PNGAF MAGAZINE ISSUE # 9 B-4 of 6th April 2021

AUSTRALIAN FORESTERS in PAPUA NEW GUINEA 1900-1975

PNGAF MAGAZINE ISSUE # 9B - 4 of 6th April 2021 RAINFOREST LIFE CYCLE AND FOREST DYNAMICS

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Rainforest Recovery after Harvesting Disturbance, North Coast PNG near Wewak.

Photo credit D McCarthy.

Editor R B McCarthy2 2021

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Rainforest recovery after harvesting disturbance. North Coast PNG near Wewak. Photo credit D McCarthy.

District Forester TPNG 1963-1975

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TABLE OF CONTENTS “FORWOOD”

page 3

Rainforest Life Cycle Forest Ecology Climax Vegetation Growth in the Climax Rainforest Mortality Pattern of Growth in the Rainforest

page 5 page 5 page 5 page 5 page 6 page 6

Forest Dynamics Forest Disturbance Forest Succession Components of Species Richness

page 8 page 8 page 8 page 9

Factors influencing Regeneration of Rainforest Species Flowering and Fruiting of Rainforest Trees National Tree Seed Centre Bulolo B Gunn et al Seed PNG Tree Species 2004 N Howcroft3 2002 Paper A. hunsteinii (Klinkii Pine) Seed Dissemination J Davidson4 Rainbow Eucalypt Man Germination Development of Regeneration Age Class Distribution

page 12 page 12 page 12 page 14 page 21 page 24 page 24 page 27 page 28 page 28

Nutrients and their Cycles within the Rainforest Ecosystem.

Rainforest Soils Shifting Agriculture

Page 30 page 30 page 31

Rainforest Silviculture

page 35

Bibliography

page 36

Acronyms

page 37

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Neville Howcroft Senior Research Technical Officer Tree Breeding TPNG Forests 1964-2017 John Davidson from Forestry Cadet to Forestry Professor TPNG 1962-1980.

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“FORWOOD” To understand rainforest management, it is necessary to examine the life cycle of climax rainforest vegetation. Herein lies the basis for successfully managing rainforest vegetation, or indeed, any vegetation.

Forest ecology is the scientific study of the interrelated patterns, processes, flora, fauna, and ecosystems in forests.

The general pattern of growth for any area of climax (mature) rainforest is one of an overstorey of large trees, most of which tend to be light demanders throughout most of their life. Beneath these trees, are one or more lower stories which contain both smaller individuals of over storey trees and mature trees of lesser stature. Large climbers are present in the upper canopy, epiphytes occur on the trunks and branches, shrub layers and in places, a herb layer are found in the undergrowth, while on the ground are fallen leaves, seedlings and seed.

Competition is severe and mortality amongst seedlings is high.

In PNG’s mixed rainforest stands, the actual composition is largely a matter of chance, depending not only on the size of the opening but upon the species present as seedlings and /or saplings when the opening is formed, and the climatic conditions that exist at the time of creating the opening.

Forest dynamics describe the underlying physical and biological forces that shape and change a forest ecosystem. The continuous state of change in forests can be summarized with two basic elements: disturbance and succession.

Rainforest silviculture is the manipulation of the forest to favour certain species and thereby enhance its value to Man. It is not a science (in its own right), but it is applied ecology.

The forester needs to understand all the factors involved in regenerating the more desirable species. This includes flowering and fruiting, seed dissemination, germination, distribution and development of regeneration, size class distribution, and pattern of growth leading to climax vegetation in the rainforest.

Rainforest soils tend to be generally infertile and deficient in plant nutrients. It is probably that infertility, which provides the main limit to production on rainforest sites. Rainforest plants are clearly adapted to making the best use of these infertile sites.

Sustainable utilisation of the rainforest depends on working within the limits of ecosystem nutrient cycles. Shifting agriculture works by using the capacity of trees to grow on acid infertile soils and bring nutrients from the soil into the biomass. During the bush fallow period, nutrients reaccumulate in the vegetation, partly from the soil and partly from rain.

Shifting agriculture and selective removal of trees do not cause serious permanent depletion.

More complete biomass utilisation for wood chips or in plantation forestry will deplete ecosystem nutrients unless balanced by rain and soil inputs.

The ecological basis of natural forest silviculture is the manipulation of the forest canopy. By controlling canopy gap size, it is possible to influence species composition of the next growth cycle.

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Rainforest silviculture will be successful so long as it is practised within the biological limits of the forest.

Foresters have no control over changes to the climate. Yet, forests are sensitive to climate.

Climate change can have a great effect on the dynamics of the ecosystem.

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RAINFOREST LIFE CYCLE Ecology (the study of the relations of animal and plant communities to their surroundings) is forestry’s fundamental science.

Forest Ecology Forest ecology is the scientific study of the interrelated patterns, processes, flora, fauna, and ecosystems in forests. The management of forests is known as forest management.

A forest ecosystem describes the community of plants, animals, microbes, and all other organisms in interaction with the chemical and physical features of their environment. Specifically, a terrestrial environment dominated by trees growing in a closed canopy – a forest.

Forests consist not only of living (biotic) components like trees, animals, plants, and other living things but also of nonliving (abiotic) components such as soil, water, air, and landforms. All these components together make up a forest ecosystem.

Climax Vegetation In consideration of rainforest management, it is necessary to examine the life cycle of climax (mature) vegetation. Here lies the basis for successfully managing rainforest vegetation or indeed any vegetation.

