pacific. Most of the time though, it must have been small movements as populations increased, the ice retreated after the Last Glacial Maximum, allowing access to new habitats, and the technology to be competitive in new environments developed. In his book The Future Eaters, Tim Flannery describes how our ancestors broadened their ecological niche, changing from scavengers and gatherers to top predators. He discusses how change was slow at first, allowing prey and competitors to adapt and how, as change accelerated, the ability of ecosystems to adapt gradually fell away. Development of language, the use of tools and early agriculture must have all contributed. As our ancestors spread into new environments, they would have had to compete for food with existing predators and learned to cope with predation themselves. It is reasonable to expect that predators were displaced and prey animals threatened. Whenever any species thrives, it becomes an attractive resource for predators, parasites and pathogens, which will thrive along with it. In turn, these predators, parasites and pathogens contribute to maintaining a balance and make
it difficult for a single species to dominate an ecosystem. Competition for food resources also helps maintain a balance and prevents any one species dominating an ecosystem. History certainly records the vulnerability of early man to wolves, lions, locusts, smallpox and plague. Over time, these threats have receded as we developed strategies to combat them. The development of agriculture brought a new ability to increase our population. The retreat of ice following the last glacial period allowed spread into America, leaving only the Pacific Islands to be colonised as the technology for navigation across this last frontier developed. As people spread, we took with us dogs, cats, chickens, rats and mice. We also took coconuts, taro and, as agriculture developed, a whole range of crops. Some of these we planted over vast areas. Some have naturalised and now compete in local ecosystems where they have become environmental weeds. Kiwifruit, for example, is a natural climber from China, which, grown in orchards in the warmer parts of the New Zealand, now establishes from seed and dominates small patches in recovering native forest. As the human population grew and technology developed, we gradually ceased to be a small part of the natural world. As resources became scarce, we developed pioneering technology to exploit new resources. Whaling changed from a local coastal resource into a worldwide industry, almost extinguishing some species until 11
THE FOREST FOR THE TREES economics and an environmental conscience reined it in. Not only do humans occupy every continent and most islands of any notable size but the rats, cats and plants we took with us have also colonised wherever they have followed. One thousand years ago the islands of New Zealand were the last remaining significant landmass yet to yield to humans. The archipelago’s isolation had protected a unique biota, but that isolation also made it vulnerable when settlement began. New Zealand’s natural plants and animals had evolved in isolation not only from humans, but a range of browsers, predators and plant pathogens, making them vulnerable when new invasive species arrived. Take the low reproductive rate of some of our birds. While this is a distinct advantage in an ecosystem without mammalian predators, it becomes a serious disadvantage once mammalian predators are introduced. Flightless birds, presumably with a competitive advantage in a pristine New Zealand, also feature disproportionately among the ranks of the extinct. Since the first human settlers arrived here less than 1,000 years ago, 41 species of birds and seven plants have become extinct. These figures, though, don’t tell the whole story. Extinct plants leave very little evidence of a past existence and the scientific cataloguing of plants and animals is still incomplete. Human impact is not limited to the extinction of species. Whole ecosystems have been lost or are threatened. Some ecosystems which are naturally uncommon have been further reduced by human activities. These may be found on uncommon landforms like shell banks or geothermal stream sides, but even once– common ecosystems like seabird and marine mammal–influenced sites are now seriously affected. Ecosystems, once very common, particularly on valuable agricultural land, have also been highly modified and are at risk.
Deforestation has been carried out on a grand scale with little regard for the possible consequences. Wetlands have often been drained for farmland, and although there are small representative examples preserved, few intact remnants of river or wetland margins exist as a guide to their restoration. In most countries there is a strong correlation between the size of the area, how productive the ecosystems are—this is often closely related to the climate—and the number of plant species found there. Larger areas and more productive ecosystems have more species. Other factors, like how variable the habitats are, also influence the number of species. Charles Darwin noted the vigour of introduced plants when he visited New Zealand in 1835 and predicted that many would in time replace native species. In the last 200 years, as he predicted, more introduced plant species have naturalised than are native to these shores. We now have twice as many plant species as were here before European settlement. If the general rule is to apply, then without intervention, there are likely to be further extinctions. These result ultimately from small, isolated and low–density plant populations suffering the effects of inbreeding, genetic drift or chance fluctuations in populations, reducing the competitiveness of the species, further reducing the population and increasing isolation and ultimately spiraling into extinction. Typically, this can take many generations, which, in the case of trees may mean many decades or even centuries before the effects are observed, but the process is now well underway. Through acclimatisation, translocation and accidental introductions, humans have seriously altered the natural distribution of numerous plants and animals and probably fungi and other microorganisms as well. Not only have we significantly altered the landscape, we are now told we may even have altered the climate on a global scale. 12
THE FOREST FOR THE TREES As we approach the end of the first millennium of human habitation in New Zealand, we find ecosystems have been fragmented and species have been lost. Other species, birds like kiwi, kakapo and kaki (black stilts) and plants like nau/Cookâ€™s scurvy grass (Lepidium oleraceum) and wood rose (Dactylanthus taylorii) are increasingly dependent on active conservation for their survival. There is no indication that the extinctions of species have come to an end, yet we have no idea how dependent we are on those ecosystems or what benefits those lost species held for us. As well as the contribution natural areas make to the quality of our lifestyle and recreational opportunities, there are a myriad of ecosystem services they provide; things like erosion control, moderation of flood events, provisioning of clean drinking water and maintaining a favourable climate. There is a growing realisation that we may have gone too far and we need to restore native ecosystems wherever it is still possible. Millions of native trees and plants are planted every year in a valiant effort to reverse the losses. Are we achieving all we can by doing this?
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Development has removed natural ecosystems from a significant proportion of the planet, isolating populations and interrupting natural processes. Here, forestâ€“clad Mt Pirongia overlooks highly modified farmland
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A reference ecosystem Learning from nature
f we are looking at planting a new forest or even a small area of native plants, it is helpful to consider what might happen on a hypothetical newly–emerged volcanic island. The way native vegetation will establish when the island first emerges has many lessons for anyone planting natives in a barren area. This is especially true if there is an intention to restore the natural processes which manage such an area and make the project more self– sustaining. The spores of mosses, liverworts and lichens are tiny and blow in the wind. These organisms don’t need soil and are the first to establish. They are small and lack the structures that transport water, minerals and sugars. Lichens in particular help to break down rocks, hold the resulting sediment and contribute to the first organic humus. The first vascular plants to arrive tend to be those with very good dispersal mechanisms. They might produce large amounts of sweet, brightly–coloured fruit, or vast quantities of tiny, wind–blown seeds. It is no coincidence that these species tend to grow rapidly in a range of soil conditions and tolerate exposure to wind and frost, but to grow well, they also need full sun. Some native grasses and herbs fall into this category, as well as some of our taller plants and shrubs like the two flax species, mountain flax (Phormium cookianum) and New Zealand flax/harakeke (Phormium tenax), as well as manuka (Leptospermum scoparium), kanuka (Kunzea spp.), koromiko (Hebe or veronica spp.) and karamu (Coprosma spp.).
With no competition from taller trees, these species have a field day, making the most of the sunlight to quickly grow to maturity. And while they produce seed at an early age, these plants may not live long and are likely to suffer eventually as taller vegetation grows around them. Other plants might arrive at the same time as the early colonisers, but, being slower growers, are less obvious at first. Some of these may not tolerate the exposed conditions and will not survive until more shelter is established. Others need deeper soil or other plants to grow over and perch on. Slower– growing plants may, however, be more durable and better tolerate the shade created by surrounding plants once they establish. In this way, a succession of species will result. If the island is big enough, there will always be some disturbance where the earliest arrivals will have an advantage and persist. Other plants climb or scramble over their neighbours, perch up in the canopy or tolerate very low levels of sunlight on the forest floor. As more species reach the island, a more complex forest develops. But the number of species cannot increase indefinitely. As more species establish on the island, competition between them becomes stronger and as suitable sites and resources are limited, populations of each species will become sparser, making them less viable. In time the number of species will reach an equilibrium based on the size of the island, the proximity to the mainland and the productivity of the site. 15
THE FOREST FOR THE TREES Developing a virtual reference ecosystem This would be easy if we had plenty of healthy, unmodified natural areas persisting in our modified lowland landscape. All we would need to do would be to visit a similar site, measure it carefully and copy it. And we are particularly fortunate in New Zealand, because as the last significant landmass to be colonised by our species, there are still trees which predate the first human settlement. Early Polynesian settlers brought few new plants from the tropics and what they did bring needed cultivation and protection to survive. This means that despite the broad– scale transformation of the landscape over the last 200 years, there is still evidence of the nature of primeval ecosystems to be found in the range of species persisting in forest remnants. There are also early settler accounts of the landscape and evidence in the form of pollen in lake sediments and in wood, resin and leaves buried in peat, providing clues about the species’ mix once found there. Herbarium records and species lists for local reserves are useful sources of information. Lists of appropriate species for selection of local habitats have been prepared by local authorities, government organisations and restoration consultants. These are sometimes associated with cultural requirements for the species recommended and can be a useful guide, but should not replace first–hand experience of local natural areas. Forest fragments not only provide clues about the species mix that might be found on a particular landform, but also help us understand the specific tolerances and vulnerabilities of each species and tell us where they are most likely to thrive. Carefully studying a range of sites of similar landform may also help to piece together clues about the succession of a site from early colonising species to more mature forest. The remnants of kahikatea (Dacrycarpus dacrydioides) forest found scattered across
The same principles apply not only to oceanic islands, but to fragments of lowland forest now isolated by areas of developed or productive landscape. Planting native areas can provide stepping stones for the dispersal of plants and animals, effectively bringing the forest–fragment “islands” closer to each other and to the “mainland”. Without providing these stepping stones, existing small lowland forest fragments risk losing species over time. As species disappear from one fragment, then another, they are at risk of ultimately disappearing from whole regions in the longer term. This not only makes these remnants less resilient because of the reduced range of species, but also risks the loss of genes found only in these regions. As a forest or other natural area matures, the environment changes, favouring a succession of species over time. By observing natural areas of varying maturity, we can begin to understand this succession and use the knowledge to help either replicate or restore the processes necessary to establish a new plant community. Nowadays, in many particularly heavily populated or developed areas, the landscape has been so modified that no single site can provide a clear picture of the nature of a natural ecosystem. We have to survey a number of sites, modified in a variety of ways and at different times, to begin to understand the plant communities that may have established on similar habitat without human change. We call these sites reference ecosystems: models for the recovery or reconstruction of a natural ecosystem. Surveying reference ecosystems can help build up a comprehensive picture of the patterns and processes which make up the plant community. Planting a site with native plants without reference to this kind of information will result in something more reminiscent of a stuffed pheasant than the live bird. We might find it useful to refer to such a comprehensive picture as a “virtual reference ecosystem”. 16
THE FOREST FOR THE TREES river valleys and lowland plains throughout the country frequently lack the full complement of understorey species once found there. In those forest fragments where grazing animals were once present but have since been excluded, we often find a small number of species with a different range of plants in each site. This might simply be due to the reduced number of species able to survive on such a small site. It might also be the result of few understorey shrubs surviving the period of grazing due to their greater size, unpalatability or inaccessibility, then rapidly reproducing to fill the site once the grazing animals had been excluded. In addition to the loss of some native species from small forest fragments, there is also the possibility that some native species from other parts of the country have naturalised as a result of injudicious planting nearby. This, sadly, is not uncommon. The best way to know when native plant species have been introduced is to observe a number of sites and note what is common to all or many of them. A few native shrubs have been very popular to plant, and these are the ones to be careful about. Some of the species to watch are tarata (Pittosporum eugenioides), kohuhu (Pittosporum tenuifolium), karo (Pittosporum crassifolium), kapuka (Griselinia littoralis), akeake (Dodonaea viscosa) and pohutukawa (Metrosideros excelsa). Some genera are represented by different species around the country, so care should be taken with Hoheria, Sophora and Kunzea, among others. This highlights the need to visit and observe a good range of such sites to construct a reliable virtual reference ecosystem that accurately reflects the natural distribution of native plant taxa. If we were to merely observe which species grow quickest on the site in the first years after planting, we would fail to understand how the environment changes as the plants grow, how rigorous competition between species can affect the composition, and how long a plant will live for.
Plants that grow quickly like karamu (Coprosma robusta), New Zealand flax/ harakeke (Phormium tenax), or manuka (Leptospermum scoparium) often either donâ€™t live long, are intolerant of shade, or sometimes both. These species tend to be replaced in time by other, longerâ€“lived or more shadeâ€“tolerant species. They are found on recently disturbed or inhospitable sites but not in dense forest. Constructing a useful reference ecosystem will require observing of remnants of varying ages to get a clearer idea of how a forest might continue to change over time and to better understand the range of trajectories a site might potentially follow. Propagating and growing native plants can also provide useful insight into the dynamics of a natural plant community. Seed collection is a great way to sharpen observational skills in natural areas and an incentive to regularly revisit sites. Observing plants as they germinate, grow to maturity, flower, disperse, regenerate and compete with others, helps us understand their vulnerabilities and tolerances. Watching the same plants over a lifetime can make us more aware of their interactions, influences and interdependencies. Characteristics like shade and drought tolerance can become second nature to the observant gardener, especially if the temptation to modify the growing conditions is resisted and naturally occurring dry areas, shade, poor drainage or infertile conditions are seen as an opportunity rather than a threat. A virtual reference ecosystem will provide guidance about the plant species required for the project, the conditions they grow in, how numerous they might be and where they fit in the successional sequence.
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Weeds: unfair competition Control needs to be integrated with planting
Wandering Jew (Tradescantia fluminensis) is a good example of this. A small, insignificant species in its native Brazil, wandering Jew has spread to damp, shady areas in New Zealand, wherever it can elude frosts. Because of its ability to smother the ground as well as lowâ€“stature shrubs and seedlings, this little creeper has a significant influence on the other species found with it. Along the Waikato River, crack willow (Salix fragilis) and Japanese honeysuckle (Lonicera japonica) are prevalent because these plants can spread vegetatively despite the presence of wandering Jew (Tradescantia fluminensis). Recent attempts to curb the vigour of this weed by introducing some of the organisms that keep it in check in Brazil, need time before they work. As well as replacing the native plants that may be unique to an area, weeds are undesirable for another reason. A natural plant community consists of a combination of species with complementary strategies, each one filling a unique niche and reducing direct competition for resources with the neighbours. This is no accident. Strong competitive pressure has selected those individuals and species that are advantaged by adopting a sufficiently different strategy. Their unique strategy allows them access to resources while reducing direct competition with other species. So in a forest we may have not only the canopy trees basking in the sunlight but also shrubs tolerant of the shade beneath.
here are now more species of naturalised exotic plants (weeds) growing in New Zealand than native plants. According to the New Zealand Plant Conservation website, www.nzpcn.org.nz, there were 2,422 native vascular plant species and 2,552 naturalised vascular plants in 2013. Not all of these are considered invasive yet, but their invasiveness can take time to become apparent. All naturally regenerating, they have the potential to displace native species and disrupt natural patterns. We might expect native plants adapted to local conditions to be more competitive than any introduced plants adapted to a foreign environment, but this is often not the case. Isolated islands are less exposed to recruitment of new species, so the plants there â€” and here â€” have not been subjected to the same level of competition and consequential selective pressure that those on a less isolated site might have been. And plants in their natural habitat are likely to have pathogens and grazers specifically adapted to them. If the plant species is well established there, these pathogens and grazers will help contribute to maintaining an equilibrium. When these plants are transferred to another country, there is the possibility of transferring them without these pathogens and grazers and so without the handicap. The foreign host plant, then, has a competitive advantage over local species, which may have a complete suite of predatory organisms keeping it in check. 19
THE FOREST FOR THE TREES On a site dominated by weeds, this fitting together of complementary strategies is compromised, often resulting in the domination of a few species. This may lead to fewer species and lower biomass for a given area and an impaired habitat for native animals. Replacing the weed–infested site with a natural plant community, based on careful study of a healthy ecosystem, can contribute not only to the resilience of local native plant populations in the area, but also ensure more nutrients and carbon are sequestered as a result of both greater productivity and biomass. Disturbed areas where weeds have established are likely to remain dominated by weeds without some intervention. Lack of nearby seed sources and the vectors for dispersal may account for this, or our native forest species may be well adapted to succeed native colonising species, but may not have developed strategies to out–compete introduced ones. An important precursor to restoration planting is the suppression of those weeds dominating the site, long enough to establish a native plant community. In areas where a rich forest is the natural order, the plan is always to establish a tall, dense plant community, better equipped to resist further weed incursions. Just as the native species dominant on the site will change as the project progresses, so will the weeds present. Quick–establishing weeds like inkweed (Phytolacca octandra) and wild turnip (Brassica rapa sub sp.sylvestris) can be a real problem soon after planting, but as the new native seedlings establish, these will be shaded out and more shade tolerant., taller or climbing weed species now become the biggest threats. The aptly–named bindweed (Calystegia spp.) is intermediate in this regard. This species can be a real problem for young plantings. Although it may not be apparent at the time of preparation or planting, bindweed can move in quickly from either spreading stems
or seed to become the most prevalent species on a site. Without control, bindweed (Calystegia spp.) will bind the emerging top leaves of cabbage trees/ti kouka (Cordyline australis), causing the growing tip to rot. Young shrubs and trees can be bent over and deprived of energy–bringing sunlight. But eventually, these young trees and shrubs will grow too tall and dense for the new spring growth of this deciduous climber to emerge over the canopy, and it will cease to be a threat. There is no altruism in native plants and although successive species modify the environment, facilitating ecological succession — the process by which the structure of a biological community evolves over time — they can, on occasion, also interrupt this process. Pohuehue (Muehlenbeckia australis), for instance is a vigorous climber, creating such a dense canopy that few native plants will thrive in its shade and some control may be necessary to establish a more complex plant community. Pohuehue is, however, an important part of a plant community, sustaining both butterflies and birds, so although its control may be necessary, its elimination is not. It would be nice to think we could easily eliminate all weeds before we start a project, but in reality, we have to prioritise on most projects, assessing the potential of each weed species to compromise the planting. This will not only vary from species to species, but also from site to site. To use our previous example, wandering Jew (Tradescantia fluminensis) will be a serious threat on damp, shady, frost free sites, but on dry sites, very shady sites or where frost will always be a factor, or a combination of these, it may not grow with sufficient density to be a problem. Weediness will only be one factor in the equation. Species that are not yet common, but have the potential to spread, will be a high priority. Royal fern (Osmunda regalis) is well established in some Waikato wetlands and beginning to establish in others. 20
THE FOREST FOR THE TREES Where it is not yet well established, it will be a high priority to control. Where royal fern is well established, control may be uneconomical. The situation can be complex. Willows (Salix spp.) compete with native plants for sunlight. The roots of grey willow (Salix cinerea) can also form mats that trap sediment and allow them to progressively spread into what would otherwise be deep, open water around lakes. To their credit, however, they can be an aid to reinstating natural plant communities. The shade which willows generate may suppress grasses and light–dependent weeds more than it adversely affects woody native shrubs, giving newly–planted natives a competitive advantage. Shelter from frost provided by leafless willow branches can be sufficient to help establish plants like mahoe (Melicytus ramiflorus) or pukatea (Laurelia novae–zelandiae), which would otherwise not survive until other native species are well established, progressing the succession process by several years. Many weedy tree species, like willows (Salix spp.), walnuts (Juglans spp.) and wattles (Acacia spp.) may provide habitat for important lizards, invertebrates or epiphytes. Removing these trees might possibly do more harm than good, so it may be an option to retain them until alternative native habitat is established. On other sites, removing these weedy seed sources may be a higher priority. Exotic grey willow (Salix cinerea) and gorse (Ulex europaeus) will grow taller in many wetlands than any native plant species, meaning they will never be out–competed, so will need to be removed at some point and require ongoing control to prevent their return. Successful weed control is never a one–off event or instant makeover; it requires a long– term strategy. An effective plan will need to address the specific conditions at each site, taking into consideration the particular threats of each weed species, as well as how common it is and how quickly it might spread. Weed control will need to be integrated with a planting programme: ultimately, the only
sustainable way of managing the issue long term. Weed–control strategies are usually a combination of several different approaches. Herbicides are a valuable tool, but must be handled appropriately by suitably qualified people. These may be applied by various types of spray application, by wiping on, by injecting into wood and by pasting onto cut surfaces. A few herbicides are selective for certain groups of plants, but ineffective on others; these can be useful for achieving good control while avoiding damage to desirable plants. Triclopyr–based herbicides like Grazon are ineffective on grasses and sedges, but do a good job of controlling many broadleaf weeds. In some sites, retaining the exotic grasses can be a big advantage, because they suppress taller broadleaf weeds. Most weed–control programmes require repeat applications to ensure complete coverage while avoiding excess runoff where it can do harm. New products and formulations arrive on the market all the time, so it is important to keep abreast of changes and try herbicides on a small scale before attempting widespread use. Several herbicide–free approaches to weed control are also worth considering. A range of weed–control strategies is explored later in the section on preparing and implementing a restoration plan.
THE FOREST FOR THE TREES
THE FOREST FOR THE TREES
A community of plants Planting for succession / patterns in time and space
very native plant in New Zealand today has a unique competitive advantage in the ecosystem in which it evolved. Plants which may seem vulnerable in today’s environment are, in fact, well adapted to the environment in which they evolved, or they would not be here today. Putting together a planting plan is a challenging task. It requires good knowledge about the form a forest might take on a particular site, but also an understanding of the trajectory the plant community might follow during the transition from bare ground to mature forest. A native forest is made up of hundreds of different plant species. It is so complex that the distribution of plants can appear almost random, but in reality is far from it. Unraveling the factors which locate plants where they are to be found is a big help when it comes to restoring or reconstructing a forest. There are three factors that determine what plant is found on a particular spot: Firstly, a species must be able to disperse to that spot; secondly, it must be able to grow competitively on that spot; and thirdly, if it is to establish a viable population in the vicinity, it must have enough of its species sufficiently close by. The ability of the species to disperse to that spot or, more appropriately, the probability of dispersal, most commonly depends on parents growing on suitable habitat nearby. Our native plants have developed ingenious strategies for dispersing, investing heavily in these mechanisms and indicating just how important spreading its seed is to a plant.
