The Axe, autumn 2014 by Ian McDermott

AN AXE TO GRIND. MTOA’s QUARTERLY MAGAZINE

New look Axe, Autumn 2014 Edition. Interactive content; where you see the leaf logo then the page

Meet this edition’s contributors If you click on any of the pictures you can read their on-line biography. Where you see “Feature Article” the piece is unique to the Axe! Jeremy Barrell

Francesco Ferrini

Gareth Hare

Richard Nicholson

Chris Parker

Glynn Percival

Kenton Rogers

Moray Simpson

Ian McDermott If you are reading this edition of the Axe on PDF then please ensure you have the view option set for a two page spread, it is designed for on-line viewing so make use of the links embedded.

Editor

The MTOA is a fully constituted not for profit organisation . The views expressed in the magazine may not reflect the official views of the MTOA and the association accepts no liability for any views or technical advice presented by its contributing authors.

is ”live” so click for any internet content, try it

Inside this issue: Features Moray Simpson, Chairman's stump.

Francesco Ferrini, Air Temperatures

Jeremy Barrell, Insights for Tree Risk Managers

Glynn Percival , Potential Pest and Disease Threats

Kenton Rogers, Urban Forest Management

Chris Parker, Beech Woodwart

Gareth Hare, Yellow Birch.

Richard Nicholson, Big Belly Oak

And finally, Editors last word

Please don’t forget to visit the MTOA’s sponsors too.

Upcoming Events. September MTOA Tree Health AA Conference APF

October NHS Forest Conference

The Chairman’s Stump.

ISA Conference ATF study tour

MTOA Chairman, Moray Simpson.

November SMA Conference

December MTOA AGM

Please submit your calendar dates to the Editor

Front cover picture. Liriodendron tulipifera, that this year have been magnificent but please see the article on page 14! Picture courtesy of Karan A. Rawlins, University of Georgia.

n recent weeks we have being enjoying the fine summer weather, but at times the summer heat has been quite uncomfortable, well at least for me as a Scotsman, it has. I’ve welcomed the shade provided by trees in the town where I work and in streets where there are no trees, I have sought shade from buildings. I do not like extreme heat and have no desire to be sunburnt and end up with skin cancer or cataracts, both by-products of being exposed to too much sunlight. Buildings by there shear size do provide welcome shade, but largely, trees are much nicer to look at and also built structures don’t ameliorate local climates by evapotranspiration. In the midst of the recent heatwave, I was thinking about what to write for the “Axe” and I couldn’t decide. Probably, because I find it hard to think when I’m getting frazzled by the sun and the heat is pointing my mind in one direction only; where can I get a cold beer from! So when an MTOA colleague, Portia Howe, passed on a link to the government’s “Heatwave Plan for England 2014”, I thought that’s topical. So my article is about trees being part of the solution to the ill effects that extreme summer temperatures have on our health. I strongly believe that people’s health and wellbeing is inexorably linked to the health and wellbeing of our urban forests. Healthy urban forests = healthier humans. In relation to high summer temperatures and the detrimental effects that this can have on human health, it is imperative that urban forestry is recognised by Local Health boards as a means to preventing human health problems and mortality. Local Authorities should be planting

trees and managing our existing trees to provide shade in public spaces and school grounds and we should be planting and protecting existing trees to help reduce air pollution and the urban heat island. We also have to bear in mind that climate change will make matters much worse. According to the latest UK Climate Projections, UKCP09, the UK will experience hotter and drier summers and more very hot days. In fact, the UK Government’s Supplementary Green Book “Accounting for the Effects of Climate Change” predicts that there will be more frequent periods of temperatures exceeding 35°C and because the effects of excessive heat on health can be severe (including death), the Department of Health has introduced an annual Heatwave Plan to ensure the country is prepared for future heatwaves. This supplementary “Green Book” guidance recommends long-term planning to adapt and reduce the impacts of climate change (HM Treasurer/ DEFRA, 2009). The “Green Book”, along with the “Orange” and “Magenta” books, is the UK government’s guidance for the appraisal and evaluation of policies, programmes and projects. Climate change means heatwaves. (HM Treasurer/ DEFRA, 2009).