Climax vegetation occurs, when the general characteristic and composition of the vegetation remains broadly the same over a given area, for a period at least the life span of the longest living individual. Such climax vegetation is not a static community, but rather one that is immensely dynamic, showing constant change. The plants within the community, flower and produce seed. The seed is dispersed and germinates. Many of the seedlings are destroyed or die. Some seedlings survive for periods of varying length. The more mature plants grow and compete until old age or some other calamity, cause their death. The gaps produced by the dead trees form the focus for a burst of new growth by the seedlings and the immature trees in their vicinity. This constant repetition is the life cycle of the plants and of the forest itself.

The life cycle of growing and regrowing the rainforest is primarily concerned with regeneration and growth. Previously, general ecological influences affecting rainforest behaviour and development have been discussed.

Growth in the Climax Rainforest The growth of climax rainforest may be described as a study of domestic stagnation.

The environmental conditions of any site are only capable of supporting so much growth from the native species present. Source Anon.

Although in the fully stocked stands, there may be no net increment over a period of years, growth plots established in climax stands show, that with few exceptions, the individual trees are increasing in diameter each year, if only slowly.

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Many factors influence the growth of individual trees such as: • • • •

Crown condition where the faster growing stems have well developed crowns.

A proliferation of climbers in the canopy, depresses the growth rate.

Forest stocking of many stems.

A lack of water and other nutrients.

Mortality All trees must ultimately die.

Mortality in climax rainforest is an important phase of the rainforest cycle. This mortality is a continuous affair.

Factors affecting mortality of trees, seedlings and seed include: • • • • • •

Much of the viable seed produced is eaten or rots before it can germinate.

Young seedlings under dense undergrowth suffer heavy loss until conditions are suitable for them to assume height growth.

Seedlings may be browsed by animals or crushed by falling tree branches.

Competition for light, nutrients, and moisture from larger trees.

Damaging agencies as fire and/or strong winds e.g., cyclones.

As trees age, they become susceptible to attack by fungi and insects until they die.

It should be noted that for many rainforest trees isolated by the destruction of rainforest around them, they become prone to early death.

The Pattern of Growth in Rainforest – The general pattern of growth for any area of climax rainforest is one of an overstorey of large trees, most of which tend to be light demanders throughout most of their life.

Beneath these trees, are one or more lower stories which contain both smaller individuals of over storey trees and mature trees of lesser stature. Large climbers are present in the upper canopy, epiphytes occur on the trunks and branches, shrub layers and in places, a herb layer are found in the undergrowth, while on the ground are fallen leaves, seedlings and seed. Competition is severe and mortality amongst seedlings is high.

Mortality is also occurring above in the various tree storeys. In the lower storeys, completion for light, moisture and nutrients coupled with old age causes death. However, these trees die gradually and cause little disturbance when falling to the ground. Because the process is gradual, neighbouring trees of approximately the same size benefit. Their growth rate increases until they are again in full competition with each other.

In the uppermost storey, different influences are acting. Here the trees are large, and their canopies spread are considerable. Competition applies, but not as critical as at lower levels in the rainforest plant community. The upper storey trees are frequently suffering attack by fungi, insects and by old age. Eventually death does occur. As previously described, the death 6

and fall of one or more over storey trees creates patches of varying extent. It is within these patches, that rainforest regeneration occurs.

It could be stated that climax/mature/virgin rainforest is essentially a patchwork of even aged stands which have resulted from regeneration in the patches caused by the death of one or more over storey trees.

In PNG’s mixed rainforest stands, the actual composition is largely a matter of chance, depending not only on the size of the opening, but upon the species present as seedlings and /or saplings when the opening is formed and the climatic conditions that exist at the time of creating the opening.

Licuala Vanimo 1974. Photo credit Ian Whyte.

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Forest Dynamics Forest dynamics describe the underlying physical and biological forces that shape and change a forest ecosystem. The continuous state of change in forests can be summarized with two basic elements: disturbance and succession.

Forest Disturbance Forest disturbance are events that cause change in the structure and composition of a forest ecosystem, beyond the growth and death of individual organisms.

Disturbances can vary in frequency and intensity. They can include natural disasters such as fire, landslides, wind, volcanic eruptions, rare meteor impacts, outbreaks of insects, fungi, and other pathogens, animal-caused effects such as grazing and trampling, and anthropogenic disturbances such as warfare, logging, pollution, the clearing of land for urbanization or agriculture, and the introduction of invasive species. Not all disturbances are destructive or negative to the overall forest ecosystem. Many natural disturbances allow for renewal and growth and often release necessary nutrients.

Small-scale disturbances are the key to creating and maintaining diversity and heterogeneity within a forest. Small-scale disturbances are events such as single-tree blowdowns, which create gaps that let light through the canopy to the understorey and forest floor. This available light allows early successional shade-intolerant species to colonize and maintain a population within the dominant forest, leading to the complex spatial mosaic forest structure recognized as climax growth. This process is referred to as gap dynamics and has been described across many types of forests, including tropical, temperate, and boreal.

The sets and patterns of natural disturbances that characterize a particular area or ecosystem are referred to as the ecosystem's disturbance regime. A natural community is linked with its natural disturbance regime. For example, temperate and boreal rainforests typically have a disturbance regime consisting of high frequency but small-scale events, resulting in an overly complex forest dominated by incredibly old trees. In contrast, forests that have a disturbance regime consisting of high-severity stand-replacing events, such as frequent fires, tend to be more uniform in structure and have relatively young tree stands.