This section covers: • colonisers • canopy trees • understorey • climbers, scramblers, lianas and epiphytes • ground cover • protecting biodiversity • ecosourcing • ecosourcing in practice • animals, fungi and bugs Species like manuka (Leptospermum scoparium), kanuka (Kunzea spp.), rata, akatea and pohutukawa (Metrosideros spp.) have large numbers of tiny seeds that can be blown long distances in the wind. Others, like kauri (Agathis australis) and rewarewa (Knightia excelsa), have fewer, larger wind–blown seeds which develop larger seedlings. These have developed a wing or sail to aid dispersal. Others, particularly plants growing near water, like kowhai (Sophora microphylla) or the sedge family, have seeds that float and can be dispersed to suitable new habitats during floods. Birds are an extremely useful resource for plants focussed on dispersing seeds and are the preferred vector for many of our trees and shrubs. Seeds sometimes have brightly– coloured and energy–rich coatings, inducing birds to swallow them and carry them to a new site. Other plants produce a sticky coating or little hooks to their seeds, allowing them to hitch a ride on animals. When designing a planting plan for a restoration project, it is 23
THE FOREST FOR THE TREES helpful to have some idea of how the plants disperse seeds. This is a useful guide to how closely related the original population of the site may be to other populations in similar habitats nearby or further afield. For a plant to be found on a site naturally, it is essential for it to have a way to disperse there, though that doesn’t guarantee its success. In a garden, a plant can be watered, fed and weeded to ensure optimal physical conditions are met and that competition from weeds and other plants doesn’t shade it out. It is a jungle out there and in natural areas plants have to fend for themselves. Charles Darwin referred to this as the struggle for life. Seeds of many different species may all disperse to almost the same spot, but stiff competition between the seedlings will determine which will grow to maturity and produce seeds of their own. Minor differences in the physical characteristics of similar sites will suit different plant species. These might be things like the slope, aspect, soil characteristics or microclimate. The site itself will be changing continuously as trees grow around it, then die or fall. The species best equipped to capitalise on a particular location will vary along with this change in the canopy and surrounding plants. Having a good appreciation of the tolerances and vulnerabilities of the plants likely to naturally disperse to a site will be an advantage when selecting plants for a project, and again when planting out, because that is the best clue to what is most competitive there. Reference ecosystems are so useful because they are a guide to the species most likely to thrive on any particular spot. When trying to decide the appropriate plants for a site, I find it useful to research reference ecosystems that not only indicate appropriate species, but also help with understanding the conditions they grow in and how they grow. When choosing species for a site, it may seem like a good idea to select from those naturally
found in more adverse conditions, as they will certainly thrive in the better conditions. We could look at the swampy lake margins and choose the flaxes, swamp coprosmas and manuka (Leptospermum scoparium) in the waterlogged soil there to plant on the slightly better–drained higher ground, where these would certainly thrive. But if we look over a naturally vegetated area in similar circumstances, these are not the species we find there; we find a different suite of plants growing further up the slope. The reason for this becomes apparent when the plants have grown big enough to compete with each other for space. Flaxes will thrive in either very wet or very dry soil, but fail when taller vegetation starves them of sufficient sunlight. The problem is compounded when willows (Salix spp.), walnuts, wattle (Juglans spp.), alder (Alnus spp.), gorse (Ulex europaeus) and blackberry (Rubus fruticosus agg.) also enter the site and compete with the planting. The wetland species have quite open foliage and are too short to out–compete these weeds, so the weeds will require ongoing control. We need to identify the appropriate combination of species for this more productive landform. Finding good reference ecosystems for such areas is not easy because it is such ideal farmland, but is ultimately the only sustainable solution. Small pockets of native vegetation can be found along rivers and streams in inaccessible parts of farms. These are fascinating and so valuable. They show us that further back from the lake, as distance increases and drainage improves, the wetland species will merge with taller, but stunted, kahikatea (Dacrycarpus dacrydioides) and a range of understorey shrubs, ferns and herbs. The forest grows taller, the number of species increases and the light levels at ground level decrease as growing conditions improve, creating an environment much less open to weed invasion. 24
THE FOREST FOR THE TREES There is a third factor determining the species found on a site: For a species to persist, there must be a viable breeding population in the area. In sexually reproducing populations, genes are recombined in a unique combination for each new individual. Where a population is sufficiently large and good dispersal reduces the possibility of breeding between close relatives, this results in an ongoing supply of unique individuals. Competition between them leads to a healthy population well–adapted to the site and able to adapt to environmental changes as time goes by. If the population is too small, too sparse or where dispersal is poor, leading to breeding between close relatives or self–pollination, valuable genes can be lost from the pool every time they are recombined in individuals from a new generation. This can lead to weakening of the population and possibly its eventual local extinction. This may not be significant in the time frames we normally consider, but restoration begins to extend our time horizons. It is prudent to consider long–term considerations. Planting native plants on a site replicates the natural dispersal to that site. This natural dispersal has been seriously depleted as natural areas become increasingly fragmented and isolated. In other words, we are intervening to replace a natural process which may no longer occur. This replication of natural dispersal is of utmost importance because plants benefit from dispersal in two significant ways. Dispersal to new sites ensures that progeny is less likely to compete with parents and siblings for resources like sunlight, water and nutrients, and more likely to settle on and take advantage of new habitat. Dispersal also increases the effective population size, reducing the probability of breeding between close relatives, which leads to loss of genetic diversity and a less viable population. Under ideal circumstances, native plants might establish naturally. In modified environments, though, this increasingly does
not happen because of competition from weeds and the lack of nearby seed sources. If a natural plant community is to develop, intervention may be necessary. If resources don’t allow planting an area densely enough to exclude weeds, there are methods of replicating natural dispersal other than planting trees and shrubs. Possible approaches include spraying seed mixed with water on a site, laying manuka (Leptospermum scoparium) or other seed–bearing branches on the bare ground, or packing seed into clay balls called seed cakes, and spreading them around. Alternatively, one of the most cost effective ways to spread seed is to plant just a few plants somewhere on the site and allow them to mature, set and eventually disperse seed naturally over successive seasons. These methods can be a low–cost strategy for introducing new species into an area, but in order to tackle weedy situations well, or establish native plant cover and exclude weeds in a reasonable time, it is usually necessary to plant a dense matrix of native plants with the potential to out–compete at least some of the weeds. Often, even if there is a natural seed source nearby, the conditions at the restoration site mean they can’t establish because of dense grass, ground cover or deep shade. Natural dispersal relies on wind, water or animals to convey seeds to new sites. This process isn’t random; it is related to the nature of the various vectors involved and diminishes with distance from the source. Plants are expensive and planting, time consuming. To make the most efficient use of resources, a planting strategy must not only replicate natural dispersal, but also replicate or anticipate the influence of competition between species to maximise survival, provide protection from weather and offer the best defence from weeds. In other words, for each location, choose the species, from those likely to disperse to the site, which is most likely to thrive there. 25
THE FOREST FOR THE TREES If we were planting a group of plants whose survival was only required until a canopy was achieved and if there was no possibility of weedy trees establishing the site, we could plant any possible combination of plants that would grow in the physical environment found on the site. But there is value in establishing a planting project with longâ€“term prospects. These will often be threatened by alder (Alnus glutinosa.), elder (Acer negundo.), willows (Salix spp.), wattles (Acacia spp.) and walnuts (Juglans spp.), strong competitors with our native plants. When we start to contemplate the competition between species of plants, the importance of establishing a natural plant community, composed of species with a wide range of complementary strategies, begins to emerge. In order to maximise the benefits of any planting project, it is important to use a range of plants with a variety of growth strategies. Recreating a plant community with a range of different root systems results in better use of nutrients and water as well as better bank stability than can be achieved by any one species. A community made up of plants with a range of strategies for accessing sunlight will ensure more complete use of this resource. A range of dispersal strategies helps ensure the availability of birds to disperse seeds and pollen, as well as food for these vectors year round. Again, the best way to make sure that this happens is to closely copy the variety of species found in a natural plant community growing in a similar situation. Many projects aim to plant on only one occasion, into bare ground, limiting the possible outcome to species adapted to open ground. Few projects are likely to progress of their own accord from bare ground to mature plant communities, with healthy animal populations and few if any exotic species. This would take decades at least. Many of the species necessary to provide resilience in a plant community may either not be available at the time of the initial planting
or may not thrive until sufficient canopy cover is established. If planting is done on only one occasion, there is always the opportunity for a second organisation or individual to take over the project and continue the work, introducing species that were not appropriate until some forest cover was established. Research shows those projects which have staged planting over time progress further towards the goals than oneâ€“off plantings. This means there will be some benefit from an initial planting project and more benefits as the project is enhances and matures. Communities of plants must contain a range of species with complementary strategies so they can take advantage of the resources available and collectively outâ€“compete invasive species. They must also have the diversity to be able to respond to rapid changes like disturbance, as well as gradual changes as trees grow and new species establish. These are the processes which drive a natural plant community, give it resilience and make it sustainable and unique. Without them, a planting project might resemble a city park or garden rather than a natural system, requiring ongoing weed control and plant replacement. For the purpose of replanting natural areas, I find it useful to group plants into five categories; colonisers, canopy trees, understorey, climbers and epiphytes, and ground covers. Not all of these categories contain species suitable for planting into bare ground, but in time, they all contribute in their own unique way to a healthy, resilient plant community. It is important to note that the distinctions between these five groups of plants are to some extent arbitrary, but are still useful to consider when selecting species to plant because they help ensure a range of growth strategies in the new plant community. Colonisers The most important species to plant on bare soil are colonising plants. These typically 26
THE FOREST FOR THE TREES grow fast, are tolerant of a wide range of environments and are effective and early dispersers. These characteristics make them ideal to take advantage of disturbed sites in the wake of fires, flooding and storms, not to mention human activities. This group does not tolerate shade from competitors well and as other species establish, fails to thrive. Despite this intolerance, there will always be margins and possibly newly– disturbed areas where they persist and have an important role to play. Later in the book we look at a number of common colonisers and discuss how they perform in this role. The ongoing presence of these species is important because they will add resilience to the site by being some of the first to establish after a future disturbance of any kind. Toetoe (Austroderia spp.) and karamu (Coprosma robusta) are uncommon in mature bush but if present, initially dominate a slip or riverbank after flood disturbance. On some very exposed sites, this group of plants may be the only one to thrive until establishing some shelter. On other sites, species from other categories may establish along with the quick–growing colonisers, but will not dominate the site until later in the successional sequence. Once a canopy of these shrubs is well developed, the conditions may be suitable to introducing new species. If a site is planted with only quick–growing shade–intolerant species, particularly if they are short–lived like manuka (Leptospermum scoparium) or karamu (Coprosma robusta), the site will likely eventually revert to weedy trees and climbers. Longer–lived and taller trees are needed to give permanence to the project and exclude these weedy species. Colonisers modify their environment, making the ground beneath too shady for their own species, but suitable for other categories of plants. Not all colonisers modify the environment in the same way, and although many provide shelter and shade, which may advantage later successional species, others may significantly
slow down succession. The choice and placement of colonisers can have a big effect on the restoration trajectory. Take karamu (Coprosma robusta), which grows very quickly, providing significant shelter and shade within a few years, but dies off at about 10 years, progressively allowing slower, more shade–tolerant species space to expand into. This means using mainly karamu (Coprosma robusta) as a coloniser will result in early dominance by a healthy range of canopy species. Kanuka (Kunzea spp.), on the other hand, also grows quite quickly once it has become acclimatised to the site, but continues to thrive for a century or more if not shaded out, so will establish a tall canopy sooner. The shade it causes, however, will slow down the establishment of later succession trees, possibly by decades. This results in a much taller, more resilient canopy in a short time, but delays the establishment of a rich, diverse canopy. Sedge species, like those of the Machaerina genus, will grow well in ground that will eventually also support a tall swamp forest dominated by kahikatea (Dacrycarpus dacrydioides) and pukatea (Laurelia novae– zelandiae). These sedges will colonise the site quickly and for a time suppress the establishment of woody species. Most Machaerina species, however, are intolerant of shade and nearby trees will in time inhibit their growth sufficiently for seedlings of swamp forest trees and shrubs like kahikatea (Dacrycarpus dacrydioides), pukatea (Laurelia novae– zelandiae), matai (Prumnopitys taxifolia), swamp maire (Syzygium maire), turepo (Streblus heterophyllus) and a selection of small–leaved coprosmas to take hold. Colonisers can both enhance and delay the succession process. Canopy trees Some forest canopy species may arrive along with the colonisers and begin to establish as soon as a disturbed site begins to recover. 27
THE FOREST FOR THE TREES But unlike the colonisers, they have developed a strategy of building a tall, durable platform to place their leaves above the plants around them. Growing strong, durable wood takes time and resources, so this group of plants may be slower to establish and may not set seed until securely established in the top layer of the forest. This is a variable group, tolerating varying degrees of shade, wind, frost and soil conditions. Some, like kahikatea (Dacrycarpus dacrydioides) and totara (Podocarpus totara var. totara) can be planted in quite exposed conditions. Others, like tawa (Beilschmiedia tawa) and pukatea (Laurelia novae–zelandiae), may need the shelter of surrounding vegetation on all but the most sheltered sites. Canopy trees live long, grow tall and each spreads over a wide area, making a considerable contribution to a project. When mature, tall native trees compete successfully with weedy tree species and make large sites more suitable for a good variety of understorey species. To plant a site exclusively in canopy tree species can be a viable restoration strategy, at least as a first step. Trees should be planted sufficiently close to each other—4m to 6m apart—to eventually form a closed canopy. It may take time to achieve the closed canopy, so weed control before planting and in the early years will be particularly important. This might be much cheaper than intensive planting, particularly on very large projects and where the incidence of weed inundation is lower. After a canopy is established, understorey species will still be required for a healthy, resilient plant community.
be very stable, sheltered from wind and frost and the desiccating effect of a harsh summer sun. Tolerance of adverse conditions always comes at a cost, so plants in this group that do not waste resources on coping with wind, frost and desiccation, may have more energy for growing wood, leaves or seeds. This would put them at an advantage in a stable, sheltered forest situation. The great diversity of shade–tolerant understorey shrubs tend to be fussier than other groups of plants about the right habitat. Some shrubs, like putaputaweta (Carpodetus serratus), kotukutuku (Fuchsia excorticate) and pate (Schefflera digitatata) grow along damp stream margins, but not where they may be subjected to prolonged flooding. Heketara (Olearia rani) and rangiora (Brachyglottis repanda) grow on drier, steeper slopes, but need some shade if they are to be protected from drying out too much in the summer. Toropapa and other species of Alseuosmia prefer dappled shade, sloping ground and just the right amount of water and aeration in the soil. Because plants in this group are specialists, including a wide selection of them in any planting plan is important so the best species can be selected and planted in each spot. Colonisers, on the other hand and, to a lesser extent canopy trees, are generalists, thriving on a wide variety of habitats. Understorey species can be more particular about their environment, some thriving only in a narrow range of conditions. Riparian margins tend to be ideal agricultural land, so those plant species acting as specialists in these areas are becoming less common and may disappear from large sections of the landscape if they are not included in restoration projects. Being a member of this group does not automatically disqualify a species from being planted in open areas. Identifying those shade–tolerant species that have a good
Understorey If they are ever to have the opportunity to place their leaves in full sunlight, the shrubs that make up an understorey need to be able to grow well and set seed in the shade. The environment under the canopy of a forest, while deficient in energy–giving sunlight, may 28
THE FOREST FOR THE TREES chance of survival in exposed conditions for a particular site will help progress the succession to a mature plant community. This will ensure that by the time trees have achieved a canopy, there will be mature shrubs, setting seed and beginning to establish a dense understorey. Despite being shade–tolerant to varying degrees, most plants will grow better and in particular produce more seeds if they have good sunlight, so planting species from this group in the early stages of a project, if the site is suitable, is a distinct advantage. Plants cleverly only grow leaves when there is sufficient light to make it worth their while. You may have noticed that as trees and shrubs die, leaves in the darker, lower parts are not replaced. In a similar way, when a nearby tree falls, surrounding trees and shrubs quickly grow new leaves from parts newly exposed to sunlight, but previously too shady to have previously been economical. I have often seen the growth of new branches and leaves lower down on a trunk once a light gap has occurred in the canopy above and of course we are all familiar with the atrophy of leaves and branches on the lower trunk as a tree grows. One implication of this phenomenon is that plants with the ability to grow leaves in shady conditions will allow less light to pass onto the ground below, because they intercept even the low light levels found in shady places. Plants that tolerate—and therefore create— more shade are very useful for improving the efficiency of an ecosystem, taking up nutrients otherwise left in the soil, sequestering carbon and providing food and habitat for animals, fungi and microorganisms. The opportunities for weeds to establish are further reduced because there are fewer resources available for them. The first three groups of plants; colonisers, canopy trees and understorey shrubs, will make up the initial planting plan if the project is on open ground without existing woody vegetation. These will start to create the conditions suitable for the other plants more
typical of a mature forest. Two other groups will eventually contribute to the health of a plant community, but will usually be reserved until there is an established canopy. These are species that perch up in trees or climb over them to access sunlight and those that tolerate the low light of the forest floor. They conserve energy by not attempting to access high light levels in the forest canopy. Climbers, scramblers, lianas and epiphytes Climbers, scramblers, lianas and epiphytes take advantage of trees to get their leaves up into the sunlight. This is an important group because the climbing members are well suited to occupying space that becomes available when a tree falls. Some of these, like Parsonsia species and the native passionfruit (Passiflora tetrandra) will establish in quite open sites, but may be best left until the trees establish well, so young tree seedlings are not overwhelmed by them. Others, like the perching astelias and some ferns, seem to grow almost exclusively on trees. Small specimens of these can be tied up or nested in trees, particularly if the medium of decaying leaves sometimes found in the forks of branches, which they naturally grow in, can be replicated. Sphagnum moss or natural fibres can be used to help contain a root ball and get these plants established sooner than would otherwise happen. Alternatively, sometimes epiphytic species can be induced to grow and set seed on the ground, particularly on rocky outcrops or steep banks. Hopefully, natural dispersal by birds or on the wind will then establish them up in the trees as suitable habitat develops. Of course, if these epiphytes are naturally growing close to the site, they may disperse there by natural processes, with no intervention being necessary. Ground cover Ground–covering ferns, sedges and herbs use the last of the light reaching the forest 29
THE FOREST FOR THE TREES floor. This is important because it helps exclude potentially invasive exotics that might otherwise use this resource. Ensuring these species are present contributes to carbon sequestration and they may also have an important role in the life cycle of other plants, animals, fungi or other organisms which contribute to the stable functioning of the ecosystem. Few of these species will be found in pasture or even in forest remnants where animals have been grazing and sheltering for decades. Ferns, because their spores are so small and numerous, can, in the right conditions, disperse over great distances to complete their precarious life cycle. Some of these persist along rural drains and these remnant populations are a valuable repository for their re–establishment once forest conditions are returned to the landscape. The process can be accelerated and conditions suitable for weeds can be reduced if the natural dispersal is aided by the transplanting of a few specimens from nearby remnant populations. Although these five groups of plants complement each other and so to some extent avoid direct competition, there is no suggestion of altruism or even collaboration here. It is simply the result of the ongoing competition for resources, in which the species best adapted to accessing these resources is favoured. Plants are like children: you can’t have favourites. Selection of appropriate species must be based on the role each plays in the community.
limited geographic range, there is a strong link between places and the unique biodiversity they support. By protecting natural areas and the biodiversity unique to them, we are helping to slow the loss of biodiversity caused by human activity. If biodiversity is lost, we cannot simply replace it with animals and plants from elsewhere, because a unique aspect of the natural world will have gone for all time. Closely following natural patterns and restoring natural processes in order to achieve sustainability makes good sense for economic reasons, but there are other benefits as well. Every locality in the world has a unique habitat: a unique combination of climate, soil, slope and water. Every area also has a unique combination of animals and plants native to it. The type of forest that develops on river terraces or wetland margins will be very different to the type of forest that develops on hill slopes or ridges. Here in New Zealand, much of the land suitable for farms, houses and roads has been cleared and developed, leaving more natural plant communities mostly on steep hillsides. This means that the forests of the river terraces, peat lake margins, low hills and gullies are represented only by seriously depleted remnants and sometimes only by occasional individual trees and shrubs. Many of our native trees have separate males and females and on highly developed farmland and urban areas, these may be too far from others of their species to set seed, so are effectively excluded from the local breeding population. Whenever we plant trees, shrubs and other plants, we have the opportunity to overcome this isolation by establishing stepping stones to help restore the natural dispersal of pollen and seed. This natural dispersal is important to protect the original distribution range of our native plants, also to ensure genetic diversity specific to that location is maintained. When populations are small or breeding between close relatives is common, genetic drift and
Protecting biodiversity Biodiversity is short for ‘biological diversity’. It describes the variety and diversity of all life on land, in fresh water and in the sea, including the places or ecosystems where they live and the genes they contain. • From the Ministry for the Environment website, mfe.govt.nz/issues/biodiversity/ Because unique genes, species and ecosystems are naturally found within a 30
THE FOREST FOR THE TREES inbreeding can result in loss of both genetic diversity and viability. Because pristine native plant communities are now rare across farmland and in urban areas, restoration projects have an important role to play. It is still possible to reconstruct, from the few plants remaining, the natural structure of these rich diverse forests for future generations. But the few remaining plants are slowly disappearing and so are the opportunities to restore in these areas. By embarking on a restoration project we have the opportunity to protect the remnants of the original biodiversity of the area, which might otherwise be lost, but only if, when propagating plants, we are careful to replicate and restore natural dispersal patterns and processes.
Kanuka has also recently been divided into a number of distinct species and there are other species requiring a closer look which may result in similar divisions. This feature of the natural world is as valuable to us as castles and cathedrals are to the heritage of our European kin. The natural distribution of genes and species provides vital clues to New Zealandâ€™s unique biological history and it would be a shame to lose it. The propagation of native plants from local provenances for ecological restoration is called ecosourcing. The term is a distinctively New Zealand one, but other countries also try to propagate from local provenances as much as possible to protect local natural character. There is an inherent paradox in ecosourcing, which means it will always involve some compromise. If it was always possible to propagate plants required for a project from parents close enough to naturally disperse to the site, there would probably be no need to plant there, because native plants would establish naturally. Ecosourcing means the best practical alternative to natural dispersal. This requires careful judgment to assess the best compromise in each situation. Ecosourcing works best when seed can be collected and grown for a specific project from the closest practical source. A source suitable for propagation for ecological restoration purposes will be clearly natural and well away from native plants, which may have been planted there by somebody. There must be a reasonable population at the site â€” preferably 20 or more adults â€” in order to reinstate a population with a gene pool with the level of diversity which might once have been found on a site. Because many sites may have only one or two individuals bearing seed, it may be necessary to collect seed from a number of nearby sites in order to replicate the natural level of diversity. Specific propagation for a project takes time and requires good forward planning.
Ecosourcing We are sometimes reluctant to accept that the little trees we plant will one day grow up and become sexually active. But the trees and shrubs we plant will introduce their genes into the local gene pool, so it is really important to take precautions. If we are to protect natural patterns of distribution, our dispersal of plants to new restoration sites should mimic natural dispersal as closely as practicable. Not only is the natural range of plant species limited to certain areas, but the distribution of some genes within those species is restricted as well. Darwin noticed that species commonly varied considerably across their natural range; one phenomenon that led him to suspect species have not been constant and unchanging since the time of creation. The geographic distribution of different characteristics within a species has been recorded many times and sometimes this has led to the division of one species into several. When I went to school, we recognised three species of native kowhai. Later, a careful appraisal of one of these species, Sophora microphylla, led to the recognition of five distinct species, each with its own natural range. 31
THE FOREST FOR THE TREES It may in some cases be possible to source, from a specialist nursery, plants which have already been propagated from natural populations with the origin carefully recorded. This will be a distinct advantage, but requires a good deal of trust. Plants must come from a nursery with a good reputation for quality ecosourcing. There is another compelling reason for taking ecosourcing seriously. This has become apparent since the appearance of kauri dieback disease in the Waitakere Ranges and Northland. This serious threat to kauri (Agathis australis) occurs only in parts of its natural range. At the time of writing, it is absent from the Waikato, Coromandel Peninsula and Hunua Ranges. It would be extremely unwise for site managers in these places to source kauri plants from areas where kauri dieback is established, as the possibility that the disease was introduced to natural areas by a nursery and spread through wellâ€“meaning planting cannot be discounted. Australian rainbow skinks (Lampropholis delicata) are well established in the northern part of the North Island. Unlike native skinks, they lay eggs, often in potting mix, which means these are dispersed around the country with the distribution of plants. Pests and diseases can be well established in an area before concern is raised and the movement of plants is curtailed. Restricting the movement of plants is a sensible precaution, particularly for native ones destined for restoration projects, not only to prevent the spread of these particular pests, but also for others which have not yet been identified. For ecosourcing to be successful it requires good understanding, not only on the part of the nursery producing the plants, but also by the plant purchasers. It goes without saying that it is very important to ensure that species, subspecies and varieties of plants ordered from a nursery must be ones which naturally occur in the area the project is located. It is also important when ordering plants that enough
time is allowed for the collection of seed at the right time of the year, then allowing time to grow the plants well before they are to be planted. Restoration includes the replication of natural processes which may have been interrupted in some way. In the days before human settlement in New Zealand, if a site was cleared of plants by fire or flooding, native plants would have reestablished on the site by natural dispersal processes. The most common plants to find their way to the site would be those growing closest and those best at dispersing their seeds. For most of the species arriving there, some genetic diversity would be apparent, just as we see variation in a group of people. Genes which are common locally would predominate and other genes common in the species elsewhere may be completely absent. Ecosourcing tries to replicate the dispersal which might have once happened naturally and avoids the dispersal of genes which wouldnâ€™t have occurred naturally without intervention. This is important to protect biodiversity, that is, the range of genes, species and ecosystems on this planet. This diversity has developed in part as adaptations in a specific location, the result of selective pressure. The link between biodiversity and location is strong. Due to human activities, biodiversity is continuing to reduce as more natural areas are cleared, or as local plants and animals are replaced by introduced ones. We cannot increase or replace biodiversity, only slow down the loss. Biodiversity can only be increased by evolutionary processes, which are notoriously slow. By replicating natural dispersal, we do the best we can to avoid further loss and maintain whatever is unique to a specific place at that location. Ecosourced plants should always be accompanied by a record of the origin or provenance and preferably the number of parent plants contributing to the line. It is very difficult to ensure that ecosourcing has 32
THE FOREST FOR THE TREES been done well without actually visiting the seed–collection site at the time of collection. It can be helpful to discuss seed sources with the nursery staff and gain some assurance from their level of understanding about ecosourcing and knowledge of the collection sites.
it possible for a plant to achieve satisfactory dispersal with minimal investment in sugary, brightly–coloured fruit. This would allow the plant to put more investment into the size or the number of seeds, improving viability or quantity of seedlings. Throughout the year, there are species which produce ripe seeds, making collection and reconnaissance a year– round activity.
Ecosourcing in practice Ecosourcing generally involves seed collection from populations of native plants which are known to be naturally occurring and not planted or naturalised from previously planted stock. This is possible in most parts of this country because of the short period of human habitation here. In some parts of the world, humans have been modifying the landscape and translocating plant species ever since the ice retreated 10,000 years ago. In other parts, human impact has been even longer. With increased planting of native plants in recent years, it is becoming more difficult in some places to find genuinely natural areas. Those plants which have become less common due to clearing, grazing and weeds are the very ones that are most important to find and from which to collect the seeds. Despite this, there will be small remnants of native vegetation wherever land is not so intensively managed. Many hills are well endowed with native bush, but the truly valuable sites are riverbanks and other “wasteland” areas that have the appropriate plants for lowland river, wetland and lake margins. These are useful places to collect seeds and to study carefully in order to construct reference ecosystems to aid the planning of planting projects. Plants growing out in the open away from tall bush are likely to seed more heavily than those found growing in a healthy forest. Although autumn is the time of year when mature seeds are most commonly found, any plant species which can produce out–of–season fruit has a virtual monopoly on birds for seed dispersal. Out–of–season fruit may have even made
Propagating from seeds or cuttings Plants are commonly propagated from seed for ecosourcing and restoration purposes. Seedlings are unique individuals, so propagating from seed helps preserve the diversity in a population. By collecting seed from a number of individuals at a location, we not only sample the diversity held within those parent plants, but possibly many others that may have pollinated their flowers. When a restoration project is isolated from surrounding natural areas, care must be taken to ensure a viable population of each species results, to avoid the effects of inbreeding. The requirements to achieve this will be variable, but a founding population of no less than 20 individuals and the potential for the population to grow to between 50 and 500 is commonly accepted as necessary. Providing linkages to nearby natural areas may be the best way to achieve a viable population size. Many of the species required for restoration projects may simply not have sufficient seed– bearing individuals from a single site to achieve this. Collection and propagation of cuttings from other plants in the area not producing seed will not only help increase a founding population, but also potentially sample genes which may otherwise be missed. In cases like this, a wise propagator will return plants to the seed collection site to help ensure the parent population remains viable. Animals, fungi and bugs Nothing in nature exists in isolation: Plants interact with animals, fungi and bugs in a variety of ways, some of which are well 33
THE FOREST FOR THE TREES understood while others are not. Many of our plants rely on birds or other animals to disperse pollen and seeds in exchange for nectar or fruit. Without this mutual arrangement, many plant populations would suffer from inbreeding and have no way to access new sites to occupy. Small invertebrate animals, fungi and microorganisms all have a role to play decomposing dead plants and animals and recycling nutrients. Many restoration projects will have nearby healthy natural ecosystems and these organisms will be able to disperse into the project well. Some projects, however, may be on sterile ground, well away from natural areas. In this case, in the absence of more specific guidance, one option is to transfer a little soil and leaf litter from a healthy forested area nearby to the ground of a planting project, during the life of the first plants planted. Specific advice about establishing animals, fungi and bugs should be sought from appropriate experts. Our native birds are pretty good dispersers, so given suitable habitat, many nearby species will establish themselves and thrive as the project matures. If the planting plan follows natural patterns, there will be ample food for healthy populations of these birds. Our bird species, however, are not well adapted to cope with mammalian predators, so ongoing control of rats, stoats and cats may be a big help. All native birds are protected under the Wildlife Act (1953) and subsequent amendments. This means any translocation of native birds must be done under the careful supervision of the Department of Conservation. Not all restored sites are suitable for translocations of protected birds, so if reestablishing native birds is to be an objective of a project, this should be discussed with appropriate experts before selecting a site.
essential to most terrestrial ecosystems, fungi also play a pivotal role. Many fungi have developed a strategy of decomposing dead material, some have adopted techniques for living off living organisms while others have developed a mutual arrangement with green plants. We refer to this third group as a mycorrhizal association and it seems to be common in a majority of plants. This arrangement has benefits for both partners, the fungi have access to sugars produced in the leaves of the plants and the plants gain access to a super fine network supplementing their roots. The mycorrhizal association particularly assists plants growing on the margins of suitable habitat, on dry, poorly drained or low nutrient soils. Of course the association has to be with suitable fungi which are well adapted to the dry, poorly drained or low fertility conditions. In addition to being adapted to the conditions of the site the fungi are often specific to a limited range of â€œhostâ€? plants. Plants grown for restoration purposes are more likely to have appropriate mycorrhizae if their growing medium is hospitable to these fungi, plants are grown in the vicinity of natural areas where spores are able to colonise or soil from around the parent plants is incorporated into the growing medium.
Summary Any restoration project must have clearly defined objectives so we know what we are trying to achieve and can measure how well this has been done. The natural world has been perfecting the patterns and processes which make up ecosystems for a very long time. We are well advised to observe carefully and emulate the solutions which nature adopts. This is done by surveying reference sites. When designing a planting project, consider the role of each species, how it gains resources and affects the plants around it. Include a variety of species with a range Mycorrhizae (Literally rootâ€“fungi) of complimentary strategies, collectively Just as plants as primary producers are contributing to a stable community. 34
THE FOREST FOR THE TREES
A plan of attack Preparing and implementing a site–specific plan
aving looked at the things that might influence the success of a project, the next step is to decide on strategies intended to achieve the objectives. This section details a range of strategies, activities and tools that might achieve those goals. The structure of this section is intended to form a useful template for a restoration plan. Some of these details might be usefully included in such a plan in order to clearly specify what is to be done, how it is to be done and when.