The English “Heatwave Plan” (there is a Welsh Heatwave Plan, but not sure if there is a Scottish plan) recommends long-term planning to adapt and reduce the impacts of climate change. This is another reason for tree and urban forestry strategies to plan for the long-term, rather than is still all too common, the short-term. Outdoor air pollution causes 35,000 – 50,000 premature deaths per year In the UK (Environmental Audit Committee, 2010). Air pollution causes annual health costs of roughly £15 billion to UK citizens (DEFRA, 2010). There was a major heatwave across much of Europe in the first two weeks of August 2003, during which temperatures peaked at a new record of 38.5° C in the UK. The UK Office for National Statistics have reported an excess of 2045 deaths in England and Wales for the period from the 4th to 13th August 2003 above the 1998-2002 average for this time of year. Previous studies have suggested that a significant proportion of the excess deaths during heatwave conditions can be associated with the elevated concentrations of air pollutants

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rather than a direct effect of high temperatures (Stedman, J. R. 2004). Trees remove air pollution by the interception of particulate matter on plant surfaces and the gaseous pollutants through the leaf stomata. Trees affect air quality through the direct removal of air pollutants, altering local microclimates and building energy use, and through emission of volatile organic compounds (VOCs), which can contribute to O3 and PM2.5 formation (Nowak et all, 2014). Air pollutants which are harmful to human health are nitrogen dioxide (No2), Ozone, sulphur dioxide and small size particulate matter (PM10), all of which cause and exacerbate pulmonary and cardiac diseases (Department of Health, 1998 & Pope, C. A. 2004). So, increasing our urban tree populations, paying particular attention to species we’re planting, so we do not have too high a percentage of VOC emitting species, will help reduce air pollution. Trees change summer urban micro-climates for the better by creating shade and allowing cooler air to accumulate and circulate at ground level. Planting trees and vegetation and the creation of green spaces to enhance evaporation and shading are other options, as temperatures in and around green spaces can be several degrees lower than their surroundings. Trees also help to reduce the air temperature by the cooling effect of evaporation. Trees ‘transpire’ water, releasing large amounts of moisture into the air. One large tree can release 200 to 300 gallons of water on a summer day. Studies suggest that airconditioning demand can be reduced by up to 30 per cent through the effects of well-placed trees. There is considerable evidence to support the case for well-designed green infrastructure: trees, parks, green roofs, and

ponds/lakes can all help to reduce heat retention. (Public Health England, 2014). In summary, urban green space and trees can have the following beneficial effects: ·

reduces urban heat islands – predictions for urban temperatures over the next 70 years show that if there is less than 10 per cent urban green cover, urban temperatures will increase by about 8.2°C, whilst if green cover exceeds 10 per cent it will keep temperatures to only 1°C above current temperatures;

reduces pollution – each year 1.3 million trees would remove 2,535 tonnes of pollutants from the air (Public Health England, 2014).

So who’s at risk from extreme summer temperatures? Well, Public Health England states that anyone living in urban areas is at risk, with those over the age of 75 and young children and babies being categorised as high risk groups (Public Health England, 2014*). The “Heatwave Plan for England” recommends that commissioners of health and social care and local authority Directors of Public Health undertake long term planning to prepare for, and mitigate, the impact of heatwaves. So what’s the relevance of this to municipal arboriculturists and urban foresters? Well, The English Heatwave Plan recommends that, as part of the aforementioned long term planning, environmental action be undertaken to mitigate against the detrimental affects of heatwaves on health; i.e. that trees and green spaces are increased (Public Health England, 2014*). Research by Lancaster University indicates that if the number of trees is doubled by planting up all possible sites in the study area (West Midlands) particulate air pollution could be reduced by 25%. This could lead to a reduction of 140 deaths each year in the study area (Centre for Ecology & Hydrology/ Lancaster University).