Forest Succession Forest succession is the process by which species recover and regenerate after a disturbance.

The type of disturbance, the climate and weather conditions, the presence of colonizing species, and the interactions among species, all influence the path that succession will take.

Species diversity and composition fluctuate throughout succession. The classic model of succession is known as relay floristics and refers to a relay of dominant species. After a stand-replacing disturbance, shade-intolerant species colonize and grow into a dominant canopy, but due to their shade-intolerance they are unable to regenerate under their own canopy; the understory (composed of shade-tolerant species) gradually replaces the canopy, and due to its shade-tolerance it can regenerate under its own canopy and therefore becomes the dominant species. Often succession is not so complete or directed as the relay floristics model describes. Species can be mid-tolerant of shade and survive by taking advantage of small amounts of light coming through the canopy, and further disturbances can create small 8

gaps. These and other factors can lead to a mixture of dominant species and a not so obvious “end” to succession. (Climax community).

In scientific ecology, climax community is an historic term for a forest community of plants, animals, and fungi which, through the process of ecological succession in the development of vegetation in an area over time have reached a steady state.

Many successional trajectories follow a basic four-stage development pattern.

The first of these stages, stand initiation, occurs after a major disturbance, and involves many species arriving into the area of abundant light and nutrients. The second stage, stem exclusion, describes the growth and competition of these species as resources become less available; likely one or a few species outcompetes and becomes stand-dominating. The third stage, understory reinitiating, involves further disturbance and the creation of gaps; at this point stratification develops, with layers of canopy, midstory, and understory appearing. The final stage, known as old growth, is the extension and completion of the understory. Thus, a complex multi-aged and multi-layered forest has again been developed.

Rainforest Recovery after Harvesting Disturbance. North Coast PNG near Wewak.

Photo credit Dick McCarthy.

Components of Species Richness Whitmore5 highlights that the dynamic nature of forest canopies, provides many different regeneration niches, to which different species have become specialised. Of the two broad classes, (climax and pioneer), there are fewer pioneer than climax species. The most species rich forested landscape will be one that includes patches of secondary forest recovering from some disturbance and patches of primary forest composed of climax species.

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T C Whitmore 1990. An Introduction to Tropical Rain Forests. ISBN 0194424480.

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Mile a minute vine. Rainforest recovery after harvesting. North Coast PNG near Wewak.

Photo credit Dick McCarthy.

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Post logging natural regeneration Open Bay TA 1974. Photo credit Ian Whyte.

Hibiscus Kleinhovea Regeneration Sagarai Gadaisu TA1976. Photo credit Ian Whyte.

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Factors influencing Regeneration of Rainforest Species The forester needs to understand all the factors involved in regenerating the more desirable species. This includes flowering and fruiting, seed dissemination, germination, distribution and development of regeneration, size class distribution, and pattern of growth leading to climax vegetation in the rainforest.

Flowering and Fruiting of Rainforest Trees The species found within the rainforest vary considerably in their flowering and fruiting habits.

Seed production is usually seasonal in the canopy, but in the undergrowth, flowers and fruits are often borne in small quantities or at irregular but frequent intervals. This is the situation where the climate shows relatively slight seasonal variation. However, where there is a more distinct seasonal effect, either from cold or a definite dry season, individual species tend to produce flowers and subsequently seed over a more limited period of each year.

Many of the more important rainforest trees demonstrate irregular flowering. This is reflected in even more irregular seeding, since flowering may, on occasions be accompanied by conditions unfavourable to pollination or be followed by heavy loss of immature fruit by insects, larger animals, or other causes.

Where the climate has a regular dry season, most species shed their seed either at the end of the dry season or during the first half of the wet season.

Understory species and many secondary species seem able to produce viable seed over much of the year.

The larger and more important forest trees are seasonal and maybe highly irregular in their fruiting.

If fresh seed had to be relied upon to produce new crops, organised silviculture in many rainforest areas would be impossible.

National Tree Seed Centre Bulolo Neville Howcroft6 established the National Tree Seed Centre at Bulolo to support reliable seed sources, genetic resources, and conservation aimed at ensuring the Department of Forests became self-sufficient in improved seed. A programme for seed species programs had already been initiated by Alan Cameron7 around 1962 for teak (Tectona grandis) and by Prof John Davidson8 for kamarere (Eucalyptus deglupta) in the late 1960’s. Previous work was also undertaken by Joe Havel9 and Leon Clifford10.

During these developments, Howcroft’s forestry duties became more diversified involving, forest protection with entomology, while in other areas leading into the establishment of tree breeding programs and seed orchard of several Pinus species using clonal and seedling seed 6

Neville Howcroft Senior Research Technical Officer Tree Breeding TPNG Forests 1964-2017.

Alan Cameron Cadet Forester to Senior Research Forester TPNG forests 1956-1970.

88 John Davidson from Forestry Cadet to Forestry Professor TPNG 1962-1980.

9 Joe Havel Cadet to Research and Regional Forester, then Inaugural Principal BFC TPNG Forests 1953-1965.

10 Leon Clifford Cadet to Research and Regional Forester then Acting Principal BFC TPNG Forests 1958-1975.

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orchard strategies). Howcroft trained staff and initiated PNGs first ever controlled pollination program to produce its first hybrids involving Pinus merkusii provenances and Pinus Latteri.