This section covers: • Site objectives • Site assesment • Developing a strategy • Weed control strategy – manual / mechanical control – knapsack sprayer – motorised sprayer – drilling and injecting – cutting and stump pasting – mowing, slashing and mulching – aerial spraying • A systematic approach to weed control • Protection from animals • Propagating and sourcing of plants • Planting day • Plant placement • Putting the plant in the ground • Timing • Maintenance and supplementary planting • A timeline • Trials, monitoring and recording
Objectives and priorities Restoration planting has a wide range of benefits, and there are many reasons for doing it. Native forest, particularly lowland forest, is now uncommon in populated areas and that rarity alone gives it value. Forests growing along waterways take up nutrients from the soil and keep them out of the water, where they lead to possibly toxic algal growth. These forests also shade waterways, keeping the water cool and consequently more oxygenated, something that is also important for native fish and for some insects. Native forest can screen unsightly structures like industrial sites or quarries too. There is no better way to soak up carbon dioxide than to store carbon in the tissues of native trees and shrubs, the plants that grow over or perch in them, the animals that live in them and the soil in which they grow. I’ve mentioned how restoring natural areas creates natural stepping stones to aid the
dispersal of both native plants and animals. This will become more important as our changing climate alters the natural range of native plants and animals. It is not a coincidence that when restoring a native forest, authentically reconstructing the natural patterns and restoring natural processes is the most effective way of achieving all of these objectives. 35
THE FOREST FOR THE TREES Nature has been refining the structure of ecosystems through trial and error over millions of years and competition between species, natural selection and adaptation have moulded the species in each to fit together like a jigsaw puzzle. It would be an ambitious project to design an ecosystem made up of complex patterns and processes, with a selection of species which had not evolved together. When we plant a garden, we might re– contour the ground, build up the soil, put in irrigation and plan where each plant will go, its texture and colour, height and density. Then we will plan the maintenance; fertiliser, irrigation again, weeding, plant replacement, frost control. Remember the story about the taxidermy pheasant? When we are thinking about ecological restoration, we are thinking about restoring the processes which manage a natural area and avoiding the ongoing maintenance that a garden needs. At the same time, we are thinking about the patterns we find in natural areas. These might be the structure of a forest, tall trees, understorey shrubs, epiphytes, climbers and scramblers, ground covers and ferns. Other patterns to consider are the natural distribution of species across the landscape: where species are found and where they are not found. As a society we have changed the landscape enormously; now we are altering the natural distribution of genes, species and ecosystems, with little understanding of the long–term consequences. Now is the time to limit those changes as much as practicable by following nature’s patterns as closely as possible. But as much as we may want to restore a natural landscape, there will always be limitations. We may, for instance, want to avoid shading of our houses or preserve the views of rivers, lakes and distant hills. Power lines, stopbanks and roadways also take priority. It may be necessary to limit the height a forest can grow to but if we do, the consequence will
always be the need to control weeds that will take advantage of the situation. As a general rule, a planting project will only suppress weeds that cannot grow as tall as the planting and taller weeds will always find a way to come through. I have had more experience of that rule than I care to recount, like when I planted carex sedges in a damp area: they make a dense sward, but pampas (Cortaderia jubata and C. selloana) keeps growing through it. I planted low–growing flaxes on the riverbank to preserve the view, but wattles grew right over them. The objectives for a project might have a big influence on the selection of a site. There will be times when we have a particular site in mind and want to re–establish native forest there. There may be other times when there are particular objectives. These might be restoring examples of a forest type, improving water quality, removing sources of weeds, providing wildlife habitat or re–establishing the continuity in a population. You might have the option of choosing from a number of sites without the resources to restore all of them. In this case, selecting either the healthiest forest remnants, greatest sources of water contaminants, weediest sites, ideal wildlife habitat or optimum location to improve natural dispersal will help achieve particular objectives. Whatever the objectives of the project, it makes sense to closely follow natural patterns, restore what would naturally grow there and avoid further disruption of the natural world. In the previous section, possible objectives for a restoration project were explored. Setting out what a project aims to achieve is useful when promoting the project to supporters, selecting a specific strategy and reviewing the success of the project. This must always be the first step in any plan. Site assessment Walk over a site with a note pad and camera and record both the weed and native species present and describe the variety of landforms. 36
THE FOREST FOR THE TREES Many sites are better divided up into smaller sections with similar landforms or vegetation so each section can be treated appropriately. I like to photograph each section so I have a reminder of what it was like before anything was done. I try to find a view which is typical of the site and clearly shows the landform and current state of the vegetation. In assessing a site, first describe the physical characteristics. Is it flat or sloping and how steep? What is the soil like and how does it vary across the site? Describe the wet and dry areas. Is it prone to flooding? How high might the floods be and how long are they likely to last? Estimate and ask about wind and frost in the area. If there is already some woody vegetation there, it can provide useful information about the levels of flood, wind and frost that can be expected. The presence or absence of sensitive species can give a clue to the physical conditions found on a site, but remember that many young plants can be more sensitive than older trees, and frost can be much more severe at ground level than in the canopy of tall trees. Some of these trees may have established at an earlier time, when there was more shelter around. New seedlings of the same species may need similar shelter to survive. Record all of the native species already on the site. These are more valuable than any that can be planted, for two reasons. They may be remnants of the original vegetation and may have some characteristics unique to the district. These specimens are likely to have native epiphytes, associated mycorrhizae and parasites, which would be difficult to restore any other way. Protecting them will preserve associated processes and may save something unique. The second reason is that established trees and shrubs provide more shelter and shade than small seedlings, so they advance the succession of species on the site, providing shelter and shading out lightâ€“demanding weeds. This allows the establishment of species which would otherwise need to be planted later.
These remnants are also a clue to the natural vegetation of the site. Their presence in small amounts may be an indication of what to plant. If they are already present in large amounts, they might be expected to spread naturally, so it may be unnecessary to plant them. I find it really helpful to look at neighbouring areas of native vegetation, if they exist. These are a useful guide to what grows naturally in the area and may be a good seed source for propagation of native plants for the project. Nearby vegetation also has the potential to spread into the project area, contributing significantly to the range of species to establish on the new site. The third aspect to consider is the range of weeds already on the site and those likely to invade if the project progresses. Sites which have been grazed up until the time of planting may be easiest to prepare. Pasture grasses cover the ground and inhibit the establishment of taller weeds. Left ungrazed, these grasses will grow and shade the new plantings, but can easily be pressed aside once or twice during the growing season to release the young seedlings. They can also be sprayed with grassâ€“ selective herbicide if the planted species are not grasses. Care should always be taken to ensure equipment is scrupulously cleaned before relying on a selective herbicide and unnecessary contact with desirable plants must be avoided. A grazed area may not have significant weeds on it, but as soon as a fence is erected and stock is excluded, weeds can begin to appear. Exclusion of weeds is an important aspect of any planting plan, so an indication of the weeds which are likely to establish is a necessary part of the site assessment. One of the main functions of the native plants we plant is to outâ€“compete weeds where possible. To achieve this, we need to create a plant community taller than the expected weeds and shadier than they can tolerate, if possible. 37
THE FOREST FOR THE TREES Developing a strategy Once the site has been described and the objectives identified, a strategy can be contemplated. The amount of detail in a restoration plan will depend on who will be implementing and who will be supervising each aspect of it and how much guidance they need.
Establishing such a community will take time. Until it does, the project will be vulnerable to weed incursions. Planting projects which are not well managed or not designed to eventually establish a self– sustaining community, risk simply providing a new site for weeds. Areas like riparian margins which have been unmanaged for some time are likely to have a range of weeds. This will require a carefully–considered weed management plan, so identification of the exotic weeds and an indication of how prevalent they are, is important. If, for instance, we expect grey willows may reinvade the site, we are pre–warned to plant a forest too tall and dark for willows to grow there. If we do this, the need to control all of the willow seedlings appearing diminishes, because we have confidence the planting will eventually eliminate any willow seedlings and dominate the site. And there are other threats to restoration planting projects. Not all sites are vulnerable to grazing livestock, but some are. It is useful to know before starting the project what threats there might be from pukeko, rabbits, hares, possums, goats, sheep, deer and cattle, so that protection can be included in a plan. There are products which protect plants from hares and rabbits and good fences keep out farmed animals, but it is not so easy to prevent floods and droughts. New Zealand has 72 naturally uncommon ecosystems described in Williams et al. (2007). Many of these meet the International Union for the Conservation of Nature (IUCN) Red List of Ecosystems criteria for threatened ecosystems. Any site which may meet these criteria— naturally uncommon landforms, sites modified by geothermal activity or by natural animal activities—should be treated carefully by, or by following the advice of, suitably qualified people. If the intended site appears likely to fit this description, the Department of Conservation should be consulted.
Weed–control strategy Having identified any weed issues, plan the control of existing and expected weeds: this will not be a one–off event. Clearing native forest to create pasture took generations to perfect. Dealing with a complex matrix of weeds and reversing the process to recreate native forest will take at least as long to master. The first step is to create a blank canvas to work on, in which young seedlings have a chance to establish before they have to compete with weeds. Some weeds will in time be out–competed by a community of native plants; others will persist and continue to pose a threat, so it is helpful to explore some of the tools available. A combination of approaches will inevitably be necessary on each site. A useful plan will outline not only the weeds to be controlled, but appropriate methods and the time frame involved. Manual or mechanical control For smaller projects and some specific weeds, this can be the best approach, or at least a useful addition to an arsenal. Avoiding the use of herbicides might save valuable native plant seedlings found naturally on the site and might be necessary on a project which is close to organically grown crops. Wandering Jew (Tradescantia fluminensis) can be rolled up and left in piles, to be covered with black plastic until it rots. Some of the annual weeds like wild turnip, beggars’ ticks (Bidens frondosa) and inkweed (Phytolacca octandra), which appear after the area has been cleared and planted, may be best hand pulled. 38
THE FOREST FOR THE TREES This will avoid herbicide damage to adjacent newly planted plants. Climbers like jasmine (Jasminum polyanthum) or Japanese honeysuckle (Lonicera japonica) are often best controlled by cutting them off at ground level and again at eye level, ensuring all stems are cut. Regrowth from the ground can then be easily sprayed with appropriate herbicide. Vines left in the trees will in time die back, allowing new growth from the host tree to emerge over the old vines. Knapsack sprayer Herbicides are poisons and should be treated with care, but are useful tools. Appropriate use of herbicides can really help reduce the amount of work required to clear weeds and avoids the need to disturb the soil. Knapsack sprayers are designed to be carried on the operator’s back and carry five, 10 or 15l of mixed herbicide, possibly marker dye, wetting agent and water. This allows access to anywhere a person can walk or possibly climb. I find an adjustable jet is useful; a narrow jet can be propelled several metres to the target weed and a wide cone can be misted over a close specimen. Spraying a weed plant can be likened to spray painting a car or piece of furniture. The aim is to cover the object completely, without having overspray running on to the ground. Marker dye is useful to check this is done well. Because the poison solution is carried on the back, the amount used at any one time is limited. A knapsack sprayer is useful for small or very inaccessible sites. A knapsack can also be useful on a larger project, where a selective herbicide is needed for a specific task, like glyphosate on pampas or metsulfuron–methyl on lilies or irises. For larger areas though, more serious equipment is helpful.
The knapsack sprayer is good for inaccessible places and careful control of spray material.
Motorised sprayer mounted on a vehicle can apply a significant amount of material in a short time.
per minute, to larger petrol or tractor–driven pumps capable of 50l or more per minute, supplied from a tank of 200, 400 or 800l. Sprayers like these deliver the herbicide through a hose to a handgun. The hose has to be dragged to the site, but much less frequent mixing of herbicide is required and it has the Motorised sprayer capacity to cover larger areas quickly. The These range from small, electrically– increased pressure and volume delivered by operated spot sprayers capable of a few litres this equipment allows the herbicide mixture 39
THE FOREST FOR THE TREES Mowing, slashing and mulching Spraying herbicide may control the plants or parts of plants that are exposed and easy to get to, but for dense concentrations of vine stems like blackberry (Rubus fruticosus agg.) or jasmine (Jasminum polyanthum), mowing or slashing may be necessary to remove the Drilling and injecting dead material and expose live stems beneath. While other methods of applying herbicide Sometimes one weed species may be can result in spray drift and collateral damage, covering another below it. Take blackberry drilling a series of holes into the trunk of (Rubus fruticosus agg.), which may have trees and injecting a concentrated herbicide wandering Jew (Tradescantia fluminensis) mixture can direct the herbicide exactly beneath it. In this case, a programme focused where it is needed without waste or collateral on spraying the blackberry might need to be damage. followed by mowing with a scrub cutter or Holes should be angled down to prevent tractor–mounted rotary slasher, then finally spillage and angled to either side rather than repeat applications to the wandering Jew. straight in, to keep the herbicide close to the phloem–conductive tissue just under the Aerial spraying bark. For large areas, aerial application might be This is a relatively simple procedure when the most cost effective approach, but it is also trees have a single upright trunk, but becomes the most widely dispersive one. Great care more difficult with species like grey willow must be taken to avoiding application over (Salix cinerea) that might have multiple or water or damage to desirable plants growing horizontal trunks, sometimes sprouting roots under a canopy. from several places. Helicopter spraying can be useful on very A good guide to this method can be found steep, otherwise inaccessible sites, though. at http://www.waitakere.govt.nz/cnlser/ Willows can be sprayed in this way, but the pw/greennetwk/pdf/willow–control–best– economy of this approach should be weighed practice.pdf against the threat to swamp coprosma/ hukihuki (Coprosma tenuicaulis) or sedges Cutting and stump pasting growing underneath. Climbers and smaller trees can be cut near the Although more time consuming, a handgun base and the cuts treated with concentrated operated from a helicopter may be more glyphosate paste or “vigilant” paste containing accurately directed than a spray boom. picloram herbicide. Treating both sides of Aerial spraying using drones is an emerging the cut is important to avoid regrowth of the option which deserves to be explored. upper portion. Avoid dropping picloram on A systematic approach to spraying the ground at all costs because it is persistent I was once offered a contract which specified and mobile in the ground, so can kill desirable all weeds were to be killed, but there was to species as well. be no damage to native species. If only it were Cutting down may not be such a good that simple. idea for larger trees, especially where they In that situation, I was looking at several dominate a site, because too many felled hectares of wetland covered with tall trees may make the site inaccessible and the blackberry (Rubus fruticosus agg.) and swamp standing dead trees may provide valuable coprosma/hukihuki (Coprosma tenuicaulis) shelter for the newly planted seedlings. underneath. to be forced between leaves to less accessible parts of the weed plants. These typically use more herbicide, which is not so carefully targeted but cover more ground and is more effective for larger or more widespread weeds.
THE FOREST FOR THE TREES The only way to successfully achieve the goals of that contract would be to painstakingly hand weed all of the blackberry and remove it from the site; clearly impractical on such a large scale. All ecological restoration projects involve compromise in order to make the very most of resources available. And with all weed spraying, there is a compromise between effectively eradicating a serious weed and avoiding damage to native plants. Where a native species is common and a weed is scarce, it may be important to completely eradicate the weed and accept some collateral damage to the native plants. But where a native species is locally scarce, it may be more important to protect the native plants at all costs and accept some survival of weeds. Perhaps in cases like this it may be useful to take and propagate cuttings of the native plants for reintroduction to preserve the local genetics. On some sites the situation may vary from one square metre to another and the approach modified accordingly. This requires not only good ability to identify the native plants and the weeds, but also a good knowledge of their growth habits and the likely outcome from competition between them. This also means that weed spraying on restoration projects requires sustained concentration and careful judgment. It is important to cover the whole site and to avoid covering the same ground twice. Think of it like spray painting a car: Each part must be covered, but only once per application. For this purpose, it helps to mentally divide the site to be sprayed into discrete sections and to complete one section before going on to the next. On a simple, homogeneous site this may mean strips which can be easily covered with a single pass of the sprayer. On more complex sites, this may be a combination of strips, modified to completely cover similar landform and vegetation and delay covering ground of a different character until the first section is completed.
Many weed species require coverage over a high percentage of their surface to get a good kill. This will mean not only starting at one point and applying the herbicide evenly over the surface until the whole plant is covered, but moving around the weed to ensure that it is covered from all angles. In the case of vines like honeysuckle or jasmine (Jasminum polyanthum), it may be helpful to cut the stems close to the base, particularly if they are growing over desirable plants. The regrowth on the ground can then be sprayed the next time the area is treated. Often weed plants grow among desirable natives we want to protect and it is seldom practical to spray the weed without significant collateral damage. The best approach is to separate the plants, sometimes pushing the weed over with a boot then spraying close to the ground where overspray can do no harm. With plants like cabbage trees/ti kouka (Cordyline australis), flaxes and others with spreading foliage, I find it helpful to separate out the foliage, then lean my back against the plant to protect it from overspray as I deal to the weed. In the case of restoration projects, what we donâ€™t kill may be as important as what we do. Selective herbicides can be particularly useful. Grazon and other herbicides containing only triclopyr will not kill most grasses, sedges or rushes. This can be very useful when planting sedges en masse. Leaving grasses, while controlling woody and broadleaf weeds, can also be very useful because the grasses will provide a low cover and help suppress germinating, taller weeds. Herbicide containing haloxyfopâ€“P, for example Gallant will control grasses without damage to certain other groups of plants. These selective herbicides are only useful if equipment is scrupulously rinsed before and after use. Reserving equipment for the exclusive use of one particular herbicide may be justified. 41
THE FOREST FOR THE TREES Protection from animals The native plants of New Zealand evolved in the absence of browsing mammals and may not be resilient to them. Fencing out sheep and cattle and keeping them out is really important. Permanent fences are best, but electrifying at least some of the wires is even better. A temporary electric fence, which can be quickly reinstated, can be the best alternative in flood–prone areas. Existing grazing, however, may help to maintain a population of native plants, perhaps because they are adapted to disturbance or perhaps because grazing is controlling some weeds, so this should be well understood before fencing. Possums, rabbits and hares can be a problem in some areas and a range of products is available to repel these pests or to shield plants from them, but can be expensive, so consider the cost carefully. Sometimes it is necessary to employ a contractor or local enthusiast to hunt the hares on the surrounding farmland to give the plants a chance until they are tall enough to discourage hare browsing.
In the restoration of natural areas, diversity within the species is a distinct advantage. Having a range of individuals within a species, with variation of life strategies—fruiting times, colour, seed size, rate of growth and durability—allows a species to occupy a greater range of habitats. Greater diversity also helps species resist diseases, more densely populate a locality and adapt to environmental changes much more effectively than a population of genetically identical individuals might do. When sourcing or propagating plants, the size at planting time is an important consideration. Smaller plants cost less to grow and take less time to produce than larger specimens. I have done some trials with varying sizes of plants at the time of planting out, but there is still much to learn. Quick–growing species like manuka (Leptospermum scoparium) or koromiko (Veronica stricta.) may be satisfactorily established from smaller specimens while slower–growing trees like tawa (Beilschmiedia tawa) or pokaka (Elaeocarpus hookerianus) may benefit from being a larger size when planted out. A weedy site may benefit from larger specimens, better equipped to out–compete weeds. A dry or drought–prone site may favour smaller specimens better equipped to establish sufficient roots before the next drought event. Most plants for restoration purposes are grown in plastic bags and pots of about 1l to 1.5l, while larger trees might be in four to five– litre pots. The quality of plants is also important. Plants should be mature enough for the root ball to fill the container and anchor the plant securely, but not so old that the root ball is moulded to the shape of the container or has exhausted all of the nutrients in the growing medium. Plants should have been grown in a sunny outdoor position similar to their intended planting site, with plenty of space between the plants so that side branches are not discouraged. Plants grown like this tend to be bushier, have smaller, tougher leaves and a
Propagation and sourcing of plants Plants for ecological restoration are generally propagated from seed. This is to ensure every seedling is genetically unique. At some seed collection sites, though, lone specimens may be the only source of seed. If this is the case, cuttings or other clones may be preferable to avoid using plants that are the result of self– pollination, which can result in inbreeding. It may be important to produce identical plants in a horticultural situation. This can be achieved by growing first–generation hybrids, as in cereal crops, or by some form of vegetative propagation. Roses are propagated by budding, fruit trees by grafting, orchids by cloning and many other garden plants by cuttings. These offspring are all genetically identical and their uniformity desirable in a horticultural setting. 42
THE FOREST FOR THE TREES shorter span between the nodes where leaves and branches originate. The diameter of the trunk is a better indication of the size of a specimen than the height. Ecosourcing has already been discussed. Plants in the nursery should be kept separate from others of the same species from a different location and the provenance clearly labeled.
then ground cover. In natural areas, after disturbance, young tree seedlings might grow very close together, depriving the smallest of light so it fails to thrive and eventually dies. This process over time leads to wider, although not necessarily even, spacing between trees. It is helpful to anticipate the effect of this competition and evenly distribute canopy trees over the site, allowing each space to grow without competition from other trees. This is the best chance for each tree to grow to maturity and contribute to the canopy. Avoiding competition at this stage ensures the most efficient use of the trees available but requires careful site selection to ensure each species is planted in the most appropriate spot. Evenly spacing out the canopy trees also avoids having areas devoid of the quickerâ€“ growing colonising species which are important for closing a canopy as soon as possible. This function would otherwise be performed by natural competition between individual trees. Identify which tree species require some shelter, which require strong sunlight, which tolerate wet soil and which tolerate wind and frost. Locate each species accordingly. Referring back to a reference ecosystem is the key to achieving this. It may be wise to revisit some natural areas, measure the distance between trees and observe the environmental conditions of the various species prior to planting out. Many trees are slower growing than shrubs or have less dense foliage in their juvenile form. Planting only canopy trees on a site will make the project slow to establish and vulnerable to weeds, so usually other types of plants are necessary as well. Understorey species can be particular about their environment, so they are the next to space out. Depending on how exposed the site is, only some of the understorey species will thrive in open areas in the early stages of the project.
Planting day Plant placement Most projects space seedlings between 1m and 2m apart, depending on the weediness of the site and the ability to manage future weeds there. Existing trees and shrubs, whether exotic or native, can significantly reduce the density of planting as they provide shelter and shade out other weeds. I find it useful, once all of the plants have arrived, to walk over the site and note the variation in conditions found there. On natural landforms there is likely to be some variation in soil moisture, slope, soil type, shelter, sunlight, frost and wind exposure. No matter how detailed the planting plan might be, this is a good time to finalise where each species might be concentrated and where it should be avoided. This is a good time to pace out sections of the site and allocate appropriate numbers of each species accordingly. I find fence posts, if evenly spaced, to be a useful guide to ensure that plant density is relatively uniform over the whole site. Following a grid pattern also helps with this, while ensuring the gaps close over at the same time. A uniform grid also facilitates release spraying of the ground between the plants because it makes it easier to predict where the next plant will be found. For simplicity, it is convenient to group the plants into the five categories, or possibly the first three, mentioned earlier, that is, the trees, understorey and colonisers, followed by climbers, scramblers, lianas and epiphytes, 43
THE FOREST FOR THE TREES If these can be introduced early, they will have the opportunity to take advantage of high light levels and start producing seeds so that once a canopy of trees is established, they are well placed to regenerate, spread out and form a complete understorey. Once a canopy is established, conditions will be more stable for understorey species, which will be less threatened by the environment, but wonâ€™t grow as quickly or produce as much seed because of the increased shade. On any site there will be minor variations which suit different species. If there are existing exotic trees on the site, like willow (Salix spp.) or hawthorn (Crataegus monogyna), or natives like mahoe (Melicytus ramiflorus) or kahikatea (Dacrycarpus dacrydioides), these will provide very good protection from frost for understorey shrubs, which might otherwise need to wait until later in the project. In wet sites there can be areas of slightly higher ground and in dry areas, shallow depressions which provide slightly better habitat. It is a good idea to seek out all of these opportunities for sensitive species. Topography can be a guide to the soil conditions below, but can sometimes be misleading. The bottom of a slope is often quite damp and the crest of a hill quite dry. But this isnâ€™t always the case; sometimes ground water comes to the surface in the middle of a slope. The existing vegetation, both the species composition and the condition of the plants, whether it is pasture grasses, woody weeds or native scrub, can be a useful clue to the soil conditions and the right species to plant there. Sometimes it is useful to dig the holes for trees and shrubs and have a look at the soil before making the final decision about where each species should go. On planting day, colonisers will be the last plants to be placed on the site. They fill in the gaps between the other species and ensure that a closed canopy establishes in a timely fashion. These species provide shelter from wind and frost as well as helping to suppress
weeds, but are the first to fail as the others grow and fill in the gaps. Karamu (Coprosma robusta), manuka (Leptospermum scoparium), kanuka (Kunzea spp.), cabbage tree/ti kouka (Cordyline australis), and flaxes (Phormium spp.) are all very useful for quickly establishing shelter and shading out weeds. If the area is retired pasture with only short grasses and pasture herbs, this group might comprise 60% to 70% of the new planting, particularly in exposed conditions. If there is some cover, the total number of new plants for a given area will be less and the reduction will be mostly from these colonising plants because the existing cover will perform a similar function. These plants should be evenly spaced between the plants of other groups, completing a more or less uniform coverage of the ground. Consideration might be given to providing shelter from wind and frost for the other groups of plants if required. Flaxes quickly grow to their maximum height of between 3m and 4m, but are particularly intolerant of shade. They can be quite useful for providing instant shelter around the edges of a project and will attract birds to their nectar bearing flowers. But they donâ€™t contribute well to a canopy, so apart from their natural habitat in wetlands or on coastal cliffs, they only make a limited contribution to establishing a forest community. Putting the plant in the ground Plants should be established in the ground to the same level that they are in their pots. Once the pot or bag is removed, a hole must be dug to the appropriate depth. Plants that have been contained in pots or bags for a long time may have roots that encircle the root ball. These may continue to enlarge after the plant is established in the ground, eventually causing a constriction or a weak point in the roots. 44
THE FOREST FOR THE TREES To avoid this, loosen the root ball and tease out the offending roots or alternatively, make a vertical cut down the root ball to encourage new roots to grow outwards into the new soil. This is particularly important for long–lived and tall tree species and not so important for herbaceous species like flaxes and sedges. Species have varying tolerance of root disturbance. Manuka (Leptospermum scoparium) and kanuka (Kunzea spp.) are very sensitive and should be treated with care. Plant roots have a remarkable ability to grow through hard soil, so it is unnecessary to loosen the ground around the plant. It is necessary, though, to make sure that, once the plant is placed in the hole, it is in good contact with the soil and is firmly anchored there. Since most planting is done during winter when the soil is wet and soft, pressing down firmly on the ground surrounding the plant once it is in its hole and the gaps filled in, should be sufficient. In very wet ground, the plant can often be placed in a hole of the right size, then the surrounding ground pressed down to squeeze the soil around the plant. A cane stake or bright tape is sometimes used to mark each plant to help with later maintenance. Plants should in most cases stand up on their own, without being tied to a stake. If a stake is considered necessary, the plant should be tied with natural tape or a flax or cabbage– tree leaf so that after a year or so, the tie will break down naturally. Tape to make plants more visible should be tied to branches, not to the main stem, in case the tape constricts it. Fertiliser, although commonly used in amenity situations, is not normally recommended. Planting is often done to help reduce nutrients in waterways, so adding fertiliser to the soil may not be a good idea. While providing necessary nutrients, this can reduce water uptake at the time when it is most needed; directly after planting.