Looking closer to home, well where I work, Wrexham County Borough, we have figures from the 2014 Wrexham I-tree eco study for the amount of air pollution removed by our urban trees and how much money this saves in health damage costs. Wrexham’s urban trees remove 60 tonnes of air pollution, including NO2, ozone, SO2, CO and PM10 and PM2.5 each year, which equates to a saving of more than £650,000.Ozone showed the greatest reduction by urban trees, demonstrating that although trees can increase ozone levels by producing VOC’s, they remove far more than they produce (Rumble, 2014). To finish off, here’s some more relevant facts taken from Centre for Ecology & Hydrology/ Lancaster University document “Trees & Sustainable Urban Air Quality: Using Trees to Improve Air Quality in Cities” report. ·

Trees benefit human health.

Trees positively affect air quality.

Trees provide shade & humidity.

Mature mixed woodland captures airborne particles at approximately three times the rate of grassland. The proportion of available area planted with trees has a direct affect on the resultant reductions in particle concentrations (see figure 1). Trees remove airborne pollutants at three times the rate of grassland. Trees at the edge of woodland are more effective at removing atmospheric pollutants than trees in the centre of woodland. This is due to both larger leaf areas and greater exposure to wind. Overall, the effects on air quality of very large scale planting of almost all tree species in urban areas would be positive (Centre for Ecology & Hydrology/ Lancaster University). (Continued on page 8)

Figure 1. Table showing that increase in planted land leads to decrease in particulate pollution.

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References Centre for Ecology & Hydrology/ Lancaster University. Trees & Sustainable Urban Air Quality: Using Trees to Improve Air Quality in Cities. http://www.es.lancs.ac.uk/people/cnh/ UrbanTreesBrochure.pdf Department of Health. Committee on the Medical Effects of Air Pollutants: Quantification of the Effects of Air Pollution on Health in the United Kingdom. The Stationery Office; London, 1998. http:// webarchive.nationalarchives.gov.uk/2014050 5104658/http://www.comeap.org.uk/ documents/reports Environmental Audit Committee. Fifth Report: Air Quality; The Stationery Office, London 2010. http://www.publications.parliament.uk/pa/ cm/cmenvaud.htm HM Treasurer/ DEFRA. Accounting for the Effects of Climate Change. Supplementary Green Book Guidance, June 2009. https://www.gov.uk/government/uploads/ system/uploads/attachment_data/ file/191501/ Accounting_for_the_effects_of_climate_chang e.pdf Nowak, D.J. et all. Tree and Forest Effects on Air Quality and Human Health in the United States. Environmental Pollution 193, 2014, Pages 119-129. http://www.fs.fed.us/nrs/pubs/jrnl/2014/ nrs_2014_nowak_001.pdf Pope, C. A., et all. Cardiovascular Mortality and Long-Term Exposure to Particulate Air Pollution. Circulation 2004.

http://circ.ahajournals.org/ content/109/1/71.full Public Health England. Heatwave Plan for England – Making the Case: the impact of heat on health – now and in the future. Public Health England & NHS England. May 2014. https://www.gov.uk/government/ publications/heatwave-plan-for-england Public Health England. Heatwave Plan for England – Protecting health and reducing harm from severe heat and heatwaves. Public Health England & NHS England. May 2014*. https://www.gov.uk/government/ publications/heatwave-plan-for-england Rumble, H. et all. Valuing Wrexham’s Urban Forest – Assessing the Ecosystem Services of Wrexham’s Urban Trees: A Technical Report. Forest Research/ Treeco2nomics, June 2014. Stedman, J. R. The Predicted Number of Air Pollution Related Deaths in the UK during the August 2003 Heatwave. Atmospheric Environment Volume 38, Issue 8, March 2004, Pages 1087–1090. http://www.sciencedirect.com/science/ article/pii/S1352231003010203 DEFRA. Air Pollution: Action in a Changing Climate. DEFRA Publications. March 2010. https://www.gov.uk/government/uploads/ system/uploads/attachment_data/file/69340/ pb13378-air-pollution.pdf

Moray Simpson MTOA Chair.