Shortly after this he became responsible for the Araucaria improvement and research program.

Howcroft was involved in the establishment of PNG partnering with FAO in the exploration of natural forestry resources and perceived conservation status, estimates of seed production, time, and ease of access, and to expedite collections for national and international provenance trials and to identify and recommend ex situ conservation stands. Initially, this involved PNG and West Papua species as Araucaria cunninghamii and A. hunsteinii as well as with Eucalyptus deglupta.

Further work developed programs for the National Tree Seed Centre under the direction of senior research staff such as Dr Barry Gray11 and Dr. John Davidson in collaboration with the Australia National Tree Seed Centre, ACIAR and overseas supporters and partners interested in specific PNG genera and species.

Through these connections, it was possible to secure assistance to get staff trained to collect and process tree seed more efficiently and to operate and develop the PNG National Tree Seed Centre.

This came into being after the break down of the original Bulolo cold store facilities which were used during a tragic air crash on the 28th of August 1972, of an Australian Army Caribou aircraft12, carrying school cadets. The recovery and storage of the deceased in this national tragedy was able to be carried out due to the National Tree Seed Centre being equipped with 4 large rooms operating at adjustable storage temperature. The facility was taken over in that emergency as nothing else existed to deal with the current situation at Bulolo or Lae. After all the forensic work had been completed, the bodies were repatriated to Port Moresby and eventually to their home provinces and families for burial.

Seed for PNG’s seed production had been returned to the cool rooms but by now the facility cool room structures started to collapse (due to chemicals used to store the bodies) and become unreliable for storing seed (including all the research seed). As the interior walls and roofing starting to collapse, it became difficult to maintain steady temperature at the required levels.

Before this unforeseeable event occurred, Howcroft had, with assistance, developed a proposal for a new seed store for the existing research centre. It was approved and established through New Zealand Aid. This prevented a seed storage crisis for national and international demand, but some losses in the seed viability, for the Araucaria seed collection occurred.

An important issue to be addressed re seed management (especially phenology), by the Australian government and thus the various PNG Government departments including forestry, was the academic and the industrial capacity building of new recruits and enrolled forestry students, including the field staff who had obviously started with the Bulolo Forestry College.

As one of many examples, a course in seed radiography was held at CSIRO Australian Tree Seed Centre, Canberra. Key PNG NTSC staff were selected and trained by the National Australian Tree Centre This was probably the first for Howcroft’s staff of the National Tree Seed Centre to travel outside of PNG. This form of capacity building continued after Howcroft transferred to Lae. 11 12

Barry Gray Forest Entomologist and Senior Research Forester TPNG Forests 1966-1974.

Murray Day “Bulolo Tragedy” PNGAF Magazine # 8 of 1 February 2021 p 81-82

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Howcroft enrolled himself with the University of Technology, Lae. He studied and undertook research on a terrestrial orchid genus part-time, while working at FRI, and earned a Master of Philosophy degree in 1994. On the 17th of November 2011 he was awarded an OBE for services to Eco-forestry and conservation of commercial tree species in the pacific (PNG).

Neville Howcroft was transferred from the Bulolo Research Station and National Tree Seed Centre to join FRI in Lae. However, he continued supervision of the newly established National Tree Seed Centre at Bulolo.

In 1995 he accepted a consultancy position to work as the project manager on the PNGFA/ITTO Balsa Project in East New Britain which did not start on time because of the September 1994 volcanic eruption at Rabaul. With selected PNG staff, he re-established the industry in the Gazelle Peninsula and introduced a tree improvement programme and improved tree seed program.

It was during this ITTO Balsa period, that he found that the teak genetic resources in the Islands was under threat. He was able to prevent these resources from being harvested. He was able to play a role in the protection of the Vunapalading Teak seed trees selected, with the help of his very capable assistant Mr. John Ohana. The Balsa Project leader position was localized at that time to Mr. John Ohana to ensure continuity when Neville completed his contract.

After a further short period of consultancy in East New Britain, Neville joined the Vudal University to establish a Forestry Department in the School of Natural Resources in July 2007.

Projects established over the period in collaboration with ACIAR included a further extension of Balsa research as a follow up to recommendations made by the previous ITTO project.

From experience, the most important project to follow, was the UNRE participation in the Teak Improvement program. This collaborative ACIAR program involved the PNGFA, FRI, as well as NGOs such as OISCA and others, effectively injected new life into the Teak tree breeding program started by Alan Cameron (1962). It followed and complimented the recommendations in a teak genetic resource survey report by Howcroft (2005).

Seed Handling and Propagation of PNG’s Tree Species 2004. B Gunn et al.

This project, led by Brian Gunn CSIRO and National Tree Seed Centre Bulolo PNG staff Alex Agiwa, Derek Bosimbi, Brioni Brammall, Lawrence Jarua, and Annonciata Uwamariya CSIRO), further developed programs initiated by Neville Howcroft and his staff at the NTSC. It resulted in publication of the Seed Handling and Propagation of Papua New Guinea’s Tree Species 2004. B Gunn et al. PNGFA & CSIRO publication ISBN 0643065318. The booklet was part of a project funded by ACIAR to provide additional information on the cultivation of PNG tree species.

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Cover Page of Seed Handling and Propagation of Papua New Guinea’s Tree Species 2004. B Gunn et al. PNGFA & CSIRO publication ISBN 0643065318.