Selecting species adapted for the unmodified site is preferable. Timing Plants in the nursery are sheltered from wind and frost and regularly watered. When they are planted out, they have to acclimatise to the new conditions and grow roots into the new soil to support new growth. Winter, then, is generally a good time to plant out because the existing roots can easily provide sufficient water during cold, wet conditions. This gives plants time to grow new roots before the weather gets warm and dry and their demand for water increases. With well–established roots, the plant is then able to put on new growth and compete well with weeds by the time spring comes. Small plant specimens which are sensitive to frost, however, could be seriously damaged if they are planted at this time of the year and are best left to early spring. This is because in the nursery they may not have been exposed to sufficient cold to induce the growth of hardened tissues which tolerate frost. Small plants also have their growing tips closer to the ground where frost is more intense than even a few centimetres higher up. Frost might destroy a significant portion of a very small plant, but after a season’s growth before the first frosts are encountered, the plant is better equipped to cope with a small amount of frost damage. Although flooding can occur at any time of the year, it is most common in July, August and September. Small streams with small catchment areas can increase in flow dramatically for short periods after rain, scouring the banks, washing out plants and depositing debris over a newly planted area. Larger rivers like the Waikato, with large catchment areas, can flood for several months at a time, completely submerging young native seedlings along the banks. The best time to plant in these cases is during the spring, after seasonal frosts and flooding has ended. 45
THE FOREST FOR THE TREES Maintenance and supplementary planting While the plan has been to establish a plant community which will compete effectively with exotic weeds, the project will still be especially vulnerable for some time. In order to protect the newly planted native seedlings and allow them space to grow, it may be important to hand pull weeds like inkweed (Phytolacca octandra), wild turnip (Brassica rapa sub sp.sylvestris) and black nightshade (Solanum nigrum).They grow much quicker than our shrubs and trees and if not controlled, can shade out natives and slow down their growth. Bindweed (Calystegia spp.), climbing dock (Rumex sagittatus) and climbing asparagus (Asparagus scandens) can spread to the site and seriously affect our planting. Honeysuckle, woolly nightshade (Solanum mauritianum) and jasmine (Jasminum polyanthum) may be the next to establish and with no protection, alders, elder, willows, walnut and wattle will eventually take over. Once we have a tall native canopy with a dense understorey, weeds will struggle but until that happens, regular monitoring and a control programme will be necessary to protect the investment in plants and time. There will always be a few casualties. Individual gaps are likely to be filled in time by the surrounding quick–growing plants, but larger gaps may need to be filled with replacement plants. In particular, the arrangement of canopy trees should be inspected carefully to ensure that they too will establish a closed canopy in due course. By this time, there will be more shelter on the site and more shade as well. This is a great opportunity to introduce tree and understorey species which would not tolerate the earlier exposed conditions found there when the initial planting work was done. After ten years, many of the colonisers will be failing to thrive, either because they are getting old or because they are being shaded out by longer–lived but slower–growing
species. At this time the canopy trees will begin to emerge above the understorey species, but it may be another decade before they close over the understorey. The story doesn’t end there. Seedlings of some of the trees, like kahikatea (Dacrycarpus dacrydioides), won’t grow up under a canopy because it is too shady, so over time trees like tawa (Beilschmiedia tawa), titoki (Alectryon excelsus subsp. excelsus) and pukatea (Laurelia novae–zelandiae) will establish, but kahikatea will be represented only by older trees standing proud of the canopy unless wind, fire or flood provide the young seedlings with a new opportunity. So far I have discussed the initial planting. Sometimes when I have led a field trip with school students to a forest remnant, I have offered a reward for anyone able to find a tree with nothing else growing on it. I have never had to pay up. Part of the richness of our native bush is found in the great range of species which perch up in or climb over trees and shrubs or embellish the forest floor. A planting plan must give guidance on introduction of new species into the project. Once a canopy is established, it may not be necessary to plant large numbers of plants, just sufficient to establish a breeding population of those species not likely to naturally disperse into the area, then allow them to set seed, disperse and compete with established species. Every site is unique, but it is extremely unlikely that no weeds will establish on the site as the plants grow. Once a tall canopy, dense understorey and healthy ground cover is established, weeds will have trouble competing but until then, they may be a threat and need controlling. Each weed species will pose a different threat and it will be important to clearly understand what threat that weed might pose, how competition within the site will progress and so what kind of control will be required. The section on specific examples of projects will give some ideas of how to approach this. 46
THE FOREST FOR THE TREES A timeline Clearing weeds, sourcing and propagating plants, establishing seedlings in situ, maintaining the site until it is self–sustaining and supplementary planting all take time. Scheduling events so each component or aspect of the project is ready at the optimum time requires timing to be considered, recorded and conveyed to those involved. A timeline will be a really important component of the plan.
species will be important to note: some will grow much faster than others. Survival of frost, wind, flooding and waterlogging will be important as well. The objective of monitoring is to assess the state of the site and compare it with the anticipated trajectory. If a project includes trials of plant species, size or spacing or weed control strategies, then the monitoring should help record and interpret the results of such trials. You can then modify your strategy on this and future projects in the light of this assessment. Forest monitoring on large areas requires sampling of a representative portion of the site. Because plant community restoration projects involve intensive management, they generally cover relatively small areas. The intensive management required for weed control provides an excellent opportunity to examine every square metre of the project site in detail, and to report on the growth or natural regeneration of new or existing plants, the growth of weeds, new weed and native species appearing anywhere on the site, as well as any new threats to the site. Illustrating these reports with photographs is good, particularly if they are taken of the same view over a period of time, so comparisons can be made. Restoration of plant communities may be part of a wider restoration programme, with wider objectives like providing habitat for native animals or improving water quality. If this is the case, monitoring for these objectives may well accompany that of vegetation.
Trials, recording and monitoring: Celebrating success and learning from surprises. The process of protecting what we have left and restoring natural areas is a complex one that we are just beginning to understand. For every project, there will be opportunities to try a range of approaches and watch to see what works best. People from organisations funding restoration projects expect to hear that work is progressing in a successful way. Taking photos of the site before the project starts, then recording the progress photographically is a good start. Recording what has been done and when is also helpful to funders. Typically, we all want to put a positive spin on any report, especially to anyone funding the project, but in reality, it is when things don’t go according to plan, when they don’t work well, that the best learning opportunities are found. Make sure these instances are recorded in your progress report, and that the lessons learned are passed on. Always keep a record of the plan for weed control and for planting, note any changes made to the plan. When the work is done and as the plants mature, this can be a useful reference to see what has survived well and what hasn’t. Start by monitoring the survival of the newly planted plants and the return of any weeds. As time goes by, the growth of different
Summary A plan systematically outlines what we hope to achieve, what the site is like prior to starting the project, what activities like weed control and planting will be undertaken and how success will be measured. Every project starts with a unique site and has its own array of resources and specific 47
THE FOREST FOR THE TREES objectives. The following section explores a number of projects and the solutions chosen for each. Although all of the examples are from the Waikato region, the principles applied are universal.
THE FOREST FOR THE TREES
Examples of restoration projects One size does not fit all
honeysuckle (Lonicera japonica), gorse (Ulex europaeus), blackberry (Rubus fruticosus agg.) and royal fern (Osmunda regalis). In the interests of sustainability, then, this taller, richer swamp forest it is adopted as the long– term objective and a unique concession to the limited resources available is employed. The third example, Timelines, continuums and gradients, is chosen to illustrate the use of reference ecosystems. The Te Aroha Mountain site has adjoining mature and regenerating native forest to the north and the south as well as on higher slopes. There are examples of forest on the plains below, as well as some records of past vegetation on the site. The site for the project is unique, but exploring the trends along the gradients passing through the site and observation of succession there, is a valuable way to identify the character of the plant community to establish there. Without the use of this valuable information, the project would be a faint shadow of what it could be. Example four looks at a lakeside site. Past efforts have had limited success. Lessons have been learned from the team’s experience at this site and are applied in the revised approach. We learn so much when things go wrong, but restoration is such a new activity, that examples like this are rare and valuable. The fifth example at the Mangarata stream mouth describes a unique approach, working with the local community and describing the opportunities afforded when planting continues over many years. None of these case studies describes the
he following four examples have been chosen to illustrate a range of sites and a variety of approaches. Each of these examples outlines a pragmatic approach, making the most of available resources. None of these demonstrate the best possible practice, rather they show what can be done with real–life limitations. The first, the Waioteatua Stream, was chosen because it takes a site typical of the lower Waikato River, dominated by a limited range of exotic trees and climbers, to a much richer, native–dominated plant community. The presence of both native and exotic trees on the site allow for the planting of a much wider range of species than would be the case without their presence. This case study introduces an example of a management plan template which might be usefully applied to other projects. The second, Lake Maratoto, introduces a very large project with a very limited budget. This case study outlines a minimalist approach which still aims at instating a rich, diverse forest. The wetland surrounding the lake is very poorly drained and might be planted with only low–stature wetland species that we can be sure of thriving in the conditions. But there are indications on the site that a taller, richer plant community could potentially establish on the site. This taller, denser, richer plant community would have the potential to out–compete low–stature, light–demanding wetland plants. Without this described approach, the site would soon be invaded by grey willow (Salix cinerea), Japanese
THE FOREST FOR THE TREES complete reassembly of an ecosystem where none existed before. Time and cost constraints have ensured that only a few steps in the right direction will be achieved, but it is hoped that they are useful, cost–effective steps and they are in the right direction.
For most of the year, the river keeps within this channel, but for a few months in late winter and occasionally in summer, there is so much rain in the headwaters that it spills over the banks and floods the surrounding land. During these floods, the water carries silt washed into it by the rain. The flood waters Restoring the Waioteatua Stream Mouth slow as they spread out over the surrounding In its lower reaches, New Zealand’s longest land. As this happens, silt is deposited along river, the Waikato River, flows through a the banks, particularly where it first spills channel cut through pumice sediment which over, creating a levee and silt–laden wetlands it deposited itself in past millennia. beyond. The river carries not only silt from its banks, pastures, roads and earthworks in the catchment, but also the nutrients nitrogen and phosphorus, mainly from pastoral farms. Because the river flows through such productive farmland, alongside the country’s busiest roads and through a major city, there is little left of the unique, tall, productive, diverse forest which once clothed its banks. Introductions of new plants from around the world: willows from Europe, honeysuckle from Japan and wandering Jew (Tradescantia fluminensis) from Brazil, have replaced most The Waiteatua Stream site before weed control. of the native plants and made it difficult for
The Waiotuatea site from above. Note that low grass is retained along the road for safety.
THE FOREST FOR THE TREES them to re–establish. Seeds and vegetative material from these weeds are spread to new sites whenever the river floods. No intact remnants of native vegetation remain along the lower river margins, but there are small, highly modified fragments which give a clue to their character and may provide seed sources for their restoration. The Waioteatua Stream flows from the west, into the Waikato River between the towns of Ngaruawahia and Huntly. The unmanaged land surrounding the confluence has been selected for this restoration project. The project aims to re–establish a small fragment of authentic native forest on Waikato District Road Reserve immediately upstream of the confluence of the stream with the river. Planting native forest here is expected to achieve a number of results. • A small step towards eliminating a range of ground and tree weeds from the river bank. • Restore healthy populations of 25 native plant species from nearby natural sources so that they have an opportunity to recolonise ground cleared of weeds. • Provide a site for the regeneration of nearby native plants as insurance against their local loss. • Restore natural landscape amenity value to the site. • Provide habitat for native birds and encourage native birds to disperse native plant seed and pollen. • Provide an example of healthy plant community and restoration practice for other similar projects nearby. • Sequester carbon in the form of biomass to contribute to the offset of fossil fuel use and deforestation. An initial survey of the site revealed among the many weeds a surprising number of native plants. The following restoration plan describes the site, outlines objectives for the project, details a weed management plan and prescribes a planting programme to re– establish native forest.
Weeds under control after two summers.
Native planting competing with the weed growth five years on. It is hoped that this example may be a useful template for other projects you may be planning. The Waioteatua Stream Mouth Project 1. Site description 1.1 Location: The site covers the margin of 410m of the lower Waikato River on the true left bank 1.2 Boundaries: Part of the site is bounded by the Waikato River on one side and Road Reserve on the other. The southern end is bounded by the property of Waikato District Council and occupied by a local farmer under a grazing lease. 51
THE FOREST FOR THE TREES 1.6 Native vegetation: Existing: Cabbage tree/ti kouka (Cordyline australis), and mahoe (Melicytus ramiflorus) are common and the climbing ferns hound’s tongue (Microsorum pustulatum) and leather–leaf (Pyrrosia eleagnifolia) are abundant on trees. Of the native climbers, pohuehue (Muehlenbeckia australis) is common, with the occasional supplejack/kareo (Ripogonum scandens) and one example of kaihua (Parsonsia heterophylla). There is also a solitary kahikatea (Dacrycarpus dacrydioides) and kowhai (Sophora microphylla). Nearby natural areas of vegetation: As well as the mahoe (Melicytus ramiflorus), the nearby riverbank also has pigeonwood/porokaiwhiri (Hedycarya arborea) and kawakawa (Piper excelsum). The Hakarimata Scenic Reserve and Taupiri Mountain Reserve are within a kilometre of the site and both have a good range of lowland forest species, but lack specialist riparian species because both reserves are confined to higher ground. 1.7 Significant weeds.
The northwestern end is bounded by The Waioteatua Stream. 1.3 Topography: The site is flat to gently sloping. It contains land above the regular annual flood level and some land regularly flooded. On the road side there is a depression flowing north towards the Waioteatua Stream, which is damp in summer and regularly flooded in winter. 1.4 Hydrology: The size of the Waikato River catchment, the effects of deforestation and hydroelectric power development all affect the nature of the flow of water and characteristics of flooding along the river. A small tributary stream is likely to swell to many times the normal flow rate during a short rain event, but just as quickly as it rises, the flood will subside. Along the Waikato, high river levels can last for months, but seldom result in a raging torrent. Some of the riparian plants common along the tributary streams can be seen with flood debris high up in their foliage, but fail to survive flood inundation for the long periods experienced along the river. 1.5 Soil: The soil is a fine pumice alluvial silt. Weed Crack willow
Species Salix fragilis
Liqustrun sinense/ L.Iucidum
Pampas Japanese honeysuckle
Cortaderia Selloana/ C. jubata Lonicera japonica
Calystegia sepium/ C.silvatica
Yellow flag Iris
þ þ þ þ þ þ þ þ þ þ þ þ þ þ
THE FOREST FOR THE TREES 2. Site objectives 2.1 Biodiversity: Restoration of the site will preserve the remaining native plants and allow them to regenerate. Reintroduction of plant species, locally uncommon but characteristic of the area, like weeping kowhai (Sophora microphylla), turepo (Streblus heterophyllus), Coprosma rigida and rotundifolia, pigeonwood (Hedycarya arborea) and swamp mahoe (Melicytus micranthus) to this location contributes to overcoming fragmentation by helping them to spread along the riverbank. 2.2 Visual amenity: The site is visible from both SH1 and Hakarimata Road. It provides a backdrop to the view of the river from SH1. Re–establishing a native forest on this site aims to make the river more visually appealing from both roadways. 2.3 Bank stability: There is little curve in the river at this point and to some extent the bank is protected by a nearby island, so bank stability is not an issue. Increasing the vegetation cover at this site, however, is intended to help to precipitate sediment during flooding. 2.4 Weed control: The project aims to remove exotic weeds from this section of the river. This will contribute to a reduction in their ability to colonise riverbank particularly nearby Waikato RiverCare restoration sites. As weeds are progressively removed from the riverbank, restoration of new sites along the river will be easier and more durable. 2.5 Wildlife habitat: An important objective of the project is to enhance wildlife habitat. The native species introduced to the site are intended to provide year–round food for both native birds and introduced waterfowl. There is a significant area of wetland backswamp on this site, which will be enhanced by the reintroduction of fruit–bearing native species.
vegetation, so we need to look at several sites to gain the information needed to construct a reference ecosystem. Recording descriptions of sites referred to for the planning of a project helps explain how the plan was devised. Waipa Heights: At the end of Waipa Heights Road near Ngaruawahia, sandwiched between the steep hillside and the left bank of the Waipa River, is a neglected levee, a backswamp and footslope system. Although this area is occasionally grazed by cattle, it has the most complete assemblage of native plants to be found in this kind of habitat in the district. The backswamp is several metres above the summer river level, so it is only during extreme flood events that the area is flooded. Figure xxx shows a cross section through the area, illustrating the characteristic native plant species and where they are typically found. The site includes both species typical of disturbed areas, like karamu (Coprosma robusta) and cutty grass (Carex geminata), and species more typical of stable, long–established forest like turepo (Streblus heterophyllus) and swamp maire (Syzygium maire).
Karamu Bush: Almost encircled by a meander of the stream, Karamu Bush, near Te Pahu, has been isolated from the surrounding farmland for decades. The stream has easily cut down through pumice silt deposited by earlier incarnations of the Waikato River, leaving this “island” remnant well above all but the highest winter floods. The remnant flora is characteristic of well–drained ground, but tolerates winter flooding. Some of the trees and shrubs thriving here like manatu/ ribbonwood (Plagianthus regius) are now uncommon anywhere else in the area. 3. Constructing a virtual reference Wandering Jew (Tradescantia fluminensis) ecosystem covers the ground over the total area, although Despite being so small, our tiny restoration it is densest on the lower moister ground. In site has a range of natural habitats. None drier areas, particularly where people have of these exactly match any areas of natural worked to clear the wandering Jew in the past, 53
THE FOREST FOR THE TREES native shrub seedlings are growing higher species and where they are typically found. than the wandering Jew. Figure 1 shows a cross section through the Te Weranga Okupu Island area, illustrating the characteristic native plant The island lies within 25km of the Waikato species and where they are typically found River mouth, so daily tide movements dictate river level more than winter flooding does. No Mangahia stream: There is a permanent part of this 5ha island is more than 2m above wetland area where the Mangahia stream the highâ€“tide mark. Although consisting enters the Waipa River near Ngahinapouri. of wellâ€“drained silt soil, deposited by the Steep banks of pumice silt surround this river, wetland plants predominate. Its close wetland, so although old fences betray past proximity to the coast ensures the survival of attempts to graze the area, an interesting coastal species as well as those found further selection of native plants have survived up river. and today compete with blackberry (Rubus Figure 1 shows a cross section of the area, fruticosus agg.), wandering Jew (Tradescantia illustrating the characteristic native plant fluminensis), pampas (Cortaderia jubata and C. species and where these are typically found. selloana) and exotic sedges. Each of these sites gives us a small glimpse Each year, the Waipa River rises by as of the natural plant cover of our Waioteatua much as 6m for several months during the Stream site, but none gives the whole picture. winter, so that even quite tall shrubs and the Nowhere along the river is there an example lower branches of kahikatea (Dacrycarpus of vegetation on the low areas of willow, dacrydioides) are well covered with fine silt in which are dry most summers but under water the spring. all winter. Anything growing here must be well adapted Willows may have trapped silt in these areas to not only having occasionally waterlogged and changed the nature of the riverbank to roots, but having all of its foliage submerged create a habitat no native plants are adapted for months at a time. This, and other areas like to, or, alternatively, kahikatea (Dacrycarpus it, are a guide to the plant communities that dacrydioides) and shrubs may have once are best adapted to, and once occupied this grown here. Only by planting and watching habitat all along the river. carefully can we begin to explore the nature of Figure 1 shows a cross section through the a natural plant community on such a landform. area, illustrating the characteristic native plant The river has a significant effect on the
Figure 1: Exploring these reference ecosystems helps us to draw a picture of the primeval forest on this landform. 54
THE FOREST FOR THE TREES climate, moderating winter frosts, creating autumn fogs and maintaining humidity and moist soil through the summer. We have to learn what we can from each of the reference sites, but be careful with our inferences and prepared to learn from successes and challenges
stump may best control inkweed (Phytolacca octandra) if it grows too tall for other control methods. As the project matures, shade will eventually eliminate these weeds so they no longer pose a threat. Spray programme Preparation: Spraying should commence during summer of Years 1 and 2, using triclopyr for wandering Jew (Tradescantia fluminensis) and spot spraying yellow flag with metsulfuron–methyl and pampas (Cortaderia jubata and C. selloana) with glyphosate. Taking this approach should control other weeds as a matter of course. Thorough coverage of the area will be necessary during November in Year 2 to control any convolvulus (Calystegia sepium and C.silvatica) and this may require a repeat spraying later in the summer. Blackberry (Rubus fruticosus agg.) will be controlled by either the triclopyr or metsulfuron–methyl–based herbicides if applied during the summer growing season. Good control of the blackberry at an early stage will be essential to allow access to any wandering Jew (Tradescantia fluminensis) lurking beneath. Mowing, slashing or brush cutting may be necessary to knock down the dead canes and speed up the process. Wandering Jew (Tradescantia fluminensis) will regrow from a single stem node. Total control will only be achieved by repeated treatment, allowing time for dead material to rot down, then any viable nodes to shoot before repeating the application. Successive applications should require less spraying and any other weeds on the site are likely to be well controlled by this regime.
4. Weed management plan Planting is expected to be done in late winter or spring, after allowing two summers for weed control. Priorities for weed control are as follows: Preparation prior to planting: 1. Spray out blackberry (Rubus fruticosus agg.) and remove the canes to allow access to spray wandering Jew (Tradescantia fluminensis) underneath. 2. Thoroughly control wandering Jew (Tradescantia fluminensis) and significantly reduce convolvulus. 3. Remove privet and any other shrubs producing seed. 4. Remove lower branches from other trees and shrubs to allow access for weed control and planting. A detailed outline of the significance and suggested control measures for the weeds addressed on this site is included later in the text. Maintenance after planting Once the site has been cleared of weeds and planted, it will be vulnerable to invasion by a range of quick growing herbaceous weeds like inkweed (Phytolacca octandra), black nightshade (Solanum nigrum), and wild turnip (Brassica rapa sub sp.sylvestris). These and similar species are quick to invade a planting site and can shade out and sometimes push over newly planted native trees. These can generally be controlled with glyphosate, but because of the threat spraying poses to the newly planted natives, hand pulling may be preferable. Cutting with loppers and spraying the
Maintenance: Establishment of a canopy should in time control most weeds. The existing trees will help manage short–term herbaceous weeds. Wandering Jew, though, will not be controlled by the shade and convolvulus 55
THE FOREST FOR THE TREES 5.1 Planting plan The following plant list has been prepared. Each species has a unique strategy for capturing sunlight, accessing water and nutrients and regenerating and dispersing. Each species has a unique range of tolerances and vulnerabilities. Collectively they contribute to an efficient use of resources and to a resilient and selfâ€“ sustaining ecosystem. Strategies, tolerances and vulnerabilities of each of the species mentioned are discussed later in the book. Planting should be done on higher ground during winter but in September or October
may continue to be a problem for several years until the newly planted natives are well established. The site should be monitored for reâ€“ establishment of wandering Jew (Tradescantia fluminensis) and new growth of convolvulus in October and again in February or March. Any new growth should be spot sprayed with triclopyr. In subsequent years, the site should be monitored annually in spring and any weeds controlled as they appear. Great care will be required to minimise overspray or collateral damage to the newly established native plants. Species
Dacrycarpus dacrydioidies kahikatea
cabbage tree/ti kouka
Coprosma propinqua x
swamp coprosma/ hukihuki
THE FOREST FOR THE TREES on lower ground, after annual flooding has subsided. Space trees at between 4m and 5m spacings according to directions, avoiding the very wettest areas. Plant wetland species in wettest areas where wandering Jew (Tradescantia fluminensis) does not grow. Plant colonisers in open areas at 1.5m spacings and shade species in shadier areas at 2m spacings.
These utilise any light and nutrients not taken up by the initial planting, helping to make the site more resilient to weeds. Restoring all of these species to the riverbank ensures they are not lost from the district and that connection between populations is restored. Because the site already has a few native and many exotic established trees supplementary planting of climbers, epiphytes and ground covering species need not wait as long as on a bare site. The perching lilies kahakaha (Astelia hastata) and kowharawhara (Astelia solandri) can be grown in natural fibre bags and transferred onto the trunks of willows or alders. Climbing rata (Metrosideros spp) and parsonsia can be planted at the base of these trees as well. We may want to introduce ground ferns or alternatively choose to monitor the site and record the appearance of each species as it arrives. The number of plants is not so important for this phase, but it should be remembered that in order to establish a viable new population, offspring from at least 20 individuals is preferred and an eventual population size of over 50 is necessary. This, of course, depends on the possibility of exchange of seed and pollen from neighbouring populations.
5.2 Supplementary planting We would be optimistic if we expected every plant we put in the ground to survive. Planting well–grown plants, at the right time of year, in appropriate locations will give them a good chance, but there are bound to be some losses. Once other plants are established, the habitat has changed irreversibly. What might have been once an open, sunny position, might become shaded and more sheltered. This is an opportunity to introduce new species better adapted to the shelter and shade, which might not have been possible during the original planting. Shrub species not available at the time of planting can be introduced as they can be propagated, hangehange (Geniostoma ligustrifolium) being one of them. Epiphytes, climbers and ground plants can also be introduced to the site once other species are well established. Year 1
Planting Plant release Year 2
Plant release Jan
Site preparation Planting Plant release
THE FOREST FOR THE TREES 7. Predicted trajectory There are several weed issues on this site which will take time and ingenuity to overcome. Wandering Jew, because it tolerates such high levels of shade and because it will regrow from small stem fragments, is particularly concerning and planting will be delayed for two years until it is controlled. The jasmine (Jasminum polyanthum), growing under kikuyu grass (Pennisetum clandestinum) is expected to take three years to control. For this reason, planting in this area will be delayed for a further year. Planting will commence two years after weed control begins, starting on the higher ground in the early winter and progressing into the annually flooded areas as the winter river level recedes in the spring. The first release spray will occur in the spring. Despite there being significant canopy, bindweed (Calystegia spp.) and inkweed (Phytolacca octandra) will establish quickly and require control in the sunnier parts of the site. Wandering Jew (Tradescantia fluminensis) will continue to appear, both from remnant stem material and new pieces arriving in flood water. Karamu (Coprosma robusta) will be the most obvious shrub for the first few years because it grows so quickly. Although the ribbonwood/ manatu (Plagianthus regius) trees are smaller specimens than the other trees at the time of planting, they will quickly pass the others and be the most obvious ones for the first 10 years. By that time the karamu (Coprosma robusta) will begin to fail and as its soft wood decays and shade increases, other shrubs will spread out to fill in the gaps. Trees like kahikatea (Dacrycarpus dacrydioides) will still not be particularly obvious but after 15 years, they will stand out, being taller than shrubs like mahoe (Melicytus ramiflorus) or mapou (Myrsine australis). Small– leaved coprosma will begin to contribute to the mix at this stage, particularly in areas regularly flooded where other species are not so well adapted. Turepo (Streblus heterophyllus), pigeonwood (Hedycarya arborea) and
putaputaweta (Carpodetus serratus) are a bit slower to grow, so will be less obvious, but in 20 or 30 years’ time, their resilience and shade tolerance trumps the early establishment of quicker species. Once the wandering Jew (Tradescantia fluminensis) has been controlled on the ground, native shrub seeds will have the opportunity to establish. Mahoe (Melicytus ramiflorus) and karamu (Coprosma robusta) seedlings can be expected under the existing shrubs during the winter that planting is done. Seedlings of most other shrub species can be expected sometime within a decade, but it may take 15 or 20 years before tree seedlings begin to appear. This regeneration is necessary not just to replace trees and shrubs as they reach the end of their lifespan, but also to ensure the best adapted–species are established on every spot and so we do not rely on the guesswork in the planting plan. Regeneration will also drive ongoing revision of the species mix, with a gradual trend from early establishing species like karamu (Coprosma robusta), through intermediate species like mahoe (Melicytus ramiflorus) and towards more resilient species like turepo (Streblus heterophyllus) or pigeonwood (Hedycarya arborea) 8. Monitoring and reporting Determine trials: What do we want to find out? How will the regular river flooding affect species establishment? What species will tolerate the conditions close to the river? • • • • •
Points to include in maintenance reports: Patterns of species survival New weeds appearing/reappearance of weeds New native species appearing. Growth of plants (measure trunk diameter/height)
THE FOREST FOR THE TREES 1. Site description Lake Maratoto 1.1 Location: The site covers 14000 m2 Lake Maratoto is a peat lake formed by the growth of a peat dome interrupting the on the southern and eastern shore of Lake drainage from low hills just south of Hamilton. Maratoto, 3.5 km north of Ohaupo township.