(Editor’s note; please also see the article on page 14.)

HELLENIC ASSOCIATION FOR

ARBORICULTURE e are pleased to announce the foundation of the Hellenic Association for Arboriculture (HAA).

infrastructure towards the fulfilment of the aforementioned goals.



organizations of similar scopes in both Greece and abroad along with the representation of Greece, with member status, in the European Arboricultural Council (EAC), a similar organization based in Germany.

The foundation of the HAA was the fruit of our efforts for synergy and interdisciplinary approach in the field of Arboriculture in Greece, which started with an open-call discussion in late 2012. Its 20 founding members include people from a broad range of disciplines (arborists, agriculturists, foresters, landscape architects) coming from both public and private sector backgrounds. The association is based in Athens and its goals, as stated in its Charter, are:



The promotion of Arboriculture in Greece, with regards to the protection, conservation, management, and care of (mainly) urban trees.



The development and dissemination of knowledge and the raising of consciousness regarding modern practices in Arboriculture.

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The conduct and support of activities relevant to the protection of (mainly) urban trees in Greece and the participation in similar activities abroad.



The utilization of all potential resources, being from national, municipal, European, or other authorities, for the implementation of projects that are consistent with the aforementioned activities, such as the conservation of urban trees through Arboriculture and ultimately the protection of the urban environment.

The Association has been legally recognized with the 5/02–04–2013 court order of the Athens County Court, and has received the registration number 29524 in the Book of Associations of the Court of First Instance of Athens. Anyone over 18 years old with an active interest in Arboriculture in Greece can become a member of the Association. You can communicate with the Association via: info@dendrokomia.gr.

The promotion of actions that aim to the protection and conservation of (mainly) urban trees.



The collaboration with associations and

The creation of a collaboration and information network for the provision of technical and scientific assistance to initiatives of both local and national scale, along with the establishment of

Minas Tsakiridis President, HAA.

Revised Planning Practice Guidance. When preparing Local Plans and taking planning decisions local planning authorities should pay particular attention to integrating adaptation and mitigation approaches and looking for 'winwin' solutions that will support sustainable development. This could be achieved in a variety of ways, for example: · by maximising summer cooling through natural ventilation in buildings and avoiding solar gain; · through district heating networks that include tri-generation (combined cooling, heat and power); or · through the provision of multi-functional green infrastructure, which can reduce urban heat islands, manage flooding and help species adapt to climate change – as well as contributing to a pleasant environment which encourages people to walk and cycle. Local planning authorities should be aware of and avoid the risk of maladaptation (adaptation that could become more harmful than helpful). For example, designing buildings to maximise solar gain in winter without thinking through the implications for overheating in summer. Sustainability appraisal and, where required, Environmental Impact Assessment, can be a useful for testing the integration of mitigation and adaptation measures and the long term implications of decisions

Let it not be said that a belt and bracers approach was not tried here. A memorial Oak planted for a deceased student in the Arboretum of a very well known and respected land based college is pictured. It has a total of three full stakes, six ties with poorly placed spacers and a cane that is wired to the stem â&#x20AC;&#x153;just in caseâ&#x20AC;? or maybe itâ&#x20AC;&#x2122;s just left on from the nursery. It has long been a bug bear of mine that the quality of tree planting is generally in the UK simply awful. This season alone has seen over forty trees in the streets of Walsall alone snapped off at the top of the (single low) stake after the council went back to its old ways of planting using unskilled staff, heart-breaking for everyone and entirely avoidable. However, given that we are now doing this on the college grounds in front of arboriculture students then this will be the approach with our incoming young arborists. I fear the situation will never improve.

Comments?