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Back Page of Seed Handling and Propagation of Papua New Guinea’s Tree Species 2004. B Gunn et al. PNGFA & CSIRO publication ISBN 0643065318.

Information on flowering and fruiting of PNG Forest species is scant and often conflicting.

This makes it difficult to know when to collect seed, particularly for rainforest species that do not necessarily fruit on a regular annual basis.

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The publication provided phenological data as known for some PNG tree species. This data is a guide only as the timing of phenological development varies with altitude change and location for individual species.

In this PNGAF magazine #9 B-4, examples of the seed attributes of some of the selected PNG tree species with commercial potential are detailed. This reflects overall, the collective work to date undertaken by many contributors towards increasing PNG’s scientific tree data base.

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Most rainforest trees produce ripe fruit soon after flowering. An exception is some of the conifers such as Araucaria spp. (e.g., hoop and klinkii pine) which may take up to two years before the seed ripens.

N Howcroft 2002 Paper A. hunsteinii (Klinki Pine) PNG Neville Howcroft’13s in 2002 presented a paper at the Araucariaceae Symposium Auckland New Zealand March 2002 titled “Genetic Variation, Conservation and Silviculture of Klinkii Pine Araucaria hunsteinii in Papua New Guinea.”

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Neville Howcroft Senior Research Technical Officer Tree Breeding TPNG Forests 1964-2017

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Tree climber

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Cone and male flowers of Araucaria hunsteinii var klinkii from Garaina referred often to as Grey Klinkii by Howcroft. Photo Credit Neville Howcroft.

A collection of fertile cones of grey klinkii pine grafted clones at Bulolo National Seed Production area. Photo credit Neville Howcroft.

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Seed Dissemination Rainforest plants show many of the well-recognised devices for seed dispersal. There is a marked emphasis on animal dispersal (edible seeds) and in the uppermost tree layers, on wind dispersal.

Wind dispersal may be greater in some areas, notably the Dipterocarp rainforest of South East Asia and the Flindersia-Proteaceae-Tarrietia rainforest of North Queensland.

Animal dispersal occurs in two main ways. By birds, bats or less commonly, arboreal mammals eating the fruit from the tree, or by the fruit dropping to the ground and then being distributed by terrestrial animals and birds. This happens with the cassowary distributing seeds of Elaeocarpus in PNG and North Queensland.

The efficiency of animal and bird distribution is seen in the spread of such undesirable species as mistletoes, strangling Ficus spp, African tulip etc.

By contrast, some rainforest species rely on gravity to distribute their relatively heavy seeds such as Castanospermum spp and Elaeocarpus spp. The regeneration of such species is usually limited to small areas around the parent trees, unless flooding causes the seeds to be more widely spread.

John Davidson’s RAINBOW EUCALPYPT MAN – A Parallel Journey Professor John Davidson14 undertook extensive research with Eucalyptus deglupta (Kamarere) from the late 1960’s.

In studying the natural regeneration of E deglupta, he found the seeds were minute, numbering 1-7million, sometimes to 14 million, viable seeds per kg. the seeds are shed along with “chaff” comprising the aborted ovules and fragments of placentas. Each fully developed seed is elongate, flattish, with a characteristic tail like terminal wing. The hilum is ventral.

E. deglupta seed New Britain.

Photo credit Prof John Davidson.

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John Davidson from Forestry Cadet to Forestry Professor TPNG 1962-1980.

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Until Prof John Davidson’s work, authors had described the dispersal of seed by water to be deposited downstream on sand and gravelly banks to germinate profusely initially forming dense regeneration.

E. deglupta regeneration along riverbanks New Britain. Photo credit Prof John Davidson.

E. deglupta regeneration along riverbanks New Britain. Photo credit Prof John Davidson.

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Self-thinning takes place and several even aged cohorts may be present at a particular location.

E. deglupta stand New Britain. Photo credit Prof John Davidson 1968.

Prof John Davidson found that the lightness of the individual seed and its terminal wing gave E deglupta unique properties not found with seed of other eucalypts. Seed of E. deglupta was capable of relatively wide dispersal from individual parents at and above canopy level through being carried by wind. Being easily carried by wind currents explains how the species was able to colonize in an uphill direction, new volcanic material ejected by active volcanoes. Seeds were carried by updrafts generated during the eruptions, as distinct from being carried downhill by flowing water. So, dispersal was both uphill and downhill on volcanic crater cones.

Mount Ulawun is a basaltic and andesitic volcanic cone built up of alternate layers of hardened lava, pumice, and volcanic ash. It is situated on the island of New Britain, in West New Britain Province, Papua New Guinea. It is about 130 km southwest of Rabaul, the highest mountain in the Bismarck Archipelago at 2,334 metres, and one of the most active volcanoes in Papua New Guinea. The lower cone is clothed in almost pure stands of E. deglupta in several age cohorts.

Natural regeneration occurs in both an upward direction on new deposits through seed borne on updrafts and downward on the lower slopes where seed is deposited by water along the edges of the numerous incised rivulets. Brown patches are areas destroyed by fire during recent eruptions only to be recolonised later. Some palms are associated with stunted E. deglupta at the higher elevations. Casuarina sp coexists with E. deglupta at the lower elevations.

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Mount Ulawun Volcano New Britain. Photo credit Prof John Davidson.