The Maratoto project, drained lake bed. 1.2 Boundaries: Part of the site is bounded by a previous planting adjacent to the lake, part by the southern shore of the lake and the remainder by the low hills surrounding to the south and east. 1.3 Topography/Slope: The site is drained lake bed, with the level surface of the soil close to the lake level during winter. 1.4 Hydrology: With the soil level close to the lake water level during winter, the ground is waterlogged in winter, but the peat soil can be very dry during summer. 1.5 Soil: Peat 1.6 Native vegetation Existing: The site has been occasionally grazed and aerial sprayed to control weeds. Many of the existing native tree ferns have died as a result. Manuka (Leptospermum scoparium)
This is one of the more pristine lakes in a series of similar landforms greatly altered by pastoral dairy farming. The water level in the lake was lowered many years ago by cutting an alternative outlet stream. This left a large area of formerly lake bed, which has been farmed for many years. Some of the lake margin is already protected by a Queen Elizabeth II trust covenant and some of the lake margin has been previously planted in native plants by the Waikato Regional Council and funded by a conservation trust. The land is difficult to farm and not very productive. The current landowners and farmers are keen to restore a native plant community on the land, encouraged by a conservation covenant arrangement which grants consent to subdivide a number of residential sections. 59
THE FOREST FOR THE TREES continues to reestablish along with Machaerina spp. Nearby natural areas of vegetation: Nearby lake shore is dominated by manuka (Leptospermum scoparium), swamp coprosma/ hukihuki (Coprosma tenuicaulis), mingimingi (Leucopogon fasciculatus), fern (Hypolepis distans), tangle fern (Gleichenia dicarpa), baumea (Machaerina rubiginosa), M.teretifolia, M.arthrophylla, swamp blueberry (Dianella haematica) and bracken fern/rarauhe (Pteridium esculentum). The tall, rush–like emergent plants jointed baumea (Machaerina articulata) and kutakuta (Eleocharis sphacelata) grow in the shallow lake margins. The insectivorous forked sundew (Drosera binate), the diminutive Nertera scapanioides and the epiphytic native ferns hound’s tongue (Microsorum pustulatum subsp. Pustulatum) and sickle spleenwort (Asplenium polyodon) are also present. Kahikatea (Dacrycarpus dacrydioides), New Zealand flax/harakeke (Phormium tenax), cabbage tree/ti kouka (Cordyline australis), mingimingi (Leucopogon fasciculatus) and a small number of totara (Podocarpus totara var. totara) and swamp maire (Syzygium maire) have been planted in a narrow strip next to the eastern and southern lake shore. 1.7 Significant weeds The area is predominantly covered with gorse (Ulex europaeus), with significant areas of blackberry (Rubus fruticosus agg.). Chinese privet (Ligustrum sinense) has been prevalent in an area already cleared and planted next to the lake, but occasional seedlings still appear regularly. Grey willow has been common in the past but has been significantly reduced. This project, combined with recent work already done, has the potential to completely eliminate grey willow (Salix cinerea) from the lake surrounds and seriously reduce the risk of reinvasion. Royal fern (Osmunda regalis) which has become a serious threat in nearby wetlands
has been found in the vicinity occasionally, but was controlled each time it was identified. 2. Site objectives Because the site was previously shallow lake bed, and the nutrient status continues to be enriched by dairy farming, there is no opportunity to return the site to a previous, pristine state. Both raising the lake level and lowering the soil level through earthworks have been discounted. The introduced gorse (Ulex europaeus), blackberry (Rubus fruticosus agg.) and grey willow (Salix cinerea) will continue to thrive in preference to the wetland species currently and historically present on this site. Continuation of the lowered water table and current farming practices can be expected to lower the surrounding peat levels further, through oxidation of the peat. Because the lake was formed by a peat dam on one side, loss of this peat will eventually contribute to ongoing lowering of the lake level. Any attempt to establish low–stature wetland plants on the site without the shade provided by taller forest is likely to expose the site to dominance by taller weedy species. Both gorse (Ulex europaeus) and blackberry (Rubus fruticosus agg.) have continued to persist in the narrow lake margin planting already established, except where taller manuka (Leptospermum scoparium) provides sufficient shade. Ongoing control of these weeds on the site proposed for planting has been required and is a significant challenge to the present management of the property. The planted kahikatea trees (Dacrycarpus dacrydioides) can be expected to tolerate the winter waterlogged soil and out–compete the gorse (Ulex europaeus). In this situation it may be more vulnerable to summer drought than to the winter waterlogging. The objective of this project is to restore the kind of plant community which may have established in the present physical conditions 60
THE FOREST FOR THE TREES Pukemokemoke Reserve: Pukemokemoke is a small bush remnant 33km north north– east of this site. Milled for timber in the 1940s, then left to regenerate, with occasional incursions of grazing cattle, the site has recovered well, with a healthy range of species on a variety of habitats. The site is now a protected reserve with its own restoration programme, focused mainly on the eradication of Chinese privet. The lower slopes of the hill and the margins of the Mangatea Stream at Pukemokemoke provide some clues about the nature of primeval forest on the mineralised soil to the east and south of Maratoto. Kahikatea (Dacrycarpus dacrydioides) dominates the forest but matai (Prumnopitys taxifolia), titoki (Alectryon excelsus subsp. excelsus), totara (Podocarpus totara var. totara), pukatea (Laurelia novae–zelandiae), tawa (Beilschmiedia tawa) and pokaka (Elaeocarpus hookerianus) also contribute to the canopy. Kanuka (Kunzea ericoides) is present in open areas, as is karamu (Coprosma robusta), another coloniser, though it is not so common in the shade of taller trees. The understorey is made up of gahnia/ mapere (Gahnia xanthocarpa) in the wettest areas, with round–leaved coprosma (Coprosma rotundifolia), swamp mahoe (Melicytus micranthus), hangehange (Geniostoma ligustrifolium), putaputaweta (Carpodetus serratus), turepo (Streblus heterophyllus), white maire (Nestegis lanceolate) mahoe (Melicytus ramiflorus) and mapou (Myrsine australis) common. Around the margins, pate (Schefflera digitate) and the native fuchsia, known as kotukutuku (Fuchsia excorticate) are also found. Climbers including kohia (Passiflora tetrandra), supplejack/kareo (Ripogonum scandens), kaihua (Parsonsia heterophylla), pohuehue (Muehlenbeckia australis), and kiekie (Freycinetia banksii) are common. Ground ferns, climbing ferns and epiphytes are also found.
in the absence of other human influence on the site. That is to say, to restore to the site those species which might have once naturally dispersed there, and then established successfully given the current conditions on the site. On most sites, the obvious process is to identify a natural remnant on similar ground to use as a template. In this case, because the landform has been significantly modified, it is not possible to find such a remnant, so the alternative is to consider which native species might have been found in the vicinity — within dispersal distance — and predict the nature of the resulting native plant community. 3. Constructing a virtual reference ecosystem A reference ecosystem for this site is both interesting and complex. The purpose of the reference is to gain better knowledge of the plant species likely to have been found in the vicinity, on the adjoining low hills and peat bog, as well as how well those species might establish on the project site. Naturally, the first place to examine is the lake shore, where some native vegetation remains and is described above. The sites used for reference for the Waioteatua Stream project will contribute to our understanding. The Waipa Heights site has annually flooded swamp forest, which will also give us some idea of what will thrive on the site. It is useful to examine plant communities on other sites as well. Remnant native plant community on Lake Maratoto margins: The remnant native plant community nearby also contributes useful reference material for constructing a reference ecosystem. The shrubs found here will naturally disperse onto the new site over time, but the process may be usefully accelerated and weeds more effectively controlled if lessons are learned from the plants found in this area. 61
THE FOREST FOR THE TREES Moanatuatua Scientific Reserve: This small remnant of the natural peat vegetation of the district lies just 6km to the southeast of Maratoto. The peat vegetation is dominated by wire rush (Empodisma robustum) and cane rush (Sporadanthus ferrugineus). Shrubs include manuka (Leptospermum scoparium) and tamingi (Epacris pauciflora). The peatland ferns and small herbs at Maratoto are also found at Moanatuatua.
treatment and these will be sprayed in autumn with metsulfuron–methyl with wetting agent and marker dye. Both the marker dye and the surfactant are particularly important with gorse. The marker dye helps ensure the weed is completely covered, while no area is sprayed twice. The wetting agent is important to ensure the herbicide covers the plant well and adheres to the surface. In the spring, the whole area is sprayed again, focusing on the new shoots of each weed species, then a repeat in the summer. The summer spray will be done with triclopyr, again adding wetting agent and dye. The triclopyr has little effect on grasses and sedges, which will help suppress newly germinated weed seeds. The entire site will be progressively planted each winter, but the remaining unplanted areas will continue to be treated with herbicide in summer, when the ground is dry, to minimise regeneration of these weeds. Only occasional spot spraying is anticipated as the project progresses in the areas yet to be planted, but release spraying around the newly establishing seedlings will also be an important part of the project. Release spraying will continue in spring and autumn each year until a canopy is established and regeneration of these woody weeds is minimal and, more importantly, no longer a threat to the project. Nearby remnants of gorse (Ulex europaeus), blackberry (Rubus fruticosus agg.) and willow (Salix spp.) will also be controlled to reduce the possibility of dispersal from these. A close watch for royal fern (Osmunda regalis) will be maintained and any plants appearing will be sprayed with metsulfuron–methyl or dug out.
4. Weed management plan Ultimately, establishing a resilient native plant community is the key to weed control on this site. But for this to happen, current weeds must be controlled. Very effective aerial spraying for gorse (Ulex europaeus) was carried out in 2005. Ground–based follow–up spraying has occurred on the site several times since then, with grey willow (Salix cinerea) seedlings being cut down and the stumps painted with herbicide. Despite this level of attention, gorse (Ulex europaeus) continues to dominate the site, with blackberry (Rubus fruticosus agg.) still rampant too. It is not clear whether this persistence is due to reinvasion by seed from outside the site, viable seed in the ground continuing to germinate, production of seed by a few remaining plants, or re–sprouting from the bases of plants which have only partially died back. It is probably a combination of all of these. The size of this project requires the most economical approach. The maximum possible plant spacing will significantly reduce the cost, but this will require very good weed control. For this reason, the project will be approached progressively over ten years. This approach has the added benefit of allowing trials of various techniques and plant species, with time to implement what is learned. Where possible, the gorse (Ulex europaeus) and blackberry (Rubus fruticosus agg.) will be mown by tractor and rotary slasher. There will, however, be some weeds too large for this
5. Planting Plan Because this is a unique site, with no close equivalent, an important component of this planting plan will be the exploration and trialling of a range of species and approaches. This is also a very large site with a limited budget. Priority will be given to re–establishing a limited number of species contributing the 62
THE FOREST FOR THE TREES most to the restoration of natural patterns and processes. Because of the size of 14ha, the site will be divided into eight areas, treated progressively over time. This allows time for effective weed control prior to planting, spreads the cost over a decade and provides an opportunity to trial a range of strategies and implement useful solutions which may become apparent over time. Kahikatea (Dacrycarpus dacrydioides) and cabbage tree/ti kouka (Cordyline australis) will dominate planting, as both tolerate the variation in soil moisture found on the site. Being trees rather than smaller plants, each specimen has the potential to make a significant contribution to the site. Manuka (Leptospermum scoparium), a natural coloniser of the area, will be propagated by the distribution from the nearby lake margin of small branches bearing capsules full of seed. This approach has had success on other projects, but requires very good weed control to work well. A single shrub species will dominate the understorey. Coprosma X cunninghamii, a naturally occurring hybrid of Coprosma robusta and Coprosma propinqua, is very tolerant of wet conditions and frost, is quick growing, reasonably drought tolerant and seed is plentiful. Dominance by a single species is uncommon in natural areas. In some situations, greater shade, drier or wetter areas may advantage other species, but the vigour of this species makes it a good choice in most situations, particularly during the early years of the project. The few specimens of successful trial species can be expected to regenerate naturally and disperse across the site over time.
expectation of a worthwhile outcome and it is useful to outline this. Attempts have been made to control gorse (Ulex europaeus), blackberry (Rubus fruticosus agg.) and grey willow (Salix cinerea) on the site by mowing, mulching, spraying and grazing over several years, yet left uncontrolled, the weeds, and gorse in particular, persist. Similar habitats in the area seem to eventually progress to a grey willow–dominated system, with some persistent gorse and blackberry in open areas. The weed control planned is expected to suppress these weeds sufficiently to allow the planted natives to establish. Whether this is sufficient to prevent new seedlings appearing, or whether ongoing control will be essential until a dense native canopy is established, remains to be seen. Cabbage trees/ti kouka (Cordyline australis) will be the quickest to establish and grow. Within 10 years of planting, they will have developed forked trunks and set seed. At 6m spacings they will not close a canopy, but will be tall enough for any gorse (Ulex europaeus) to no longer pose a threat. After a decade, the kahikatea (Dacrycarpus dacrydioides) will at last begin to thicken its foliage and contribute to shade. Occasional trees will begin to set seed at this stage, although many individuals will wait for a few more years before this happens. If the weed control has been effective, manuka (Leptospermum scoparium) seedlings will begin to appear after the first year of planting, from the “slash” spread around at the time of planting. The coprosma shrubs are to be planted no closer than the taller tree species, so will not form a sub–canopy on their own; natural regeneration is necessary for this to happen. After four or five years, viable seed will begin to appear, but it will be a couple of years later 6. Trajectory that seedlings begin to emerge above the As the project develops, a number of things grass, rushes and broad–leaved herbs. will happen. Though it is difficult to accurately Each year,100 trial plants will be planted. predict the outcome of the restoration work, These might be wetland shrubs, herbs and the work has been planned with a reasonable sedges for the particularly wet areas, they 63
THE FOREST FOR THE TREES Mount Te Aroha Timelines, continuums and gradients Developing a virtual reference ecosystem for the lower slopes of Mount Te Aroha
might be understorey shrubs for the drier margins, or they may be some of the species already found along the lake margins, like tangle fern (Gleichenia dicarpa), mingimingi (Leucopogon fasciculatus) or turutu (Dianella nigra). These 100 plants, spread over thousands of square metres, are not enough on their own to contribute very much to the plant community, but those which grow well will be planted more often in future and their offspring in time will disperse across the site. Eventually a canopy of kahikatea (Dacrycarpus dacrydioides) will develop, with cabbage trees/ti kouka (Cordyline australis) wherever the ground is particularly wet or the kahikatea are stunted. There will be occasional other tree species and an understory dominated by Coprosma X cunninghamii, but also including some of the trial species evaluated. Gorse, blackberry (Rubus fruticosus agg.) and grey willow (Salix cinerea) should be scarce because the environment is too shady for them.
The Te Aroha site has a unique climate with winter frost above and below. The historic site of the Edwardian spa in Te Aroha is a focus for varying interests. The historic buildings of course warrant protection, the mineral waters are a significant attraction and the mountain bike and walking tracks are growing in popularity. But the privet hedges and other exotic trees dating from the gold mining days are a different matter. The lower slopes of the mountain were cleared of native bush, at least by the time gold mining started, so the introduced exotics had free range over the site. Privet trees attract tui to feed on the berries, but this results in the privet being spread all over what was once native bush. The plan adopted was a collaboration between community members focused on protecting and restoring the native character and the Matamataâ€“Piako District Council, with a mandate to protect the cultural heritage. Every site is unique: no two places on the planet have identical soil, slope, aspect, climate or history. Because of warm mineral springs and gold mining, this site at the western foot of Mount Te Aroha has a long history of human occupation.
Monitoring and Reporting This will be an interesting project to watch because it is divided into eight similar areas, which will get very similar treatment, so by the eighth year, there will be examples of areas just planted and the opportunity to compare them with other areas that have progressed significantly since planting. Monitoring will be particularly important here because there will be the opportunity to apply anything learned to the next areas to be treated. Monitoring will also be important because the design includes the intention to trial a range of species, which implies careful observation to see if they respond as expected.
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The native planting is bravely competing with weed regeneration. kawakawa (Piper excelsum), twiggy coprosma (Coprosma rhamnoides) and C.areolata. Aside from the presence of kahikatea (Dacrycarpus dacrydioides) and absence of pohutukawa (Metrosideros excelsa), this looks very much like coastal forest. To get a better idea of the natural flora of this site, and how it fits into the wider landscape, it is interesting to look at the forest to the north and south along the base of the range, the river flood plain and up to the summit. We can glean what we can from past accounts of the native vegetation of the area. The Kaimai Range, where Te Aroha is situated, runs roughly north to south. Some mainly coastal species can be found around Te Aroha, but only within a limited altitude range. Along the hills to the north, the coast at the Firth of Thames is over 40km away. Across the range to the east, the Tauranga Harbour is about half that distance. Pohutukawa (Metrosideros excelsa) is common only within
Successive generations of human occupants have left an indelible mark on the flora here. Today the site is dominated by tall pine from California and eucalyptus and wattle from Australia; remnants of the gold mining days. Trees and Chinese privet, Japanese honeysuckle (Lonicera japonica) and wandering Jew (Tradescantia fluminensis) have all escaped from local gardens and now run rampant; far more than any native species. Pampas (Cortaderia jubata and C. selloana) dominates some of the margins. The tallest native tree on the site is kanuka (Kunzea robusta), a characteristic of a very young forest. There are young kohekohe (Dysoxylum spectabile), karaka (Corynocarpus laevigatus), puriri (Vitex lucens), totara (Podocarpus totara var. totara) and kahikatea (Dacrycarpus dacrydioides) nearby. Native understorey consists of mahoe (Melicytus ramiflorus), hangehange (Geniostoma ligustrifolium), rangiora (Brachyglottis repanda), 65
THE FOREST FOR THE TREES a few kilometres of the coast. Kohekohe (Dysoxylum spectabile) occurs along the range for about 40km further south and further, along the coast. Puriri (Vitex lucens) is common around Te Aroha and for another 25km further south along this range. Karaka (Corynocarpus laevigatus) is common around the coast, but found along the range only as far as Matamata, 30km to the south. Rewarewa (Knightia excelsa), common throughout the North Island, and kahikatea (Dacrycarpus dacrydioides) and totara (Podocarpus totara var. totara) both common nationwide, grow nearby as well. If we look at the forest on the level ground along the Waihou River flood plain, it is dominated by kahikatea (Dacrycarpus dacrydioides), with pukatea (Laurelia novaeâ€“ zelandiae), matai (Prumnopitys taxifolia), titoki (Alectryon excelsus subsp. excelsus) and pokaka (Elaeocarpus hookerianus) found there too. If we look further up the mountain, rimu (Dacrydium cupressinum) and tawa (Beilschmiedia tawa) forest is common, with miro (Prumnopitys ferruginea), totara (Podocarpus totara var. totara), hinau and pukatea (Laurelia novaeâ€“ The planting is getting too tall for zelandiae) present. On ridges where the soil is most of the weeds. leached, kauri (Agathis australis) and tanekaha (Phyllocladus trichomanoides) forest occurs in small pockets. Near the summit, the canopy is lower and consists of silver beech, almost at its northern limit, as well as red beech (Fuscospora fusca), tawheowheo (Quintinia serrata), tawari (Ixerba brexioides) and neinei (Dracophyllum latifolium). On the lower slopes of the mountain, where frosts may be less severe than either higher up or down on the plains, there was once a unique plant community, reminiscent of coastal forest and quite different to that found anywhere else. Access to the internet has helped us readily access early accounts of the flora of the area. The Transactions and Proceedings of the Royal Society of New Zealand (including, prior to 1933, the Transactions and Proceedings of the New Zealand Institute) are available and 66
THE FOREST FOR THE TREES searchable online. The New Zealand Plant Conservation website, www.nzpcn.org.nz, also makes readily available lists of plants from many past surveys. An account of the botany of Te Aroha Mountain was made in the Transactions and Proceedings of the New Zealand Institute 1884, 10 years after the opening of the local goldfield. This account helpfully indicates the part of the mountain where each species can be found, so that a picture of the flora, from the wetlands and riverbanks to the summit can be drawn. Name changes during the intervening years may present a challenge, and some species may be more widely distributed on the mountain than recorded, but it is a good guide to what was found there soon after the goldfields opened. The author refers to those species found further north along the range, but absent on the mountain, helping to avoid mistakenly translocating inappropriate species. The restoration plan will focus particularly on controlling the garden escapee weeds now so prevalent on the site. Some of the larger trees, like the pines and eucalyptus, are less likely to regenerate in shady places and offer some protection from the elements, so will be retained. The two privet species, however, produce a lot of seed and their control is essential to prevent them spreading. The wandering Jew (Tradescantia fluminensis) has the potential to spread throughout the site and interrupt natural regeneration of most native species, so a programme of intense manual and herbicide control is recommended. Japanese honeysuckle (Lonicera japonica) threatens to scramble over newly planted shrubs and to shade and distort them, so will be either pulled out, or, if too large, cut off at the base, then sprayed with herbicide. Colonising species like karamu (Coprosma lucida) and kanuka (Kunzea robusta) are found among the exotics, as are seedlings of the native trees found there. Many of the understorey, scrambling, perching and
ground cover species are found close by. Given time, the site could be expected to recover naturally once the weeds are controlled, but some planting will be done to speed up the process. This is because the site is adjacent to the Edwardianâ€“era Te Aroha Domain, giving it a high public profile. Each of the tree species recorded from the area will be planted on the site. Because the area is particularly sheltered by the nearby forest and exotic trees, weed control will be intensive and frosts are expected to be mild, few colonising plants will be required. A few kanuka (Kunzea robusta), cabbage trees/ti kouka (Cordyline australis) and shining karamu (Coprosma lucida), though, will be included to provide shelter where it is needed. The soil is heavy clay derived from weathered basalt. Because of the steep slope, drainage is still good and the site is vulnerable to drying out. The understorey will consist of thinâ€“leaved coprosma (Coprosma areolata), twiggy coprosma (C. rhamnoides), shining karamu (C. lucida), rangiora (Brachyglottis repanda), heketara (Olearia rani), ti ngahere (Cordyline banksii) and mapou (Myrsine australis) on the drier areas. In dry, shady areas, there will be kawakawa (Piper excelsum) and pate (Schefflera digitata). Kotukutuku (Fuchsia excorticata) will predominate where the soil is permanently moist and shelter from frost is provided. Hangehange (Geniostoma ligustrifolium) and mapou (Myrsine australis) will also be planted in all of these situations. Seed from each of these species can be readily collected from nearby plants and propagated for the project, avoiding the possibility of introducing new genetic lines into the area. Trajectory The few kanuka (Kunzea robusta) and shining karamu (Coprosma lucida) are expected to grow quicker than other species and so have an influence bigger than their numbers would suggest. In the wetter places though, the pate and kotukutuku (Fuchsia excorticate) 67
THE FOREST FOR THE TREES Ngaroto/The Lake Ecological restoration is very much in its infancy. We learn so much from past mistakes, but restoration is a very long term project. Opportunities to look back over decades are rare, so Ngaroto, first planted in the 1980s, has valuable lessons for us all. Waipa District Council has had a longâ€“term interest in the site. Over the years, a number of approaches have been tried and reviewed. The council has engaged a number of consultants and experts, community members have given their time and experience generously, funding has been sought and channeled from a number of community funds and at each step lessons have been learned. Ngaroto was formed when silt deposited by the river dammed the channel and diverted the river. The river has changed course many times since then, so the outlet stream now flows many miles to reach it. It is in the nature of lakes to eventually fill with sediment and, given time, become wetlands. Since the forest surrounding the lake has been cleared and the land converted to pasture this process has accelerated, adding nitrogen and phosphorus nutrients as well. To protect the lake, the whole catchment needs careful planning, with careful balancing of nutrient inputs and outputs and the exclusion of stock from waterways. Silt traps and denitrifying wetlands must intercept water as it enters the lake. A useful first step would be to exclude cows from the lake shore and establish native plants along the margins. New Zealand flax/ harakeke (Phormium tenax) is a useful native plant and an obvious choice. It will grow almost anywhere and has the ability to form rafts with its roots and colonise shallow water. It will grow on steep cliffs, tolerating frost and wind well. Flax also produces large amounts of nectar to attract pollinating birds. Its only weakness is its intolerance of shade. It was this failing that ensured its demise after it was planted over a large area, all around the lake. Because, although it will
will grow nearly as fast, as will the kawakawa in sheltered, shady places. Kanuka (Kunzea robusta) is expected to be the tallest tree for several decades but it will not be dense enough to completely dominate the canopy as it might do in a more natural succession. Over time, the other tree species will overtop the shrubs, significantly changing the appearance of the site and eventually even shading out the kanuka .This will begin to happen at about 10 years with the smaller shrubs, but may take 100 or more before the kanuka is shaded out. Long before this happens however, nearby native shrubs and smaller plants are expected to disperse onto the site, so a whole range of native seedlings and ferns can be expected to arrive naturally. So, too, unfortunately, will the weedy species. Monitoring Watching for, and controlling privet and honeysuckle will be the focus of monitoring and management. Once the planting gains sufficient height, honeysuckle will no longer be a problem but privet will always need to be under surveillance. If the wandering Jew (Tradescantia fluminensis) is not completely controlled before planting begins, a vigilant lookout must be maintained to continue the control and make sure it doesnâ€™t creep back in.
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Part of the Ngaroto project, young manuka in the foreground with collapsed manuka beyond. There is only one possible explanation for this: it dies young. If it is not shaded out by taller trees, or topples over in soft moist soil, manuka succumbs to stem–boring bugs at about 20 years. So at Ngaroto, after two decades, the manuka started dying; just the odd tree for a start, then, eventually, large areas of them. In earlier times, the whole catchment was covered in tall, rich forest and if this was still the case, a succession of native plants would have replaced the manuka. Now, however, manuka was replaced with blackberry (Rubus fruticosus agg.), honeysuckle and bindweed (Calystegia spp.). The challenge for the third restoration plan for Ngaroto has been to establish a plant assemblage which will last indefinitely and be resistant to weeds. If possible, it would be advantageous if the plants were native to the area and able to reinforce nearby populations, provide stepping stones to help overcome fragmentation and provide habitat for native birds. The restoration plan prescribes the succession to mature forest in those areas where the manuka (Leptospermum scoparium) canopy is still healthy.
grow anywhere, it only reaches about 3m, so was easily overgrown by scrambling weeds like blackberry. The flax and weeds were removed and replaced with manuka (Leptospermum scoparium) and a range of native trees and shrubs were planted on some small areas too. Planting was spread out over several years, starting near the road end and progressing clockwise around the lake. The Manuka (Leptospermum scoparium), like the flax, will grow in a wide range of soil and climate conditions. Manuka grew to a height of around 8m and did a pretty good job of shading out the weeds. The other native trees—mostly kahikatea (Dacrycarpus dacrydioides)—and some shrubs worked well with the manuka, while other native plants established under it. Mahoe (Melicytus ramiflorus) and several species of tree fern had probably persisted in small numbers around the lake since the area was cleared, and the manuka (Leptospermum scoparium) provided the ideal environment for them to flourish. Manuka (Leptospermum scoparium), like flax, has limitations. It grows quickly, but never to a great size. 69
THE FOREST FOR THE TREES We do have some idea of the nature of forest which establishes on environments like the hills surrounding the lake. We also have some idea of the kind of plant community we might expect on the damp, low–lying ground close to the lake. We can learn this from the reference sites we investigated for previous case studies. These reference sites also give us some idea of how succession proceeds on a site like this. So, given a site, dominated with aging manuka (Leptospermum scoparium) with an understorey of mahoe (Melicytus ramiflorus), tree ferns and some ground ferns, we can then put together a plan for the next stage in succession. The plan will involve the removal of herbaceous weeds like inkweed (Phytolacca octandra), then the planting of appropriate species. There is no need for colonising species; the manuka has already performed In the shade of manuka young that function really well. Frost–tender and slow–growing, shade– pukatea and mahoe thrive. tolerant species can be planted now that there is such a dense canopy protecting them from frost and weeds. The manuka canopy also allows for much less dense planting than would otherwise be needed, because weeds are much less of a threat. This approach of initially planting a monoculture of Manuka (Leptospermum scoparium), then following it up with later successional species has merit. Planting the manuka quickly establishes cover of native plants, excluding weeds, starting the process of growing a forest. Often the most suitable plant species for a project are not available, or at least, not appropriately ecosourced. Even exploring reference sites and preparing a detailed plan can take time, so planting the manuka in this case or alternatively, as on some other sites, a selection of colonising species, can buy time to execute the restoration well. Manuka is vulnerable to boring bugs. This will, however, depend on planting other species in time to have them well established before the colonisers begin to fail. 70
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Only sparce planting is required below the still healthy manuka.
The ferns have arrived naturally, the pokaka will succeed the manuka.
Planted more than twenty years ago, these manuka are nearing their natural life span.
THE FOREST FOR THE TREES Mangarata Stream Every project has its unique features, but the Mangarata Stream project provides opportunities that few other projects do.
extended period prior to planting. Sometimes this can be spread over several years, with the opportunity to apply lessons learned as they become apparent.
Mangarata site from above. The potential of all projects is largely determined by the project funders, who typically require projects to be conceived and executed within a short time frame. This commonly means that planting will be done only once at a particular site and consequently restricted to plants that are suited to exposed conditions. Sometimes this includes some canopy trees and occasionally understorey shrubs, but the potential for the project is often limited. The Mangarata Stream project has been funded by the Waikato District Council for over 10 years, more recently supported by Waikato River Authority funding. Planting is done each winter by students from Te Kura Kaupapa Maori O Bernard Fergusson, the local primary school. This means that weed control preparation can be done over an
The arrangement allows for not only initial planting into new ground, but also supplementary planting, with species better suited to the conditions created as a canopy develops. This progressive approach to planting also allows for lessons to be learned and applied from the successes and challenges that become apparent over time. Plants that thrive on the site are used more often, while those vulnerable to the conditions are avoided. The project also has the advantage of nearby bush in the scenic reserve, which provides some guidance regarding appropriate species and their place in the successional sequence. Each year, the students plant 200 seedlings. The first plantings were spaced 1m apart and initially comprised mainly colonisers 72
THE FOREST FOR THE TREES like kanuka (Kunzea ericoides), karamu, ribbonwood/manatu (Plagianthus regius subsp. regius) and cabbage trees/ti kouka (Cordyline australis). A few hardy understorey shrubs like karamu and trees like kahikatea, totara (Podocarpus totara var. totara) and matai (Prumnopitys taxifolia) were also included. Subsequent years extended the plantings with similar species, but as the canopy developed and the planting approached the stream bank, the approach changed. Canopy species like titoki (Alectryon excelsus subsp. excelsus), and pukatea (Laurelia novaeâ€“ zelandiae) were planted under the establishing canopy, along with more understorey like mapou (Myrsine australis), mahoe (Melicytus ramiflorus), kawakawa (Piper excelsum), kawariki (Coprosma grandifolia), thinâ€“leaved coprosma (C.areolata) and C.rhamnoides, which would otherwise have struggled to compete with the grass or been damaged by frosts. Anticipating the response of each species to the environment is not easy and mistakes will always be made, but can be an opportunity for learning. Kohekohe trees were planted under kanuka (Kunzea robusta) canopy in the winter of 2015, but all succumbed to the particularly severe frosts that year. Kohekohe is common along the river and in the nearby ranges, so will be tried again as the canopy becomes denser. It is an important tree because its seedlings will grow in very dark conditions under other trees and its fruit is an important food source for birds in winter when food is scarce. Future years will see the reintroduction of tree ferns like mamaku (Cyathea medullaris) and ground ferns like pukupuku (Blechnum parrisiae syn. Doodia australis), Thread fern (Blechnum filiforme) and shining spleenwort (Asplenium oblongifolium) in the drier areas and hen and chicken fern (Asplenium bulbiferum) in wetter ones. A range of appropriate sedges is being propagated to help cover the
After a few years the habitat is suitable for ferns to begin to appear. ground along with herbaceous species like parataniwha (Elatostema rugosum) and pratia (Lobelia angulata). The addition of these species not only helps secure them locally, but also helps deter exotic weeds that would otherwise thrive.
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Alder: Unlike crack willow, alder sets seed.
Alder: European alder, common along waterways.
Beggarâ€™s ticks: Bidens frondosa, beggars ticks takes over newly disturbed waterways and wetlands. Blackberry: Sweet and tasty but those fruit carry seeds.
Blackberry: This grows particularly well in wet areas
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Clearing the slate Glossary of weeds
his chapter gives details of the weeds encountered in these case studies and options for their control. Having considered a range of tools for weed control, it may be helpful to investigate the weeds encountered on each of the case studies and explore options for their control. This is not a comprehensive list of weeds encountered in restoration projects anywhere, but rather an illustration of the kinds of things we need to understand about weeds we may be working with.
These barbs ensure that any mature seeds which come in contact with clothing remain there, making it a very unpleasant customer to deal with. This annual member of the daisy family is not very tolerant of shade, so is not a long–term threat to any planting project. But it can grow very densely in well–lit areas and when the seed ripens, it can make them very difficult to access. Control: Individual plants can be pulled out by hand. Large areas respond well to most herbicides. Control should really be done early in the spring when plants are small, then Alder (Alnus glutinosa) repeated until mid–summer. Once an area has The alder was introduced as an ornamental been planted, hand pulling of this 2m–high tree, but has very successfully naturalised annual will be necessary where it overtops since 1914 because of its prolific seeding and the native seedlings until sufficient shade is high tolerance of flooding. Rumour has it that established. its value as firewood encouraged its planting along the Waikato River in the steamboat days, Blackberry (Rubus fruticosus agg.) but the alder’s fecundity alone is sufficient to Blackberry has been naturalised in New explain its occurrence all along the river and Zealand since 1887. It thrives in a wet climate associated wetlands. After crack willow, this and tolerates very wet soil. The thick, tangled is the most common tree on the Waioteatua mass of spiny stems prohibits access to plant Stream restoration site. Its prolific seeding will or even to spray weeds. Once a close native make it a priority for control. canopy is established, conditions are too Control: Smaller seedlings can be effectively shaded and blackberry fails to thrive. Other controlled by the spraying regime prescribed weeds like wandering Jew (Tradescantia for other weeds. The taller trees can be fluminensis) can persist under blackberry, easily controlled by the drilling and injecting making its control necessary. method described earlier. Control: During spring and summer when growth is vigorous, blackberry is particularly Beggars’ ticks (Bidens frondosa) vulnerable to most herbicides. Two–metre This plant has been naturalised since 1907. high blackberry can seem daunting to spray, The name Bidens refers to the two tooth–like especially when it covers a large area. Lengths projections with tiny barbs along their length. of timber or ladders laid down in the mass 75
THE FOREST FOR THE TREES of canes can help provide access to spray through the interior of a large site. In order to speed up access to weeds growing under the blackberry, it may be necessary to mow, mulch or slash the sprayed canes. Because it is so intolerant of shade, a practical alternative to using herbicide would be to cut tracks through the blackberry and plant shade tolerant native tree and shrub species. The result would not be dramatic or instant but over time the trees would shade out the blackberry. Box elder (Acer negundo) Box elder: The maple like leaves of box elder are Box elder was first recorded naturalising becoming more common along rivers. in 1983 (Flora of New Zealand Vol. iv). In the short time since then, it has become well established on the Waioteatua site, with prolific seedling growth beneath the mature trees. This apparently rapid establishment is convincing evidence that box elder must be controlled. Control: The carpet of seedlings on the ground can be easily sprayed along with other weeds. Small saplings up to 30mm in diameter can be cut with loppers then poisoned at the same time as larger specimens are drilled and injected. Several larger specimens have fallen over and continued to grow, something Box elder is spreading quickly and will grow that will present a challenge to drilling and taller than the willow. injecting. This may need to be repeated if not completely successful the first time. Chinese privet (Ligustrum sinense) and tree privet (L. lucidum) These two ornamental trees escaped from cultivation in the 1950s. Their tolerance of shade and prolific seed production make them very effective colonisers of unmanaged land and recovering native bush. Only Chinese privet is found on the Waioteatua Stream and Lake Maratoto projects, but both species dominate the Te Aroha Domain site. Fruit from both species is an important food source for both native and exotic birds. Pheasant hunters are reputed to have in the past carried a pocketful of privet seeds around, Chinese privet. dispersing them wherever a likely place for 76
THE FOREST FOR THE TREES new privet might be. In Te Aroha the tree privet in the domain attracted tui to town, so any suggestion to control privet was resisted by a faction of the community, but once they realised privet seeds would be carried back into the bush, an agreement was made to replace the privet with suitable native food sources. Control: Small privet can be controlled by spraying with triclopyr or metsulfuron– methyl. Glyphosate has only limited effect, so a very thorough coverage is necessary. Taller saplings can be cut and poisoned. Larger trees can be easily controlled by the drill–and–inject Tree privet: Delicious but deadly these fruit carry the genes for privet to every hedge and all the method. Very large areas of exclusively Chinese bush in the district. privet at Pukemokemoke Reserve, a private bush reserve in the northern perimeter of the Hamilton basin, have been controlled by cutting and mulching with large machinery. Adjoining areas with mixed native trees and privet still require more intensive attention but the quantity of seed produced annually has been drastically reduced. Convolvulus/bindweed (Calystegia sepium) Convolvulus occurs worldwide. The commonly encountered convolvulus here is probably native, but nonetheless a threat to newly–established plantings. It scrambles over other plants, or in fact anything it can, to get into the sunlight. The habit of spiraling around objects gives bindweed its name. Cabbage trees/ti kouka (Cordyline australis) are some of the most vulnerable victims. As the bindweed stems grow upwards, they encircle the whorl of leaves at the top of a cabbage trees, binding them together. This prevents them from opening to catch as much sunlight as possible, but more importantly, the tightly bound leaves cannot dry out so are vulnerable to rot. Bindweed not only binds leaves and branches together but can even pull the growing tip of a tree or shrub over, significantly slowing down its growth. Bindweed dies down each winter and puts on new growth in the spring and summer.
Convolvulus/bindweed: The aptly named bindweed has taken over this site planted about ten years ago.
THE FOREST FOR THE TREES Seed is set and it grows well from these but the fleshy rhizomes also persist underground ready to initiate new growth in the spring. Control: Bindweed, being soft tissue is very vulnerable and responds quickly to most herbicides. But because it is usually found growing over other plants, it must be dealt with very carefully. Spraying the newly emerging shoots early in spring and persistently following up is the most productive approach. This is only necessary for a few years after planting. Once a tall canopy is established, the conditions no longer favour bindweed and it ceases to be a problem. This reinforces the Convolvulus/bindweed: Spot the native tree approach of restoring the tallest and densest hidden under this mass of bindweed stems. forest that the site will sustain. Crack willow (Salix fragilis) Crack willow is the most common tree along many of our rivers. Introduced in the 1880s for erosion control, willow quickly spread to, or was planted along rivers all over the country. Most, if not all, crack willow in the wild are male so only hybrid seedlings are found. Regeneration and dispersal happens as a result of branches and twigs being carried along waterways. These break off easily and readily develop roots when they come in contact with the ground or water. Even large trees which become dislodged in floods can settle and grow roots in a new location. Because willow roots trap sediment, they can significantly modify the riverbank, creating gentle sloping river margins, frequently flooded during the wetter months and inhospitable to most native species. Once native forest has reâ€“established along the waterway, control of willows may be necessary to reinstate the natural form and function of the river. Control: The same as grey willow (Salix cinerea), but because it doesnâ€™t set seed, because of the importance in controlling erosion of riverbanks and because of the contribution willow can make to creating a suitable environment for native forest, advantages of control must be carefully
Convolvulus/bindweed: Bindweed may keep the bees happy but the struggling native tree beneath is not amused.
Crack willow: Only male crack willows are found in New Zealand. 78
THE FOREST FOR THE TREES balanced with reasons for retaining it, at least in the short term. Willow seldom grows more than 15m tall and at that height may in time be overshadowed by regenerating native forest. Gorse (Ulex europaeus) Introduced as a hedge plant but no doubt spread along with grass seed, gorse was naturalised in New Zealand by 1867. Like other members of the pea family, gorse fixes nitrogen in its roots, allowing it to tolerate infertile soil, like peatland. Although it burns readily, gorse will resprout from the roots and seeds which last well in the ground and are well adapted to thrive in the conditions resulting from fire. Gorse is not very tolerant of shade and quickly diminishes once overtopped by taller vegetation. For this reason, gorse is more of a problem in pasture or wetlands than in regenerating forest, where it may even provide valuable protection from wind and frost. Control: Herbicide spraying is the usual method. Because the leaves are modified to form spines, thorough coverage is difficult. Wetting agent or surfactant should always be used and great care should be taken to ensure that the whole of every plant is well covered. Alternatively, main stems can be cut and the cut surface painted or pasted with a mixture similar to what is used for drilling and injecting. Thickened herbicide pastes of either picloram or glyphosate are also available. Picloram should be avoided because any small amount dropped accidentally on the ground can affect surrounding vegetation.
Crack willow: Willows now line most rivers in the pastoral landscape.
Gorse: A common sight, gorse growing along a fenceline.
Grey willow (Salix cinerea) Grey willow comes from Western Europe and North Africa and was first naturalised here in 1925. Since then, it has spread to most of the country where it dominates some wetlands. Like wandering Jew (Tradescantia fluminensis), grey willow is a particularly serious weed because in many situations, native vegetation will not outâ€“compete it. Grey willow: This weed dominates most Grey willow is prevalent in swamps and the wetlands. 79
THE FOREST FOR THE TREES margins of peat bogs, where soil is less fertile than wellâ€“drained surrounding ground, but not in pristine peat bogs, where the substrate is waterlogged and extremely infertile. Control: Usually by aerial spraying or drilling and poisoning. Aerial spraying is preferred for large areas where there is little native vegetation and little risk of water contamination. Drilling and poisoning is very labour intensive because of the large number of stems in a small area, horizontal stems and swampy ground. Control is targeted to the appropriate species, so this can be a useful approach where native plants in the same area are recovering well and must be protected. An alternative to these methods is ringâ€“barking and poisoning, which has a similar effect to drilling. Cutting down and poisoning the stumps may be quicker than drilling but is not recommended because the felled tops of the trees may not only reâ€“sprout but also damage regenerating natives and impede access in the future. Mechanical removal using earthmoving machinery may be an option which gives immediate impact but it may be devastating to existing native plants and dislodge silt into waterways.
Grey willow: Buds in spring.
Hawthorn: Overlooking Whangapae.
Hawthorn (Crataegus monogyna) Hawthorn was first introduced from Europe and naturalised by 1899 and remnants of old hedgerows and occasional naturalised specimens still occur in unmanaged areas. Control: Hawthorn does not readily establish or spread in shaded sites so is no more than a minor nuisance in a restoration project. In some cases old specimens may provide valuable shelter to help establish more vulnerable native trees and shrubs. Seedlings are rare on the projects discussed here, and if control is considered, necessary drilling and poisoning is the most convenient method. This eliminates the need to remove the dead Hawthorn: Closeup of the flowers and leaves of tree and may provide some temporary shelter hawthorn in October. for more sensitive species. 80
THE FOREST FOR THE TREES Japanese honeysuckle (Lonicera japonica) Naturalised in 1926 from garden plants, Japanese honeysuckle has followed human habitation across the country in all but the driest, forested or mountainous areas. Being a climber, able to develop roots wherever the stem touches the ground, and producing fruit attractive to birds, Japanese honeysuckle is well adapted to invade disturbed natural areas, persist there and exclude native plants. If we plant native trees and shrubs into an area where honeysuckle grows, at the very least, the honeysuckle will quickly grow over these, shade them Japanese honeysuckle: Duelling with willow. and possibly bend over the growing tip, so that establishment of a native canopy is significantly slowed. More likely, the honeysuckle will completely prevent the establishment of native plants. Control: Total control before planting is essential. Because it grows high into any existing canopy, this is no easy task, especially if the trees it is growing over are to be retained. Cutting all stems just above ground level and again at a convenient chest height is a great way to ensure all stems growing up into trees are dealt with. There is no need to remove these. They will take a while to decay, but in the meantime, new growth in the trees they Japanese honeysuckle: Flowering. are growing over will emerge and the old climbers will be insignificant. Honeysuckle is easy to pull out, but the inevitable new growth can also be sprayed on the ground without risk of collateral damage. Most herbicides being used on the project for other species will be effective. Japanese walnut (Juglans ailantifolia) Japanese walnut was introduced as an ornamental tree and first officially recorded naturalising in 1983. This tree has become common along waterways, which no doubt help disperse the large nut. It is the prolific production of this nut which makes this tree so invasive. Japanese walnut: Where willows are absent, Drilling and injecting is quite satisfactory these walnuts come to dominate stream sides. control for larger trees. 81
THE FOREST FOR THE TREES The seedlings can be cut with loppers and the cut stump poisoned with the same material used for injecting. Jasmine (Jasminum polyanthum) Jasmine was naturalised by 1980 and forms dense mats across open ground, thickly enshrouding any tree it has the opportunity to grow over. Where it has established, jasmine has the potential to dominate all other weeds. Only the poor dispersal, mostly by layering or occasional cuttings, limits its distribution in the warmer parts of the country. This is a difficult plant to control effectively. Control: When jasmine grows over trees, cut off the stems at ground level and again at chest height. The regrowth from the ground can be sprayed with metsulfuron–methyl. When growing along the ground, repeated spraying with metsulfuron–methyl, with mechanical mowing or mulching to remove dead material in between each spraying episode. Repeat spraying as soon as new leaves appear and continue until no more regrowth appears.
Jasmine: Don’t be fooled by the attractive flower, jasmine is a real pest.
Wandering Jew (Tradescantia fluminensis) Originally from Brazil, wandering Jew was first naturalised in New Zealand in 1916. Since then, it has spread widely wherever it is damp and protected from frost. Wherever people have dumped fridges, mattresses and old bikes, wandering Jew can usually be found. But when the fridges, mattresses and bikes have rusted and rotted, the weed will still be spreading. In New Zealand, wandering Jew doesn’t set seed, rather the succulent stems sprout roots at every node. Stem fragments will float down rivers and spread wherever floodwaters reach, so this is commonly a plant of riparian margins and unofficial rubbish dumps. Although slow to spread, this is a very persistent weed. Combined with an ability to thrive in very shady places, these attributes make it a serious threat to lowland forests, particularly those close to roads and rivers. The dense mat which can often be more
Jasmine: Flowering. 82
THE FOREST FOR THE TREES than half a metre thick is impenetrable to most native plant seedlings. This means that wherever wandering Jew is found, native vegetation diminishes in favour of trees like crack willow, which can sprout from flotsam branches, and climbers like Japanese honeysuckle (Lonicera japonica) and jasmine. In this respect, wandering Jew can be considered to be an ecosystem engineer. Control: Some weeds can be completely eliminated as a result of shading by a dense, native plant matrix. Wandering Jew may occasionally be reduced sufficiently to allow some native seedling survival, but shading alone is unlikely to totally eliminate it. This leaves the opportunity to recover and thrive wherever available light allows. Wandering Jew can be controlled both by hand weeding and herbicide spraying, but both approaches require persistence. Because of the effort required, hand weeding is only practical on a small scale. The intertwined mat of stems can be rolled up, removing a very large proportion of the plant mass. This is usually collected in bags to be composted, covered where it lies on the site with black plastic or buried. Hand weeding has the least impact on native seedlings, so is a good option where the infestation is small and native regeneration is already healthy. But most restoration sites are too large for manual control alone and spraying is the only practical alternative. Triclopyrâ€“based herbicides are generally considered the most effective when applied at the manufacturerâ€™s recommended rate. A suitable wetting agent and a marker dye is commonly used in conjunction with this herbicide. Several wellâ€“timed applications will be necessary to achieve control. Sometimes the addition of glyphosate to control grasses is helpful for the first application. After this, a regular programme of spraying will be required as soon as new leaves appear on the stems. Spraying may continue every two or three months for two years or more, but after the first year, only occasional live stems or patches
Wandering Jew: An attractive house plant but serious threat to biodiversity.
Wandering Jew: This example of the weed even reached and persists ten metres up this bridge.
Wandering Jew: Here, it hitches a ride down river in a flood. 83
THE FOREST FOR THE TREES will persist and although spraying will require persistence, concentration and thoroughness, only small amounts of triclopyr need to be applied. Woolly nightshade (Solanum mauritianum) Naturalised since 1883, woolly nightshade has in recent years become a significant pest plant in pasture and unmanaged areas. Rapid growth and early and prolific seeding make it a serious invader there. Only partially tolerant of Wandering Jew: In this example, it covers the shade, this incredibly quick growing small tree ground and smothers any seedlings trying to is not much of a threat to regenerating native grow up through it. forests unless it forms dense thickets. In that case, woolly nightshade has been shown to have allelopathic effects; that is, the inhibition of the germination of seeds of other species in the soil beneath it. Control: Occasional woolly nightshade can be cut and the stumps poisoned. Yellow flag iris (Iris pseudacorus) This plant was introduced as an ornamental aquatic plant, but by 1938 it had naturalised. Its leaves grow to about 800mm tall, so it is not a particular threat to most native shrubs, but in pasture it completely takes over. Rumour has it that plants established to beautify Lake Rotoroa (Hamilton Lake Wolly nightshade lacewing. Here the lacewing tends to its young. Domain) are the source of all the plants along the Waikato River downstream from Hamilton. Because the site of the Waioteatua Stream project is largely wooded already and yellow flag is not particularly tolerant of shade, this species is not widespread. In open areas, however, it does exist and so will remain a source of reâ€“infestation elsewhere along the river if it is not controlled. Control: Yellow flag iris can be easily controlled by spraying with metsulfuronâ€“ methyl. Repeat applications will be necessary to control regrowth from the rhyzomes and freshly germinating seedlings.
Woolly nightshade: solanum mautitianum. 84
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Yellow flag iris: The weed is taking over in this part of the Opuatia Wetland.
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Bracken fern: Growing beside weeds like blackberry and bindweed.
Bracken ferns: New fronds unfurl.
Cabbage tree: A closeâ€“up of one of the profusion of flower spikes .
Cabbage tree: Typical cabbage tree habitat in the river flood zone.
Cabbage tree: The fruit ripens to this creamy white or sometimes blue colour during February.
Cabbage tree: Some years the cabbage trees put spectacular effort into their flowering. 86
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Native species It’s a jungle out there
his chapter covers native plant species specified for the recreating of a native plant community at the Waioteatua Stream, Lake Maratoto, Te Aroha Domain, Ngaroto and Mangarata Stream projects. While Charles Darwin referred to the “struggle for life”, the environmentalist Tim Flannery compared interspecific competition with an arms race. The character of these plants has been moulded by their physical environment and their interactions with the species around them. This has shaped them into a community of species which fits together like a jigsaw puzzle. The descriptions of the plants found in, and intended to be returned to these projects, focus on the strategies, tolerances and vulnerabilities of each. Their physical appearance is revealed in the accompanying photographs. A list of useful guides for the identification of native plants is found in the bibliography. This section is not intended to be a comprehensive list of suitable plants for restoration projects throughout the country. It is intended to illustrate the kind of information about various plant species to be gleaned from careful observation of reference ecosystems on similar land environments to an intended project site.
in the early stages of a project that begins on bare land. Eventually, they will diminish to persist in only small numbers around the margins and disturbed areas, where their function is still important. Bracken fern/rarauhe (Pteridium esculentum) Colonisers may both facilitate succession to a more durable plant community by providing shelter and slow it down by shading out mid–species and successional ones. At the Maratoto site, bracken appears to compromise rather than contribute to the maturation of the native plant community. Where bracken grows around Lake Maratoto, the upright fronds emerging from underground rhizomes can reach well over 1m high, so are a significant threat to young seedlings, at least for the first year or two. Once a canopy of taller vegetation establishes, it ceases to be a problem. This species is also found in South America, Southeast Asia, the Pacific and Australia, and closely–related bracken ferns are found throughout the world.
Cabbage tree/ti kouka (Cordyline australis) After karamu, cabbage trees must be a very important component of any restored forest. This landmark of the rural landscape is a Colonisers prolific disperser, producing large quantities Each category of plants has a specific of white to blue berries, filled with small black function. The colonisers will be quick to seeds that quickly germinate. And the young establish, suppress or out–compete weeds seedlings are quick to establish and tolerate and provide shelter for other groups of plants. almost any position, so long as the sunshine Colonisers will be the most common plants is ample. 87
THE FOREST FOR THE TREES Unlike karamu, the single, upright stem continues to grow well despite soft wood. Eventually, the leaf–cladded, juvenile single leader branches and the characteristic tufted form emerge. Although not typically a forest tree, the cabbage tree will persist, surviving flooding and permanently waterlogged roots well, until contemporaries eventually catch up and shade deprives it of the energy needed for survival. Although it thrives in flood–prone sites, the leaves of the cabbage tree are quick to Kanuka: These natives can dominate a forest for surrender to flooding, so the height of the last the first 100 years. flood is often betrayed by the level of the local cabbage tree leaves.
Kanuka: The trunk of a 50–year–old kanuka.
Kanuka: These capsules ripen and release millions of seed on every tree in early autumn. 88
Kanuka (Kunzea robusta) Although it can form a forest on its own, kanuka is usually a tree found in successional forest and shrubland, so it might be placed either with colonisers or canopy trees. Given ideal growing conditions, kanuka commonly grows to 20m or taller and will persist for more than a century if taller trees do not overtake it. These features qualify kanuka as a canopy tree but its abundance of tiny wind dispersed seed, its astonishing growth rate once seedlings are established and its intolerance of shade ensures that kanuka more commonly sits with colonisers. On the case studies covered here, kanuka is the ideal coloniser where a tall, persistent forest is a priority and there is no haste to progress to canopy dominance by later successional species. In parts of the country, in fact, kanuka is the dominant colonising shrub. Its persistence ensures that the plant community that establishes under it will be very different to that which establishes under karamu. Karamu fails after a few years, quickly giving way to longer–lived shrubs like mahoe (Melicytus ramiflorus), mapou (Myrsine australis) and the small–leaved coprosmas if they are present on the site, and to weedy exotics if these native shrubs are not waiting
THE FOREST FOR THE TREES in the wings. Kanuka, on the other hand, continues to provide shelter and deter weeds for much longer, allowing time for a rich diversity of native plants to establish. Karamu (Coprosma robusta) Karamu must be the most important species in many riparian restoration projects. Not only does it grow quicker, shading out weeds, than almost any other woody native plant, but its tolerance of winter flooding and waterlogged soils makes it a safe choice for most positions. All these desirable properties might fool us wondering if any other species is really necessary, but it is with good reason we do not only plant karamu: it will begin to fade within a decade. Either the soft wood, so quickly laid down, succumbs to disease, or surrounding shrubs rob it of the sunlight it craves in abundance. By this time, however, it has established a canopy, shading out weeds and sheltering the neighbours. Karamu can safely retreat from its dominant position as the other trees and shrubs expand to fill the gaps. It will always have a place on the margins and will quickly fill any gaps caused by floods, slips and fire. Like all coprosmas, the flowers are wind pollinated, giving way to generous clusters of bright orange drupes between February and June each year. Karamu is an ideal colonising species where succession to a more complex midâ€“ successional canopy is required within 10 to
Kanuka: Flowering results in a dusting of white over the kanuka forest at Christmas.
Karamu: Such a quick grower and so easy to establish, it dominates projects in the early years.
Karamu: A closeâ€“up of the leaves and fruit of karamu.