Germination The seeds of rainforest species vary greatly in their longevity. Some, including most dipterocarps, lose their viability extremely rapidly. At the other extreme, some of the Acacias may retain their viability for up to 400 years in the soil.

Most species appear to germinate soon after seed fall (their viability is only for a short period), particularly when moisture conditions are favourable.

It has been suggested that the dense growth of weed species following disturbance of rainforest sites results from species invasion after the disturbance has occurred. However, evidence is against this. Trials on soil samples taken from beneath mature rainforest sites, show that when put into nursery germination trials, a proliferation of seedlings of different species including many shrubs, climbers and herbs germinate. It is apparent that this seed must have already been in the soil for a lengthy period awaiting suitable conditions to germinate. Increased temperature and possibly increased light appear to be the most likely factors in this surge of germination.

This ability for seed to remain viable in the soil for some time and then germinate after disturbance appears characteristic of many secondary rainforest species.

There are many rainforest tree species termed “gap opportunists”. These are tree species with seed of short viability, but where their seedlings are persistent and able to survive, without showing any appreciable development, under dense undergrowth between seed falls. If during this period, e.g., an old tree falls, the seedlings in the vicinity of the gap can make an immediate response with vigorous height growth. Species that fall into this category include 27

some of the more desirable rainforest species such as members of the Meliaceae, Dipterocarpaceae and Flindersia.

Development of Regeneration Once the seedlings (be they of trees, climbers, shrubs, or herbs) become initially established, factors again play a large role in determining their subsequent survival and growth.

Sites that have been the subset of severe disturbance (e.g., fire, harvesting, gardening, and climatic factors) regenerate rapidly, with species of secondary succession. These species will include those whose seed has been lying dormant in the soil and those who species whose seedlings are unable to survive beyond the cotyledon state, save in the presence of copious light.

The species found in these large gaps are of mixed botanical relationships, though in the tropical rainforest, the families Euphorbiaceae (Macaranga, Mallotus) and Moraceae (Musanga, Cecropia) often are prominent. Climbers are extremely well represented, and many of the species are protected by spines and thorns or stinging hairs.

Where fire has not been involved, there may be a seedling stocking of intolerant but persistent species as light hardwood Shorea spp and many climbers and climbing palms.

Unburnt disturbed sites will also produce coppice regrowth from any of the knocked down smaller saplings.

All these plants grow with great rapidity. It is not unusual for secondary species to reach heights of 2 to 3 metres in the first year.

For the first few years, the thicket maybe almost impenetrable, but soon the lower branches die and the stands thin out beneath, allowing entry into the young regrowth stand.

Most of the extreme light demanders which dominate this phase of regeneration are relatively small, short lived trees (some only shrubs) usually producing soft, light timber. Few species last more than 20 years. Most species are of little economic value although a few produce desirable timbers e.g., Ochroma lagopus (balsa).

More persistent seedlings, present when the disturbance occurs, also respond to the increased light, and make rapid growth, although they seldom grow as fast as the extreme light demanders. These develop with thicket conditions and although many may be lost by the severe competition in the mass of regeneration, a proportion survive and tend to take over dominance of the thicket as the short lived but initially faster growing stocks die. They include Shorea spp and Flindersia spp. These species show a marked response to increased light and although they may have existed as small seedlings for several years in the undergrowth, they retain the capacity to commence height growth almost immediately conditions become favourable.

Age Class Distribution Previously, it was noted that the stocking of Climax/Mature/Virgin Rainforest sites vary considerable in size classes. Within these communities, most stems and species occur in the smaller size classes.

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Wait a While Vine, Calamus muelleri Vanimo.

Photo credit Ian Whyte 1974.

This slender cane-like climbing palm is armed with hooked spines on its leaves, stems, and tendrils. These spines aid its climb towards the canopy, but also excel at catching clothing and flesh of any passerby.

In Australia, aborigines used the tendrils as fishhooks and to extract witchy grubs from their holes. The outer fleshy layer of the fruit was eaten. The sap was drunk to provide relief from colds and chewed and swallowed to prevent dysentery.

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Nutrients and their Cycles within the Rainforest Ecosystem.

Rainforest Soils Previously in PNGAF Magazine # 9 B-2 of 25th March 2021, (p 13-14) rainforest soils nutrient status was described. The soils on which the rain forests grow tend to be shallow and poor in nutrients. This has been described as “deserts covered by rainforest”. The explanation lies in the closed nutrient cycle, which the vegetation sets up. The high growth rates and intense biological activity of the forest is based upon a quick recycling of organic waste material back into the growing plants.

This issue is well known and there are many global examples of disastrous attempts at land settlement where people have ignored this phenomenon of trying to farm on the infertile rainforest soils. In many areas, if the trees are removed and the land is used for agriculture, the nutrient cycle is broken and the inherent lack of fertility of the soil is quickly revealed.

If after clearing a rainforest site, forest vegetation can redevelop on those sites, the closed nutrient cycle can be gradually re-established. The speed of the re-establishment depends on the initial fertility of the soil. Typically, secondary succession back to rainforest occurs and the slow increase in the ecosystem’s nutrient cycle provides the basis for the widespread shifting cultivation and bush fallow agricultural systems of the humid tropics. These systems, however, rely on sufficient time to elapse between successive clearings for the nutrient content of the ecosystem to build up to a level akin to that in the mature rainforest. If the population pressure is such that insufficient time elapses between successive clearings, then soil degradation of an almost permanent nature will occur.

Rainforest soils tend to be generally infertile and deficient in plant nutrients. It is probably that infertility, which provides the main limit to production on rainforest sites. Rainforest plants are clearly adapted to making the best use of these infertile sites.

Soil is a most important factor in rainforest management and one that cannot be appreciably altered by management. It provides definite limitations on what can be achieved by forest management. Hence, care must be taken when selecting species for tree growing schemes that are suited to the soil type and location. e.g., Acacia mangium will not grow on swampy sites but many Terminalia spp will.

In many tropical rainforests, most nutrients are evenly distributed between above and below ground parts of the ecosystem. Nutrients are added to all forests in rain. Forests on young shallow soils also receive nutrients from decomposing rock. But on old deep soils, the soil parent material is beyond the reach of roots, there is no nutrient addition, and these soils are commonly less fertile.

Nutrients cycle through the ecosystem. The main pathways are rain, canopy fall, and litter fall. Fine litter decomposes within months of fall. Soil invertebrates as termites, are important litter decomposers in the lowlands.

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Shifting Agriculture Whitmore15 described shifting agriculture as a farming method that has been invented independently, in all parts of the tropics. It has proven sustainable since time immemorial.

It is a low input system, suitable for infertile rainforest sites. Crops are grown for one or two years and then bush fallow, of secondary forest allowed to grow for 8-10 years and then repeat the cycle. Crops cannot be grown for too long because the soil becomes impoverished and acid and pests, diseases and weeds increase.

Shifting agriculture works by using the capacity of trees to grow on acid infertile soils and bring nutrients from the soil into the biomass. During the bush fallow period, nutrients reaccumulate in the vegetation, partly from the soil and partly from rain.

Highlands Grassland and interface with rainforest vegetation

Fallow regimes

Village site

Middle Ramu TA. Impact of Shifting Agriculture. Photo credit Dick McCarthy.

Bourke16 described shifting cultivation in 2009 as the basis for most food production in PNG. Most agricultural systems in the lowlands are shifting cultivation systems that use only long fallows to maintain soil fertility. The exceptions occur where food is derived from tree crops such as sago, coconut, or breadfruit or from some sweet potato-based systems in the highlands where land is rarely fallowed.

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T C Whitmore 1990. An Introduction to Tropical Rain Forests. ISBN 0194424480 Bourke, R.M. and Harwood, T (eds) 2009. Food and Agriculture in Papua New Guinea. ANU Press.

ISBN 9781921536618 (pdf).

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Although shifting cultivation is commonly associated with burning, some 20 % of PNG’s shifting cultivators do not burn slashed fallow vegetation during the preparation of plots for cultivation. Most of the non-burning systems are found in the high rainfall areas or where sago is a major food source.

In the lowlands, one to three plantings are typical, with then fallows of between 5 to 15 years.

Fallow regimes Village site

Gazelle Peninsular East New Britain Impact of Shifting Agriculture. View to Raunspena past Kalivit 1967. Photo credit Ian Whyte.

Fallow regimes

Old village site

Block 6 Vanimo Impact of Shifting Agriculture. Photo credit Ian Whyte 1974.

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Gogol TA near Madang, Impact of Shifting Agriculture. Note various fallow regimes. Photo credit Ian Whyte 1971

Fallow regimes

New garden sites Note individual owners.

Fallow regimes

Old village site

Old access road

Open Bay TA. Impact of Shifting Agriculture. Photo credit Ian Whyte 1974.

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New garden sites with individual owners

Papuan Coast near Kupiano/Cape Rodney. Impact of Shifting Agriculture coupled with change in vegetation types from Rainforest to Eucalypt Savannah. Photo credit Dick McCarthy.

Papuan Coast near Kupiano/Cape Rodney. Impact of Shifting Agriculture coupled with change in vegetation types from Rainforest to Eucalypt Savannah. Photo credit Dick McCarthy.

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Rainforest Silviculture Rainforest silviculture is the manipulation of the forest to favour certain species and thereby enhance its value to Man. It is not a science (in its own right), but it is applied ecology.

The forester needs to understand all the factors involved in regenerating the more desirable species. This includes flowering and fruiting, seed dissemination, germination, distribution and development of regeneration, size class distribution, and pattern of growth leading to climax vegetation in the rainforest.

Sustainable utilisation of the rainforest depends on working within the limits of ecosystem nutrient cycles. Shifting agriculture and selective removal of trees do not cause serious permanent depletion. More complete biomass utilisation for wood chips or in plantation forestry will deplete ecosystem nutrients unless balanced by rain and soil inputs.

Rainforest soils tend to be generally infertile and deficient in plant nutrients. It is probably that infertility, which provides the main limit to production on rainforest sites. Rainforest plants are clearly adapted to making the best use of these infertile sites.

Soil is a most important factor in rainforest management and one that cannot be appreciably altered by management. It provides definite limitations on what can be achieved by forest management. Hence, care must be taken when selecting species for tree growing schemes that are suited to the soil type and location. e.g., Acacia mangium will not grow on swampy sites but many Terminalia spp will.

The ecological basis of natural forest silviculture is the manipulation of the forest canopy. By controlling canopy gap size, it is possible to influence species composition of the next growth cycle.

Rainforest silviculture will be successful so long as it is practised within the biological limits of the forest.