Karamu: The male flowers have long stamens designed to move and shed their pollen when the wind is blowing. 89
THE FOREST FOR THE TREES 15 years. Mahoe (Melicytus ramiflorus subsp. ramiflorus) Placement of plants in specific categories can be a bit arbitrary. Some, like pukatea (Laurelia novae–zelandiae) or titoki (Alectryon excelsus subsp. excelsus) clearly fit the tree category. Karamu is one of those clear colonisers and does not fit well into any other category. Mahoe, on the other hand, is not so clear cut. It grows quickly and disperses very well with vast quantities of fruit attractive to birds, but is also more vulnerable to frost and drought than many colonisers, though it is more tolerant of shade. Where frost is not a consideration, like on the lower slopes of Te Aroha, and with some existing cover, mahoe is best placed with the colonisers. In these situations, it becomes the ideal plant to establish a canopy that will suppress blackberry and bindweed. Mahoe will persist well after the karamu have failed and expand into the gaps as this happens. Mahoe is already common on the Waioteatua Stream and Te Aroha Domain sites and will tolerate the long–term flooding experienced on the Waikato River. But the frosts at Lake Maratoto will preclude its planting there until protecting vegetation is established, something that also suppresses grass and other herbaceous weeds that seriously affect mahoe. Slugs prevalent in the grass attack the soft bark and any new growth shoots and mahoe really struggles to survive in dense grass.
Mahoe: Ageing mahoe on farmland.
Mahoe: Flowers and fruit emerge all along the branches.
Manuka (Leptospermum scoparium agg.) The narrow–leaved race of manuka found in the lower Waikato River valley is probably better treated as a distinct species. Unlike manuka elsewhere, it occurs in wetlands and seldom on other landforms. Prolific seed production and vigorous growth even in infertile soils often results in almost pure stands of the shrub. These stands can grow up to 8m or more at times, but stem–boring insects and shallow
Mahoe: Typical of colonising species, mahoe produces masses of seed. 90
THE FOREST FOR THE TREES roots in soft ground often limit its life span, ensuring the succession to a more durable plant community if suitable species are nearby or, in their absence, to a combination of exotic vines. Because in this area manuka is predominantly a wetland species, it is a suitable coloniser on sites destined to become swamp forest, but not as suitable on drier ground, where kanuka, karamu and mahoe will do well. On very wet and infertile sites, manuka may never be succeeded by taller trees and shrubs. Instead, a swamp community consisting of manuka, New Zealand flax/harakeke, cabbage tree/ti kouka sedges and an occasional
Manuka: A typical swamp manuka habitat along with flax, hukihuki cabbage tree and karamu.
Manuka: Wetland manuka in the Waikato have these bright red aerial breathing roots.
Manuka: Flowering in October.
THE FOREST FOR THE TREES stunted kahikatea develops
Although not the most significant category of plant in the early stages of a project, these trees will eventually grow to dominate a site. Each small seedling will have an influence far greater than other plants, but only once the forest begins to mature. Until this happens, the trees may well be slower than other species and have sparser foliage, but eventually their time will come. Some trees, like kahikatea or matai (Prumnopitys taxifolia), will survive in very exposed sites and will benefit from ample Houhere/lacebark: This is a small tree which sunlight available with early planting. Others, grows quickly along stream banks where like tawa (Beilschmiedia tawa), pukatea flooding causes constant disturbance. (Laurelia novaeâ€“zelandiae) or titoki (Alectryon excelsus subsp. excelsus) require shelter from hot sun, frost and wind and are more tolerant of shade. These may be better reserved for supplementary planting in subsequent years. Houhere/lacebark (Hoheria sextylosa) The growth strategy of lacebark is very similar to its cousin manatu. Lacebark, too, is a common small tree along stream sides, especially those exposed to flooding and erosion, but it is not so common in mature forest. Although lacebark copes well with dramatic Houhere/lacebark: Flowers in the autumn. flood events along streams and grows well in the damp soil often found at the foot of hillslopes, the long periods of flood inundation along the lower sections of a large river like the Waikato may be too much for its roots to tolerate. Kahikatea (Dacrycarpus dacrydioides) Kahikatea trees are quick to establish after a flood, fire or any disturbance, yet they grow to be our tallest tree, some nearly 60m high. Because they tolerate wet soil and the seedlings can remain underwater for months during winter, they were once the most prolific Houhere/lacebark: The seeds appear about a tree along our rivers and wherever soil is moist month after the flowers are open. or poorly drained. Kahikatea will grow on 92
THE FOREST FOR THE TREES hillsides as well, but seldom establish under a forest canopy unless a catastrophe creates the ideal open space. When this happens, they can grow quickly and have a good chance to win the race to claim their place in the sun. Seedling kahikatea can be vulnerable to drought in their early years and even older trees can succumb to a dry season or a permanent change in the wetness of the soil. Like so many of our native conifers, male and female cones are found on separate trees, ensuring crosspollination every time. The female cones have a bright orange, sweet, fleshy base which attracts birds that aid dispersal. From the base of the trunk, shallow roots run over the moist ground, ensuring a wide base to support the height and aeration for the roots. Kahikatea: In good years the fleshy bird attracting cones give the trees a red glow.
Kahikatea: Typical podocarp cones with one, occasionally two seeds attached to the bright fleshy base.
Kahikatea: Our tallest tree stands out above the canopy.
Kohekohe (Dysoxylum spectabile) Kohekohe is a modest tree that can contribute to the canopy of forests under 15m high. Because kohekohe is vulnerable to frosts, it is found mostly in the north of the country Kohekohe: In pasture on the slopes of Pirongia. 93
THE FOREST FOR THE TREES or along the North Island’s coast. The well–drained lower slopes of Mount Te Aroha provide ideal habitat for such an attractive tree, which in turn, provides fruit to attract tui and other native birds during the winter, when food is not so plentiful. Occasional kohekohe are also found along the Waikato River, where such a large body of water reduces the effect of frost and the remaining vegetation protects seedlings from the desiccating effects of summer sun.
Kohekohe: Flowers appear during winter and produce fruit the folowing winter .
Kowhai (Sophora microphylla) To assemble a plant community with the collective capacity to out–compete invasive exotic weeds, we need trees that grow quickly and tall, have dense foliage and preferably grow well even in dense shade. Kowhai has none of these qualities, but it does tolerate waterlogging, flooding and frosts. Its other redeeming feature is the profusion of nectar–rich flowers it tempts the Kowhai: Growing in full sunlight, kowhai produce birds with each spring. a profusion of flower, dripping with nectar. On these sites discussed in this section, kowhai will only grow well along the edges, where it will never be shaded out by taller or faster–growing trees. Matai (Prumnopitys taxifolia) Another of our native conifers, matai frequents alluvial terraces and swampy places in contrast to its close relative, miro, which is more at home on hill slopes. Matai is one of our hardiest trees, tolerating both flooding and drought. Possibly because the juvenile phase is almost leafless, matai even tolerates spray drift from well– intentioned herbicide better than almost any other native tree, so although it grows slower than kahikatea, it is a good tree to introduce into a difficult habitat. Because, like many other native conifers, matai is dioecious — having separate male and female trees — and land clearance has fragmented local populations, replacing this species in restoration sites may be crucial for its continued widespread survival.
Kowhai: The seed pods will persist on the tree for months but do have enough surface area to be carried quite a way by the wind .
Kowhai: The hard seed coat protects the seed and allows it to float on water for years and travel long distances before germinating . 94
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Matai: This species have a very distinctive hammered appearance to the bark.
Matai: Occasional matai are found amongst kahikatea on low lying ground.
Matai: The pollen bearing cones appear on male trees in the spring.
Matai: The matai seeds are enclosed in this sticky , fleshy drup like cone.
Matai: Unlike some trees, matai seedlings will continue to grow in a shady forest. 95
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Pokaka (Elaeocarpus hookerianus) Shade tolerance is often closely associated with vulnerability to frost. This makes sense, because shady places are usually also sheltered from frost. Pokaka, though, is an exception to this rule, being very tolerant of frost as well as flooding and shade. These qualities make it an important component of the project, but are not the only reasons pokaka is included. Among the small remnants of forest dotted across the landscape, we find the occasional pokaka and several others isolated from it by farmland. If pokaka is to persist, it must be replanted in the gaps between these remnant trees to restore one large population rather
Pokaka: Elaeocarpus hookerianus.
Pokaka: A close–up of the fruit and leaves (left). Pokaka seedlings (right) look nothing like the adults.
Pokaka: Occasional pokaka are found growing in kahikatea remnants.
than several isolated fragments. Pukatea (Laurelia novae–zelandiae) Pukatea grow in similar damp soil to kahikatea and also tolerate seasonal flooding, though not as well as kahikatea. Pukatea seedlings thrive in the shade of other trees, which is fortunate, because they are not very tolerant of frost or cold wind. As a forest matures, pukatea may become more prevalent. Pukatea’s pale trunks are supported at the base by large spreading buttresses, a real benefit in soft wet ground. Pukatea flowers are tiny and inconspicuous, the pear–shaped capsules dry out and split Pukatea: A typical site for a pukatea on open in autumn, to release fluffy coated seeds farmland with ample water on the roots. which must at times be carried considerable 96
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Pukatea: Inconspicuous pukatea flowers in spring.
Pukatea: The pale trunk is often host to mosses. The buttressed roots help with stability in soft damp soil which pukatea grows so well in. distances on the wind. Puriri (Vitex lucens) Puriri is another, mostly coastal species found on the lower slopes of Te Aroha. Although puriri seldom exceeds 20m in height, the trunk can be several metres in diameter and the branches wide spreading. Puriri will grow on poorlyâ€“drained ground as well as it does on the sloping site at Te Aroha, but when found inland, prefers growing on hillsides, where frosty air can drain away. This species is restricted to the coast of the northern half of the North Island and inland
Pukatea: In late warm summer and autumn days the capsules split open and release the feathery seeds to the wind.
Puriri: These thrive in frostâ€“free sites, along the Waikato River, on hillsides above the basin and along the coast.
Puriri: Its flowers and fruit can be found almost year round. 97
THE FOREST FOR THE TREES along the lower Waikato riverbanks. Rewarewa (Knightia excelsa) Sometimes called New Zealand honeysuckle because of the profusion of nectar produced by the flowers in early spring, rewarewa is an important food source which in modern times draws tui back to forested areas in time to nest. Rewarewa grows quickly and soon becomes the dominant tree in young, regenerating Rewarewa: Capsules dry out and split to release the winged seeds in autumn. Rewarewa: Knightia excelsa or rewarewa is a tree of young regenerating forest, particularly on hillslopes.
Rewarewa: The spectatular flowers attract flocks of nectar eating birds in October.
Rewarewa: Some years the trees are covered in flower. forest. Ribbonwood/manatu (Plagianthus regius subsp. regius) Manatu is a quickâ€“growing tree, usually found on alluvial terraces. Because it is so much taller than the seedlings of other species, it has good access to sunlight, so it can also be found in young, regenerating forest. Not only is this tree very tolerant of occasional flooding, but it also tolerates permanently waterlogged soils, making it an ideal early component of any riparian forest community. Manatu is deciduous in southern climates, its winter leaf depletion increasing with latitude. The growth form also varies across the range, with a more divaricate juvenile in southern latitudes. Each seed is encased in a small, dry, extremely Ribbonwood: Young ribbonwood planted out on the riverbank. buoyant capsule, so manatu seeds will float well and be deposited wherever floods can 98
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Ribbonwood: Male flowers in the spring (left) while clusters of seed capsules (right) clothe the ground below ribbonwood in late summer.
Ribbonwood: A carpet of ribbonwood seedlings sometimes appear after a good seeding season. carry them. Sometimes there is a high mortality rate among seedlings planted in tall grass; this may be due to slugs in the grass damaging the thin, soft bark. Swamp maire/maire tawake/waiwaka (Syzygium maire) Suitable habitat for this rather attractive tree is scarce in the Waikato region. Swamp maire has breathing roots, called pneumatophores, that allow it to thrive on soil that is waterlogged Swamp maire: They thrive in wet places where all year round. It does not tolerate drying out. few other trees will grow. The seedlings are very intolerant of frost, Swamp maire: The which frequently precludes it being planted in fruit containing a frostâ€“prone, lowâ€“lying areas or before suitable single seed appear frost protecting cover has established. In the almost a year after Waikato lowlands, swamp maire now persists flowering. mainly in small, isolated groups, often as remnants on suitably swampy forest remnant
Swamp maire: Typical myrtle family flowers in March.
Swamp maire: Take real care when walking under swamp maire to avoid damaging these breathing roots.
THE FOREST FOR THE TREES habitat on farmland. Titoki (Alectryon excelsus subsp. excelsus) Titoki is fussy about its habitat: it doesn’t want to be too wet or too dry, it doesn’t want too much sun, too much frost or too much wind, and, as if that wasn’t enough, it is slower–growing than some other trees. All this might make us wonder how it has survived past millennia, but survive it has. Titoki will continue to grow in shady places and tolerate the dry if the sun is kept at bay. Perhaps the slower growth is the secret to the hard wood which must contribute to its Titoki: This example of the species was planted survival. Quick growing trees are an essential more than 30 years ago. element of a plant community but the slow Titoki: The seeds (left) growing resilient species like titoki contribute partly enclosed in Titoki: A distinctive incised trunk is a these bright red fleshy feature of the titoki. fruit appear in spring a year after flowers. Titoki: The tiny flowers (right) are either hermaphrodite or male. They appear in spring .
Totora: Suited to riparian margins. Totara: The sweet fruit have one or sometimes two seeds attached .
a permanence otherwise missing. Totara (Podocarpus totara var. totara) Tolerant of both dry and wet soils and prolonged winter flooding, totara is ideally suited to riparian margins, particularly higher ground prone to drying in summer. The pungent leaf tips make it unattractive to cattle and this feature is reputed to be the reason it is more common in some parts of the country than ever before. The way totara has thrived on the seasonally waterlogged peat soil at Lake Maratoto is testament to its persistence. Seedlings, however, while tolerant of winter flooding, are vulnerable to floods while actively growing in
THE FOREST FOR THE TREES Coprosma areolata growing in open pasture.
Understorey Most colonisers are not fussy about their habitat, as long as they get enough sunlight. Trees are more particular, but even they are not as fussy as the understorey shrubs. Sunlight is the source of energy for almost all plants and the most sought–after resource vigorously competed for by all with green leaves. The understorey shrubs, however, sacrifice access to the brightest sunlight. This they leave to the colonisers and trees, but they pay a price. Because they forfeit sunlight, understorey shrubs cannot afford to contribute resources to developing tolerances to conditions they may never meet. They become specialists in their particular habitat. The shrubs included here are not a representative sample of forest understorey but those particularly well adapted to these sites. Even these, though, vary considerably in what they tolerate and what they are vulnerable to, so particular care must be taken to place them appropriately. Sites that already have significant canopy cover will support a range of understorey shrubs that might otherwise be too vulnerable to frosts in winter, hot sun in summer or rampant weeds. Coprosma areolata, C.rhamnoides These two, small–leaved, divaricate shrubs are common in the understorey surrounding the Te Aroha site. In this region, there are a number of closely related, small–leaved coprosmas, each occupying a slightly different habitat. Coprosma tenuicaulis and C. propinqua grow in very wet swampy places, C.rigida and C.rotundifolia are found on slightly drier places particularly if they are subject to occasional flooding. Coprosma areolata grows in a wide range of conditions, especially if, for some reason, related and competing coprosmas are absent. Where they are to be planted on the Te Aroha site, C.areolata and C.rhamnoides grow
Closeup of the leaves with the distinctive pointed tip and obvious veins(right).
The blue black fruit appear mid– summer. Typical Coprosma rhamnoides habitat, dry clay hillside under kanuka.
Tiny ruby coloured fruit on Coprosma Rhamnoides (right).
THE FOREST FOR THE TREES Coprosma propinqua and its hybrid with karamu a useful understorey plant in damp forest.
well together on steep ground with shallow soil, both in exposed sunny places and in deep shade. Coprosma X cunninghamii/Coprosma propinqua X C.robusta This naturallyâ€“occurring hybrid is one of the best native plant survivors along the river flood zone. A cross between C.propinqua and karamu (Coprosma robusta), this hybrid and the back crosses, grows more quickly than C.propinqua, tolerates shade and flooding better than either parent and tolerates frost better than C.robusta. C X. cunninghamii will be planted in the lower flood zone, after winter flooding where it is expected to be the best adapted plant to these challenging conditions. This will also be the most numerous and most useful understorey plant in the Maratoto project.
This grand old Coprosma rigida was growing on a farm stream bank.
The orange fruit confirm it is Coprosma rigida. This scan (left) gives a clearer view of leaves and fruit.
Coprosma rigida Coprosma rigida often grows alongside Coprosma rotundifolia in similar conditions and also tolerates both waterlogged soil and flooding. Where C.rotundifolia is generally a large shrub, often with many stems, C. rigida frequently develops into a small tree with a single trunk and more upright form. Both of these species will also grow on wellâ€“drained sites. Coprosma rigida looks similar to the swamp coprosma/hukihuki (Coprosma tenuicaulis), which has similar leaves but more slender stems. Hukihuki is a true swamp plant, frequently growing in shallow water, but there is some overlap in habitat. The orange fruit of C.rigida and the red to black fruit of hukihuki in autumn is the most obvious difference. Both of these coprosma species are now uncommon along the river and on wetland margins because of clearing for farmland and establishment of competing weeds. There are isolated individual plants which set little or no fruit as a result of their isolation. The restoration of these species along the river will help ensure the survival of any
THE FOREST FOR THE TREES Coprosma rotundifolia growing in a Waipa valley backswamp.
locally distinctive genes and help create a more resilient plant community. They are an important part of the character of the landscape. Coprosma rotundifolia Coprosma rotundifolia grows particularly well along stream, river and wetland margins where waterlogged soil or persistent flooding restricts the competition for sunlight. Along the Waikato River, it can be submerged for several months during winter, then have all of the leaves covered in fine silt when the water subsides. New leaves emerge soon after, with the shrub none the worse for the experience. Summer flooding, however, will wash away any developing fruit. Coprosma rotundifolia is dioecious—it has separate male and female individuals—so it is important to plant sufficient to ensure pollination if succession is intended.
Coprosma rotundifolia close–up of the leaves and fruit in January (right). The distinctive bilobed fruits of Coprosma rotundifolia.
Hangehange (Geniostoma ligustrifolium var. ligustrifolium) Hangehange is one of our most common native shrubs in the North Island, thriving in exposed coastal conditions, in swamp forest and on steep, well–drained banks. It will be a significant contributor to the plant community at Te Aroha, but will be used Hangehange can be found on most soil types. sparingly on the other two sites, where it may The capsules (right) dry out and split open to reveal clusters of tiny yellow seeds. be vulnerable to frost and flooding. The flowers of Heketara (Olearia rani) hangehange are obvious Heketara is a shrub quite similar in in this picture but not so appearance and habit to its relative, rangiora. obvious from a distance. Heketara is quite fussy about having well drained soil, but it is perhaps a little more tolerant of dry, infertile or shallow soil. This Well–drained soil which makes it a valuable component of the Te never dries out and plenty Heketara leaves and of sunshine suit heketara flowers. There is a mass best. of tiny white hairs on the underside of the leaves turning them white.
THE FOREST FOR THE TREES Aroha plant community. Like rangiora, there is a small amount of suitable habitat at the Waioteatua Stream site, and planting a few specimens there will help ensure its survival as well in the vicinity.
A mature specimen of Kaikomako.
In some areas the leaves gradually transition from the juvenile to the larger adult leaves. Here the transition is abrupt. Seedlings have tiny leaves and divaracate branches.
Some years kaikomako produce large clusters of shiny black fruit.
Coprosma grandifolia female with fruit on the left and a male in flower on the right.
Kanono flowers are typical of this group. These female flowers have magnificent stigmas and an insignificent corolla.
Kaikomako (Penantia corymbosa) Kaikomako is a shrub or small tree well suited to swampy soils, although it will also grow on hillsides. Its shade tolerance is not as developed as some other understorey shrubs, so it is more commonly found along forest margins and where the canopy is more open, often due to poor soil conditions. Although kaikomako is a shrub of boggy places, it is not commonly found where flooding is likely to leave it completely submerged for long periods. Being slow growing, kaikomako produces durable wood, allowing it to survive to a respectable age. Kanono/karawiki (Coprosma grandifolia) Kanono is a shrub of damp shady lowland forest, not specifically of riparian margins or wetlands, but it tolerates flooding and moist soils well. Kanono is vulnerable to frosts and drought, so for the Waioteatua project, it will be placed in shallow depressions where soil remains moist, and with cover to protect it from the light frosts that might occur along such a large body of water. Kanono produces large amounts of bright red succulent fruits in late summer. These not only help support the resident native birds, but lure them from the hills to the site, where they might bring seed to augment The male flowers are also typical with stamens which move and shed pollen in the wind.
THE FOREST FOR THE TREES the project. Kawakawa Kawakawa (Piper excelsum) thrives in Kawakawa has an interesting combination the deepest of qualities. shade. Like colonising plants, kawakawa grows very quickly so that it can be the first understorey plant to establish in shady places cleared by flooding or grazing. Its wood is soft and vulnerable to disease so, like many colonisers, it is frequently short lived. But because kawakawa is very vulnerable to frost, grows in particularly shady places and allows very little sunlight to pass to the ground below, it fits more comfortably into the understorey category. Kawakawa fruit appear early December (left) Kawakawa will not tolerate even very brief while the male flowers start shedding pollen in flooding events, so it is commonly found on August (right). steeper ground where flooding is unlikely Kotukutuku grow along or at least infrequent enough to allow it to streamsides but above establish, thrive and set fruit between flood the flood level (left). events. Some kotukutuku like Copious quantities of seed are produced in this (lower left) have early summer, embedded in succulent fruit. hermaphrodite flowers. This kotukutuku (below) Kotukutuku (Fuchsia excorticata) is functionally exclusively Kotukutuku is the world’s tallest fuchsia female. some grow as tall as 14m—and does best in damp, shady, sheltered places, though it doesn’t tolerate flooding over its roots. The flowers, which may be either female or hermaphrodite, first appear in November, and the first fruits are available to birds while other flowers are still opening. This valuable resource happens to coincide well with nesting time for native birds and the blue pollen spread around their faces betrays where they have Cyathea been dining. medularis Kotukutuku leaves and any soft new growth mamaku. are vulnerable to frost, but the wood survives well and new shoots appear in the spring. Mamaku (Cyathea medullaris) Mamaku, like all ferns, disperses well, producing large quantities of tiny spores that can be blown long distances on the wind. But once the spores reach a new site, they require a consistently damp shady place to resume 105
THE FOREST FOR THE TREES Mapou is common along roadsides, in forest understorey and even in swamp forest.
the multifaceted fern life cycle. Mamaku produces a tight mass of roots, not only surrounding the trunk, but also throughout the surrounding ground. This mass of roots does a remarkable job of stabilising the ground and resisting erosion. We can be confident that mamaku will eventually establish on all of the case study sites, but there is merit in speeding up the process by planting a few.
Mapou (Myrsine australis) Mapou, sometimes called red matipo, is so widespread because it has such a wide range of tolerances. Mapou will grow in a wetland and on steep dry slopes. It will grow in harsh sunlight and in deep shade. Light frosts have little effect, but heavy frosts will cut young growth. Mapou produces hard, durable woody trunks and can live to a good age. Suckers grow from the roots, sometimes resulting in a colony of plants (ramets) all connected underground. The tiny flowers can appear in dense clusters at any time of the year and lead to small purple Mapou fruit takes a year to develop and ripen. drupes a year later. The shrub has a break before flowering again. These are a favourite of fruitâ€“eating birds Fruit can be found at any time of year. and a good reason for its inclusion in these projects. Mingimingi has the Mapou is a slow grower, so should be planted resources to thrive on in a stable environment and some shade to infertile soil in wetlands deter weed competition is a help. and dry banks.
The small flowers grow in clusters at any time of the year.
The minute drupes of mingimingi (left) turn crimson around Christmas. You have to look closely to spot mingimingiâ€™s tiny delicate flowers in spring.
Mingimingi (Leucopogon fasciculatus) Mingimingi is one of few native plants persisting at Lake Maratoto. Found equally on infertile clay banks, adjacent to salt marsh and on drained peat, this shrub is evidently persistent where other species fail to thrive. Seedlings are beginning to appear under the older plants at Lake Maratoto. Mingimingi is difficult to cultivate, so it is not often planted in restoration projects, but its prevalence at Maratoto ensures it will be included in the small number of trial plants included in the design.
THE FOREST FOR THE TREES Leaflets on some juvenile pate plants are deeply incised. This doesn’t persist on the adults.
Pate (Schefflera digitata) Like kotukutuku (Fuchsia excorticate), pate, sometimes called patete, is typical of damp, shady places. The large, rather thin leaves are quite prone to wilting if the ground gets too dry, but will also wilt quickly if the roots are flooded, so pate is found in the damp soil of gullies, but only above normal flood levels. Given these ideal conditions, pate thrives and can dominate the understorey. The Te Aroha site, being sheltered from wind and frost, well above floods but having permanently moist seeps, provides such a habitat. Pate, in turn, produces copious amounts of small succulent fruit in late autumn and winter, when it is most welcome to many native birds. Putaputaweta (Carpodetus serratus) It seems ironic that many of our stream side shrubs and small trees, though in need of damp ground, are so vulnerable to flooding. This is the case with a number of species, including putaputaweta, a common small tree found in damp areas where there is, opportunely, little risk of flooding. Putaputaweta is one of the first stream–side trees to show signs of stress in dry conditions, but also one of the first to wilt when floodwaters exclude air from around the roots. These trees can be found covered in a profusion of tiny white flowers in the spring, when the fruit from last year’s flowers still have six months to ripen. By the time they do, the next year’s crop will be half grown. Putaputaweta will be planted at the Waioteatua Stream site around the wetland area, above the annual flood level. Rangiora (Brachyglottis repanda) Rangiora will be a common understorey shrub on the Te Aroha project. Like heketara (Olearia rani), it is fussy about soil conditions, requiring well–drained, preferably sloping ground doesn’t dry out. Under these conditions, rangiora thrives and grows very quickly, eventually to a height of about 7m.
Pate fruit is ripe mid–winter (left). Pate will grow along forest streams but does best on forest margins.
Putaputaweta , an understorey tree of damp forest. Its fruit ripens 15 months after flowering.
A bit fussy about ground conditions, rangiora likes soil to be well drained but not too dry. The mass of tiny hairs on the underside of rangiora’s leaves turns the underside distinctively white.
THE FOREST FOR THE TREES There is a small amount of suitable habitat at the Waioteatua Stream site, and planting a few specimens there will help ensure its survival in the vicinity.
Coprosma lucida or shining karamu with fruit. Left, a closeâ€“up of the fruit and leaves.
Shining karamu (Coprosma lucida) This largeâ€“leaved shrub has bright, glossy green leaves and clusters of orange fruit in the late summer and autumn, just like its close relatives, karamu and kanono. But unlike karamu, this one tolerates the shade of a forest and unlike kanono, it will grow well in quite dry, steep places like those found on the lower slopes of Te Aroha.
Swamp mahoe (Melicytus micranthus) Melicytus micranthus is another of the Melicytus micranthus means shrubs characteristic of the banks of the small flowers. Their drupes lower Waikato River and other waterways (below) are small too. vulnerable to persistent flooding. Sometimes called swamp mahoe, this relative of the mahoe (Melicytus ramiflorus) is more likely to be found in places which vary through the year, from dry in the summer to several metres deep in muddy water during winter. Turepo thrives in deep Melicytus micranthus is slow growing, forest but it is easier to intolerant of intense sunlight in summer get a picture here in the and difficult to establish, but is an important open. component of the riverbank life, tolerates flooding and shade well and, once established, is long lived.