Foresters have no control over changes to the climate. Yet, Forests are sensitive to climate, and so climate change can have a great effect on the dynamics of the ecosystem. Rising carbon dioxide levels can increase the productivity and growth of trees, which will then decrease as other nutrients become limiting. Changes in temperature and precipitation can affect the success of various species and the resulting species assemblage. Many factors of climate change can also affect an ecosystem’s disturbance regime, making the forest prone to susceptibility to different disturbances and altering or even preventing recovery after a disturbance.

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Bibliography George Baur. The Ecological Basis of Rainforest Management. Andre Mayer Fellowship 1961-62. FAO. Barry Conn and Kipiro Damas. Trees of Papua New Guinea Vol 1-3 www.pngtrees.com Bourke, R.M. and Harwood, T (eds) 2009. Food and Agriculture in Papua New Guinea. ANU Press. ISBN 9781921536618 (pdf).

Dept of Forests PNG. New Horizons. Jacaranda Press 1973 ISBN0701681845.

Gunn B et al 2004. Seed Handling and Propagation of Papua New Guinea’s Tree Species 2004. PNGFA & CSIRO publication ISBN 0643065318.

Hammermaster ET and Saunders J C 1995 FOREST RESOURCES AND VEGETATION MAPPING OF PAPUA NEW GUINEA PNGRIS publication #4. ISBN 0642196087.

J. J. Havel (1972) New Guinea Forests—Structure, Composition and Management, Australian Forestry, 36:1, 24-37, DOI: 10.1080/00049158.1972.10675567.

J. J Havel (1975). Training Manual for the Forestry College Vol.3 Forest Botany. Part 2.

Botanical Taxonomy. Dept of Forests Port Moresby PNG. Bob Johns 1976 Common Forest Trees of Papua New Guinea Parts 1-12. Training Manual for the Bulolo Forestry College PNG. T C Whitmore 1990. An Introduction to Tropical Rain Forests. ISBN 0194424480.

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ACRONYMS ACT ACIAR AEC AFS AFPNG AIF AMF ANBG ANGAU ANU APMF APPM ASIO ASOPA BCOF “Beer Time” BFC BGD BUC C cm CALM CFA CNGT CRE CRE

CSIRO CHAH DASF DEPT DOF E.g.

Etc FAO F &TB FPRC Forkol GIS ha IBRD IFA ITTO

Australian Capital Territory Australian Centre for International Agricultural Research Administrators Executive Committee Australian Forestry School Association of Foresters of PNG Australian Infantry Forces Australian Military Forces Australian National Botanical Gardens Australian New Guinea Administrative Unit Australian National University Australian Paper Manufacturers Forestry Pty Ltd Australia Paper and Pulp Manufacturers Australian Security Intelligence Organisation Australian School of Pacific Administration British Commonwealth Occupational Force 1945-52 Any time.

Bulolo Forestry College Bulolo Gold Dredging Company Bulolo University College Commonwealth Centimetre Western Australian Department of Conservation and Land Management Commonwealth Forestry Association Commonwealth New Guinea Timbers Bulolo Commander Royal Engineers CRE is a term inherited by RAE from RE and is the term for the Commanding Officer of a RAE unit which is headed by a Lt Col. Although the officer is called the CRE the name is also used for the name of his unit. E.g., CRE Aust Forestry Group or 1(NG Forests).

Commonwealth Scientific and Industrial Research Organisation Council of Heads of Australasian Herbaria Dept of Agriculture, Stock and Fisheries Department Department of Forests For example et cetera (more of the same) Food and Agriculture Organisation Forest and Timber Bureau Canberra Forest Products Research Centre Hohola Bulolo Forestry College Geographic Information Systems Hectare International Bank for Reconstruction and Development Institute of Foresters of Australia International Tropical Timber Organization 37

L of N m3 MM NAA NARI NB no.

NG NGF NGIB NGO NGVR NZ NSW NTSC OISCA P or p PIB PIR PNG PNGAA PNGAF PNGFA PNGFIA PNGRIS PNGUT POM Q QF RAE RPC SFM SP UK UN Unasylva UNE UNI UNITECH UNRE UPNG UQ US USA TPNG TUBL TA TA TRP

League of Nations cubic metre Military Medal National Archives Australia National Agriculture Research Institute New Britain Number New Guinea New Guinea Forces (relates to plant collection of Lae Herbarium) New Guinea Infantry Battalion Non-Government Organisation New Guinea Volunteer Rifles New Zealand New South Wales National Tree Seed Centre PNG Bulolo Organisation for Industrial, Spiritual and Cultural Advancement International Japan. page Papuan Infantry Battalion Pacific Islands Regiment Papua New Guinea Papua New Guinea Australia Association Papua New Guinea Australian Foresters Magazine Series Papua New Guinea Forest Authority PNG Forest Industries Association Papua New Guinea Resource Information System PNG University of Technology Port Moresby Queensland Queensland Forestry Royal Australian Engineers/Australian Army Royal Papuan Constabulary Sustainable Forest Management South Pacific United Kingdom United Nations Journal of FAO of UN University of New England Armidale NSW University University of Technology Lae PNG University of Natural Resources and Environment University of Papua New Guinea University of Queensland United States United States of America Territory of Papua and New Guinea Territory United Brewery Ltd Timber Area Timber Authority Timber Rights Purchase 38

VSF WA WB WW2

Victorian School of Forestry Western Australia World Bank WORLD WAR 2

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