Female turepo flowers (top) and male flowers (above). Streblus fruit are never abundant (right).
Turepo (Streblus heterophyllus) Slowâ€“growing, sparse foliage and shy fruiting, this species is not used as often as it could be in riparian restoration projects. Because when the conditions are right, this small tree thrives. Although turepo can be found on forested hillsides, it is on alluvial terraces and the margins of wetlands where it comes into its own. Turepo will continue to grow well in the shade of taller trees, copes well with waterlogged soil and is equipped to survive long periods of flooding completely submerged, when most other shrubs would die. Struggling to survive exposed grassy sites, once taller cover is established, turepo is one 108
THE FOREST FOR THE TREES of the most successful survivors.
Climbers and epiphytes
Climbers and epiphytes neither grow tall, self–supporting structures to access sunlight, nor accept remnants of light filtering through the leaves above. This group of native plants instead takes advantage of the support of surrounding trees to provide access to full sunlight, and in so doing has been more successful than any other in its attempt to survive the onslaught This photo of hound’s tongue fern shows the distinctive fleshy rhyzome with black scale scars of exotic imports. as well as the sori. Parsonsia heterophylla Karamu Bush. These produce quite spectacular flowers (below left). The juvenile leaves are quite different from those on mature vines (below right).
Hound’s tongue fern/kowaowao (Microsorum pustulatum) Lush growth of hound’s tongue fern persists on the willow branches along the river and in the forest surrounding the Te Aroha project. With the ability to thrive despite the dominance of willows, honeysuckle (Lonicera japonica) and wandering Jew, this is one of the last native plants to disappear from a site. Hopefully, by retaining the willows on which it grows until a native canopy is established, the future place of hound’s tongue fern will be assured well into the future. Kaihua (Parsonsia heterophylla) Kaihua thrives on the higher ground at the Waioteatua site, where it already scrambles up through the existing mahoe and alders to get full benefit from the sunlight. Kaihua is one of the few native plants still persisting on the site. Kaihua is common on alluvial terraces as well as swampy river and
The parsonsia heterophylla kaihua seed (right).
After the flowers come the seed pods (above left) which split open to release wind dispersed seeds. Mature foliage flowers and a green seed pod (right).
THE FOREST FOR THE TREES Supplejack will climb up and over almost anything making the bush hard to penetrate.
Occasionally, you can find a profusion on kareao.
Kareao/supplejack (Ripogonum scandens) Kareao also persists on both the Te Aroha and the Waioteatua sites. This species is no longer common along the river. Those found there are on higher ground so there is no clear indication of just how much flooding it will tolerate. Planting other specimens in the area may in time provide clearer evidence of where it will grow and where it will not. Kiekie (Freycinetia banksii) Kiekie must be one of the most common native plants in damp lowland forest and tolerates flooding well. It grows so thickly in the forest of the lowâ€“lying islands in the river delta that it is difficult to move around. The river seldom floods these islands because they are so close to the open sea. Kiekie also grows close to the streams flowing off the local ranges, but flooding on these, although quite severe, doesnâ€™t last long. Planting kiekie close to the Waikato River, which floods for several months during some winters, will provide a better understanding of the flood conditions that kiekie tolerates than is available at present. On the Te Aroha site, kiekie will provide a
Kiekie (above) prefer to scramble up tree trunks in damp shady forest. Sometimes the kiekie gets so carried away it is hard to see the tree it is growing on (right).
Both the male and female kiekie plants have these sweet, succulent bracts below the flowers (right). The fruit always in clusters of three contain millions of tiny seeds embedded in the succulent flesh (below right). 110
THE FOREST FOR THE TREES valuable food source for birds. Leather–leaf fern (Pyrrosia eleagnifolia) Possibly our most widespread native plant, leather–leaf fern is common on exotic and native trees in both natural and urban areas. Although in no risk of decline regionally, the Most trees will become adorned with the fleshy retention of willows will ensure the persistence leaves of pyrossia eventually. A close–up of its of this fern on these sites. leaves (right). Pohuehue (Muehlenbeckia australis) Considered by many to be a weed in this situation, this is a very successful native plant. Pohuehue thrives on ground flooded for half of the year and climbs through the willows and alders to form a dense canopy above. There is no need to plant this species and in fact it may be controlled to some extent to allow other plants access to the sunlight.
Pohuehue is a master at growing up over other plants and usurping their sunlight. A close–up of its leaves (right).
Sickle spleenwort / peretao (Asplenium polyodon) Most commonly found as an epiphyte or growing on fallen logs, sickle spleenwort is also a survivor where most other native plants have been lost. Like the other ferns mentioned here, there is no need to reinstate this species as long as the willows and other trees it relies on are retained, until it resumes its natural place on established native trees.
Wetland plants We make a distinction between wetland plants and all of the other forest species because the structure of the wetland is so different from a forest. In the wetland area of these sites, there are no tall trees, so consequently no understorey. Wetland plants are characteristically tolerant of full sunlight and winter frosts. Most tolerate only light shade, but because wetlands tend over time to develop low–nutrient, anoxic, organic soils, many wetland species are adapted to these conditions.
Sickle spleenwort is as much at home on a tree fern trunk as on the ground. The underside of a frond showing the typical spleenwort spore bearing structures (right).
Gahnia/mapere (Gahnia xanthocarpa) Various gahnia grow in a quite a range of Gahnia xanthocarpa growing amongst other habitats, including dry infertile ridges, coastal sedges in a backswamp along the Waipa River. 111
THE FOREST FOR THE TREES The fern Hypolepis distans makes the most of any high ground in a wetland.
cliffs and clay banks. Gahnia xanthocarpa, one of our tallest sedges, grows to more than 3m high in ideal conditions. It is most at home in damp kahikatea forest, but also grows on ground too wet and boggy to support kahikatea trees. Hypolepis distans This fern, not known by any common name, forms tangled mounds on peat soil and sometimes rotting logs. The tangle of fronds is sometimes up to 2m high around Lake Maratoto, where it is occasionally found in association with the more common tangle fern (Gleichenia dicarpa). Trials to transplant underground rhizomes will feature in the Lake Maratoto project as well. Kutakuta (Elaeocharis sphacelata) Another shallow water species and also like Machaerina articulata, Elaeocharis sphacelata thrives in ponds and lakes where the water level is quite stable. This tall sedge is common in Lake Maratoto, but will not find deep enough water in the areas destined to be planted.
Eleochris sphaecelata colonising the margin between wetland and lake at Kainui. These culms (right) have the dual function of supporting reproductive structures and facilitating photosynthesis
Machaerina rubiginosa, M.teretifolia, M.arthrophylla (formerly Baumea species) These sedges with more or less terete (circular in cross section) leaves grow from spreading rhizomes and can cover large areas, particularly M.rubiginosa. Typical habitat is
Above, itâ€™s difficult to distinguish from a distance, Machaerina rubiginosa on the left and M.teretifolia.
Machaerina tenax with these distinctive seed heads (above) prefers more shady conditions Machaerina rubiginosa is distinguished by this unique seed head and the yellow seeds (right).
THE FOREST FOR THE TREES swampy lake and forest margins. These thrive on swampy retired pasture but may recede when shading increases. They are already established at the Lake Maratoto site and will be encouraged. New Zealand flax/harekeke (Phormium tenax) Harakeke thrives in almost any soil conditions, but suffers greatly the effects of shade. For this reason, it is found most commonly on coastal cliffs and very boggy ground, where it gets little competition from taller plants. Because of the tolerance of poor soil, this is a very popular plant for restoring natural areas. Although it thrives almost anywhere, harakeke contributes little to creating a forest environment and quickly fails once one begins to form, so its use should be reserved Harakeke grows anywhere there is ample for those places where it will continue to be sunlight. The harakeke flowers attract birds with competitive. Typically, this means permanent copious amounts of nectar around Christmas. wetlands where it grows in association with swamp coprosmas, cabbage trees and sedges Purei (Carex secta) and Pukio (Carex virgata) Both of these two tussock–forming sedges grow in swamps, sometimes under a light canopy cover. Both will form “trunks” of matted rhizomes, those of Carex secta raising the height to more than 2m; C.virgata, much less. They are easily distinguished by the more pendulous nature of C.secta and the harsher leaves of C.virgata. These sedges are common on both the Waioteatua Stream and Lake Maratoto sites.
The upright spikes distinguish Carex virgata purei (above) from C.secta. Carex virgata seed heads (above right).
Typical Carex secta habitat amongst flaxes in standing water (top) and Inflorescences of Carex secta (below).
THE FOREST FOR THE TREES Swamp blueberry (Dianella haematica) Because of its status as declining, plants of Dianella haematica at Lake Maratoto will be propagated from the site or nearby peatland for reintroduction, rather than risk introducing a similar closely related species. There is only a small extant population on the site and reintroduction of genetic material from elsewhere may be advised in the future, but this would only be done under the guidance of experts.
Coprosma propinqua (right) grow on roadsides and wetlands They just need plenty of sunlight.
The swamp coprosmas: mingimingi (Coprosma propinqua) and hukihuki (C. tenuicaulis) Even in soft, deep mud and shallow water, two woody shrubs persist. Both of these form tangled, divaricate masses: tight, dense masses in full sunlight and a more open structure in light shade. Mingimingi has long, narrow leaves and white to blue to almost black drupes. Hukihuki has almost round leaves and dark red to black fruit. Typical of the coprosmas, both species have separate male and female plants with wind pollinated flowers.
Single white through blue to almost black fruit in leaf axils.
This closeâ€“up shows the foliage and twiggy divaracate branches.
Hukihuki is in its element here growing amongst cabbage trees, flaxes and sedges. This closeâ€“up shows the hukihuki fruit and leaves.
THE FOREST FOR THE TREES
Tangle fern (Gleichenia dicarpa) Gleichenia dicarpa or tangle fern forms dense Widespreading underground rhizomes cover at Lake Maratoto. ensure that tangle fern dominates the ground under mature manuka around Lake Maratoto. In the warm, moist conditions found there, this fern easily exceeds 2m in height and makes getting around very difficult, but it does ensure very little gorse or blackberry establishes in the area. Trials to transplant underground rhizomes will feature in the Lake Maratoto project. Wiwi/ jointed twig rush (Machaerina articulate) Jointed twig rush grows in shallow water where there is little fluctuation in water level throughout the year. Full sunlight is essential and with any variation from these conditions, this spectacular plant fails to thrive. On the Waioteatua project, the river edge is unsuitable because of the extreme fluctuations in water level. In the back swamp, which remains very damp year round and only floods when the river peaks in late winter, this plant is in its element. At Maratoto, wiwi persists in the shallow lake margins and may be planted into any open water in the wetland area.
Machaerina articulata grows well in any permanently shallow water such as here on the shore of Hakanoa (above). The spectacular flower heads in spring result in copious quantities of floating seeds in winter (below).
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Carex dissita, C.solandri, C.lambertiana, C.dipsaceae The damp, sometimes flooded forest floor is ideal habitat for a range of lowâ€“growing sedges. While the taller carices like purei and pukio thrive in very swampy conditions and tolerate only light shade, these shorter sedges are generally found on slightly drier ground, which may well also be shadier. Forest wetland is ideal for the Carex dissita All of the carices will survive occasional (left). Female infloresences along the stem with flooding, but if under water for too long, the the male flowers clustered at the top (right). leaves will rot off, with new growth coming away from the roots as the flood subsides.
Carex solandri spikes (left). The seed bearing culms are so long they are an effective method of dispersing the seed (right).
One of our most common forest sedges, Carex unciniata or hook sedge hitches a ride for its seeds on passing animals.
Hook sedge/kamu (Uncinia uncinata) Another sedge similar to the carices above, but generally restricted to slightly drier ground, is hook sedge, named for the ingenious way each seed has a hook attached to aid dispersal by unsuspecting passing animals. Pratia (Lobelia angulata) The riverbank is a tough environment for any plant because the water level fluctuates so much. The freeâ€“draining soil may be really dry all summer, then under several metres of water for months through the winter. Lobelia angulata grows well on the upper riverbank as long as there is some shade to protect it from the summer sun. The dry periods are hard to tolerate, often causing some leaves and soft stems to wither, but when the rain comes in autumn, this tough little creeper recovers the lost ground. When all else fails, the abundant fruit packed with tiny seeds ensure that a new generation is ready to get going as soon as conditions are favourable.
Lobelia angulata flowers and fruit.
THE FOREST FOR THE TREES Forked sundew (Drosera binata) This insectivorous plant has adapted to the infertile soil found in peat bogs by supplementing its diet with insects collected on the sticky leaves. Increased soil fertility due to farming activities is likely to support the taller, shadier cover which threatens its existence. This drosera will not be planted at the Lake Maratoto site but the exclusion of livestock and a wide forested margin is intended to preserve the lowâ€“nutrient status of the lake and surrounding peat bog. Nertera scapanioides Shallow roots and very low growth habit restrict nertera to specialised habitats. N.scapanioides thrives on peat bogs, particularly in association with sphagnum moss. This habitat provides constant moisture close to the ground surface and refrains from dropping lots of leaves on top of it, as would happen in a lush forest. The lowâ€“nutrient soil seems to be no handicap. As with the drosera, this species is not likely to be propagated, but the project is intended to protect the conditions in which it thrives.
Growing on impoverished peaty soil, drosera (top) has found ways to capture nutrients in passing insects. This is one plant which puts more effort into capturing nutrients than sunlight.
Nertera scapanoides adapted to infertile, moist peat soils.
THE FOREST FOR THE TREES Hen and chicken fern/pikopiko (Asplenium bulbiferum) This fern is particularly easy to propagate from the bulbils that develop along the fronds and it grows particularly well in damp, shady places. Parataniwha (Elatostema rugosum) Parataniwha grows in profusion along stream banks wherever it is sufficiently Hen and chicken fern/pikopiko. protected from drought and bright sunlight. In these situations, it is a valuable ally in the campaign to restrict exotic weeds. Rasp fern/ pukupuku (Doodia australis) One of the most common and hardy ground ferns of the area, rasp fern will grow in full sunlight and significant shade.
Shining spleenwort (Asplenium oblongifolium) This is a common fern in drier, wellâ€“drained, shady places and often grows along fallen logs and tree fern trunks. Tree fern trunks are a great nursery for a wide variety of plants. No doubt shining spleenwort will eventually selfâ€“ introduce from the nearby scenic reserve, but early introduction will assist in the exclusion of weedy exotics.
Thread fern (Blechnum filiforme) Thread fern scrambles across the forest floor scavenging any sunlight which may have passed by higher layers of leaves but will entwine a tree trunk in order to enable its Rasp fern/ pukupuku. fertile fronds to access more sunlight. Thread fern (right).
Shining spleenwort. 118
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Conclusion We are faced with a choice ... an opportunity we mustnâ€™t lose
ur species has a dramatic impact on the landscape we inhabit; so much so that nothing on the surface of this planet has escaped human influence. We have built cities, roads and farms; we have moved species to areas they would never have arrived at by any other means. Without natural predators, grazers, parasites and diseases, some of these species have run rampant, seriously excluding those plants and animals native to an area. Areas long ago cleared of native vegetation are now more likely to be dominated by weedy imports than a healthy assemblage of native plants, with dire consequences. We are losing the natural character of the landscape. Populations of native species are fragmented and unable to migrate. Habitat for native animals is impoverished. The stabilising effect on water flows, water quality and climate that a healthy native plant community can provide is compromised. We have, frankly, initiated one of the greatest extinction events the world has known. But despite this catastrophic situation, there is hope. Because we have also developed an awareness of our influence on the environment and are working on some of the solutions. We just need the time, resources and, perhaps above all, commitment to work on these. We can contribute to the environment by planting native plants in previously unmanaged areas or on particularly sensitive places like riparian margins. The benefits of planting natives are dramatically increased if
we aim to restore the natural processes that govern a natural area and replicate the spatial and temporal patterns we find in nature. A natural plant community is a combination of native plant species with complementary strategies, each adapted in a unique way to capitalise on some of the available resources. Establishing an assemblage of species closely resembling a natural plant community helps ensure that all resources are used well, that weeds will have difficulty establishing and that the project will become more selfâ€“ sustaining. Many other parts of the world have a rich, manâ€“made heritage, but many of those countries have lost much of the natural heritage which we are inclined to take for granted. Restoration planting following natural patterns is not just a practical strategy but an imperative. Following the guidance provided here has the potential to protect and restore the unique character of a site, a district, a region and a nation. We are faced with a choice; to observe closely the natural patterns and processes found in the world around us and take care to faithfully restore them. To do less is to compromise resilience, expose the project and surrounding area to weed invasion and erode the biodiversity of the region. A fantastic opportunity would be lost. This means that for anyone propagating native plants for natural areas, it is important to propagate carefully following ecosourcing principles; for people planning and funding
THE FOREST FOR THE TREES projects, to make sure there is adequate provision for a long term and sustainable project or outcome; and for those restoring a natural area, to do their very best to familiarise themselves with the remaining remnants of native ecosystems in the area and use them as a guide.
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Further reading Some suggestions for broadening your knowledge
y far the most instructive source for this book has been Mother Nature herself. I cannot stress enough the value of visiting her regularly and taking lessons from her. But without the books and other resources available, filled with insight from those who have asked and sought out the answers to the important questions, I would have been searching in the dark. Here are some I have found helpful preparing this guide.
140 years later. Be warned, though: The book is a bit economical with full stops and generous with commas.
Dispersal in Plants: A population perspective. Calvin Dytham, Richard Law & Roger Cousens. Oxford University Press, New York, 2008. Any study of natural systems and how to replicate them requires an understanding of both dispersal and competition; the two most important factors that determine where an New Zealand as Ecosystems: The ecosystem organism is to be found and where it is not. concept as a tool for environmental This book provides a thorough introduction management and conservation. Geoff Park. into dispersal in plants. Department of Conservation, Wellington, 2000. The Theory of Island Biogeography. R.H. The author advocates for a wider landscape McArthur & E.O.Wilson. Princeton University approach to conservation, focusing on Press, Princeton, NJ, 1967. restoration of natural processes. The guide is Another classic which helps us understand available from: file:///C:/Users/D/AppData/ not only the current distribution of species, but Local/Temp/NZEcosystems_Completeâ€“1.pdf the possible outcomes of human intervention. The Nature Guide to the New Zealand New Zealand Ferns and Allied Plants. Patrick Forest. John Dawson & Rob Lucas. Random J. Brownsey and John C. Smithâ€“Dodsworth. House, Auckland, 2000. 2000 (Revised Edition). This is such a handy and accessible guide, it This is the authority I turn to when I need to is never far from my desk. identify ferns and find Maori names for them. On the Origin of Species by Natural Ecology and Field Biology. Robert Leo Smith Selection, Or, The Preservation of Favoured & Thomas M. Smith. Benjamin Cummings. 2001. Races in the Struggle for Life. Charles Darwin. I return time and time again to this general J. Murray, 1859. Available as an ebook. ecology text. To say this is a classic is a gross understatement. A dedicated naturalist and reflective theorist, Flora of New Zealand Volume I. Darwin still speaks with relevance more than H.H.Allan.1961 121
THE FOREST FOR THE TREES The official authority this is also useful for notes on habitat and Maori names.
Flora of New Zealand Volume IV: Naturalised Pteridophytes, Gymnosperms, Dicotyledons. C.J.Webb, W.R.Sykes & P.J.Garnock–Jones. Springer. This has useful information about not only the identification if weeds and naturalised species, but also the date they were first recorded as naturalised
Christchurch: h t t p : / / w w w. c c c . g o v t . n z / c i t y l e i s u r e / parkswalkways/environmentecology/ streamsideplanting/index.aspx This guide covers the planning of a project. More detailed guidance is available for related topics.
Propagation of New Zealand Native Plants www.nzpcn.org.nz Lawrie Metcalfe This is the first site I go to for information about both native and naturalised plants. Identification of Native Plants. Because it is a website, it is searchable, up Small leaved shrubs of New Zealand, Hugh to date and has good photos of most plants Wilson and Tim Galloway. found growing naturally in New Zealand. I find Wetland Plants in New Zealand, Peter the distribution data particularly useful. Johnson and Pat Brooke. The Nature Guide to the New Zealand The Society for Ecological Restoration (SER) Forest. John Dawson, Rob Lucas. has a really good 13–page introduction to ecological restoration which can be found at: Identification of Weeds http://www.ser.org/resources/resources– An illustrated guide to Common Weeds of detail–view/ser–international–primer–on– New Zealand Latest edition. ecological–restoration Threatened Ecosystems Although direct reference to natural areas Williams et al. (2007) New Zealand’s is always the best guide to understanding historically rare terrestrial ecosystems the distribution of species in a project, there set in a physical and physiognomic are some very useful regional guides which framework Available on–line at: http://www. should be consulted as well. Here are some I newzealandecology.org/nzje/ have come across. Regional councils may have others for their area. Waikato District: http://www.doc.govt.nz/getting–involved/ volunteer–join–or–start–a–project/grow– n a t i v e – p l a n t s / l o ca l – p l a n t i n g – g u i d e s / ecological–restoration–in–the–waikato/ Tasman District: http://www.tasman.govt.nz/environment/ land/biodiversity/restoration–planting–lists/ Auckland: http://www.aucklandcouncil.govt.nz/EN/ 122
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Appendix 1 Evaluating a restoration plan and monitoring its implementation
his section is intended to help those who require restoration work to be undertaken as mitigation for development which has significant environmental effects. This may also be a useful checklist for project managers, planners, funding organisations and compliance monitors. 1. A plan should describe the native vegetation found existing on the site and nearby, prior to implementation. It should list at least the significant weeds present or likely to appear. Other threats to vegetation such as animals, fire and flood should also be identified. 2. A plan should describe the plant community expected to develop as a result of the project and the trajectory the site is expected to follow towards the planned outcome. This will include the appearance of new weeds and how they will be controlled. A plan should describe how a community of native plants will establish and how this will change over time. Regeneration of planted species, the demise of early establishing species, dispersal of new species to the site and the outcome of competition between weeds and the native plant community is key to this. A plan may prescribe a project which progresses only part of the way to restoring this plant community, but if this is the case, the justification for this should be provided and future options for continuation towards sustainability discussed. 3. The plan should describe the reference
sites examined and any other references used during the preparation of the plan and justify both the description of the plant community adopted and the trajectory which is expected, based on analysis of appropriate reference sites. 4. The plan should then specify the weedâ€“ control effort required and outline a detailed planting strategy specifying species, quantities or densities, the appropriate habitat for each species and a timeline for its implementation. 5. The plan should include a monitoring and reporting programme which details the outcome of any trials, examples of how closely the project follows the predicted trajectory and details of any significant unexpected occurrences. If variance from the planned strategy, for instance substitution of species or delays in implementation, is unavoidable then this should be approved by the original plan designer or another suitably qualified person. The monitoring and reporting programme should be followed and verified with independent site visits from time to time. It may be helpful to require completion of one stage before the next stage is begun.
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Appendix 2 Forming and working with community groups
By Nardene Berry New Zealand Landcare trust
here is no doubt that a group of people focused on ecological restoration can achieve much more than a single person, and there are many examples of community groups working to restore natural areas in NZ. In general, groups usually have some sort of partnership with, or support from, their local Council or DOC office, local iwi or school. Websites such as Nature Space or the NZ Landcare Trust, DOC or Regional Councils list many community and care groups around NZ, but there may not be one near you. If you have a project area you would like support with, and would like to form a group to assist, here are some helpful tips that you may like to consider. You don’t have to do every step; these are just suggestions to help you on your journey. It is really useful to work with someone from a relevant agency who has a mandate to support local communities. You may be the most passionate person and drive the group, organise all the work and keep things going, but if you move, or can no longer do this for whatever reason, the group may well fall over. f course, this may not happen, but if you have someone from an agency whom can provide support when needed, this will help keep the group on track. Plus, there is someone to whom the group can be held accountable — even if in an informal way — so that if a group winds up, and many groups do, for a variety of reasons
— including achieving the outcome they set out to achieve — matters can be drawn to a conclusion in a professional manner. Do you want to be an informal group that just meets on a weekly basis to kill weeds and replant? Or do you want to form either an incorporated society or charitable trust so that you have more formal status? You can then more easily apply for funding (in some instances funding bodies will only consider applications from formal groups). There is a lot of information on the web about the key differences between an incorporated society and a charitable trust, and the pros and cons of each, what things you must legally do and so on. Two helpful ones are the Community Law website: h t t p : / / w w w. c o m m u n i t y l a w. o r g . n z / community-law-manual/chapter-2community-organisations-and-the-law/ choosing-the-right-legal-structure-for-yourgroup/ and the Companies Office website: h t t p : / / w w w. s o c i e t i e s . g o v t . n z / c m s / customer-suppor t/faqs/what-are -the differences-between-incorporated-societiesand-charitable-trusts When it comes to information about setting up meetings, financial management, keeping records and raising funds Community Net Aotearoa has a Community Resource Kit, which is very useful for groups starting out: http://www.community.net.nz/resources/ community-resource-kit/contents-of-thecommunity-resource-kit/ Once you have decided to become a legal
THE FOREST FOR THE TREES entity or not, the next thing would be to get others interested in joining your group. You may already have others interested in helping, or you may have to raise your profile as a group amongst your local community. One of the things most community groups struggle with is getting and keeping volunteers. There are many demands on people’s time, and volunteering with a community group is one more thing in an already busy schedule. Sometimes it’s easier for people to not volunteer. This is where your group needs to be savvy and draw on diverse sectors of the community. For example, you could enlist the local school to come once a term to help with weeding and/or planting. If you schedule it early enough in a school year, it is more likely to happen. Are there any Girl Guides or Scout groups you could ask to help out once or twice a year? How about local retirement homes? The residents might be able to help with potting up plants or weeding. Advertise in your local free community newspapers. There might be a coffee group of new parents who could assist with delivering fliers in letterboxes while they go for a walk. Thinking outside traditional ways of gaining volunteers may be needed, depending on where you live. Rural communities can be different from urban groups, and beach care groups different again. Jan Simmons who has worked for the Department of Conservation supporting community iniatives for many years provides some advice on forming and maintaining groups. ‘Providing an opportunity to make a tangible difference is important. In addition, being part of a conservation group is a great opportunity to learn about the environment and perhaps gain skills and experience for your own private project. ‘The Waikato weedbusters group regularly
visits a range of sites and works on weed control programmes on each. There is no better way to get to know a site than working on it. ‘Spending time especially in the company of others with a similar quest is an ideal opportunity to explore how a site came to be the way that it has and what will be required to restore natural values. ‘Of course, the social connections are important as well so always maintaining opportunities for meeting and mixing is essential.’
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About the author ... and a few people to thank
fter initiating the restoration of forest to the abandoned quarry where Wayne Bennett and his family made their home forty years ago, he set his sights on the Waikato Riverbank across the road. Two decades later, Wayne is older and hopefully wiser. Wayne now shares what he has learned through Forest Flora, the restoration nursery and consultancy he operates with his daughter Julia. Acknowledgements The ideas expressed in this book are not always my own original ideas. I am very grateful to landowners, restoration practitioners and scientists who have looked over this text and given constructive advice. Robyn Smith, Robyn Gedye, Jan Simmons, Catherine Beard, Leon Perrie, Peter De Lange, Chris Lusk and Paula Reeves. I also really appreciate Dave Leggett, Danielle Heyns and Kathryn Mercer reading over drafts, correcting errors and helping me express the ideas more clearly. Without the help of Josh Easby of Hurricane Press, this book would have remained a bland manuscript on my computer.
A guide to the ecological Restoration of native forest and wetlands in Waikato New Zealand, focusing on the use of ecosourced native trees s...
Published on May 14, 2019
A guide to the ecological Restoration of native forest and wetlands in Waikato New Zealand, focusing on the use of ecosourced native trees s...