The Axe hits around the World. The Axe continues to grow and just in the last month (July 2014) saw the Summer 2014 edition go over 1000 readers and hit quite a variety of countries as can be seen from the screenshot (left). As expected we are big in the USA but it is both surprising and welcome that we have readers in Uganda and Kenya! Contributions are welcome and keep sharing!

Air temperature, and its effect on tree physiology and on tree pests under climate change

ome of the most severe impacts of climate change may result from an increase in the frequency and intensity of extreme climate events, rather than from gradual changes in mean conditions. Drought, in particular, is likely to become more common in many areas due to increasing temperatures and shifting precipitation as reported by William et al. (2011) especially when it will be associated by high temperatures. As stated by Nardini et al., (2013), “according to current understanding, three potential mechanisms can explain drought-induced tree desiccation and death: hydraulic failure (resulting from cavitation-induced embolism); carbon starvation (resulting from depletion of carbohydrate reserves during prolonged stomatal closure); biotic agents attack resulting from climate-driven outbreaks of insects and pathogens. These mechanisms are not necessarily mutually exclusive. In fact, embolism-avoidance mechanisms or hydraulic failure per se might cause stomatal

closure, leading to reduced photosynthetic rate and carbon starvation. In turn, carbon starvation and related impairment of phloem functioning might inhibit mechanisms responsible for refilling of embolized conduits or ion-mediated compensation of embolism- induced drop of xylem hydraulic conductance, thus exacerbating the droughtinduced reduction of water transport capacity. Finally, carbon starvation might reduce the production of metabolites involved in plant defence strategies, thus favouring attacks by biotic agents which may lead to further xylem blockage” (see below). As for the temperature trees and shrubs generally have optimum growing conditions across the range of temperatures from 20°C to 30°C. It is known that tree physiology can be negatively affected by hot temperatures (as mentioned especially if matched with drought) which can injure and kill living plant systems (i.e. deciduous trees very frequent show curling, bending, rolling, mottling, marginal browning (scorching), chlorosis,

shedding and early autumn coloration of leaves, in response to hot temperature, drought and high irradiance). Under environmental condition in which water availability may limit growth, abnormally high temperatures can alter normal energy flows and can increase both respiration and transpiration. However, trees can dissipate tremendous heat loads if allowed to function normally. Unfortunately, hot temperatures greatly increase the water vapour pressure deficit (VPD)(dryness of the air) which cause leaf stomata to close because of rapid water loss and limits transpirational cooling. When transpiration is limited by hot temperatures, plant tissue temperatures can rise above the

thermal death threshold. According to what found in the literature we can state that a thermal death threshold is reached at approximately 45째C though it varies depending upon the duration of hot temperatures, the absolute highest temperature reached, tissue age, thermal mass, water content of tissue, and ability of the plant to make adjustments to temperature changes (for example in species with a large chilling requirement, milder winters might result in inadequate chilling and hence delayed and erratic bud burst in spring).

Urban trees with leaf withering due to drought stress

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The main statement is that a tree must always be in equilibrium with its environment. Any time this equilibrium is altered, the tree is stressed and must spend extra energy to survive. Trees can only react to their environment in genetically pre-set ways. Due to the climate warming this equilibrium is always more frequently altered and temperature rising due to global change is widely predicted to profoundly affect trees by altering photosynthesis and respiration,

of several insect species, as well as changes in seasonal phenology. Based on some models and on some references in the most recent literature is highly probable that insects will have the potential to be a major problem for urban trees under climate change. As reported in specific research it is extremely difficult to predict with any confidence the impact of climate change on insect pests, but it seems ascertained that their distributions will change. Impacts on urban tree species are also uncertain, as much of current scientific work in this area

Species selection is fundamental when planting in warm climates. In this case a Tulip tree shows more leaf wilting and dieback compared to the more tolerant Small-leaved Linden tree

soil organic matter decomposition and mineralisation, phenology and frost hardiness, species distributional changes, and adaptation and evolution. Also, higher temperature may indirectly affect the expansion range and the damages

has focused on forests species. The impact of facultative pathogens such as sooty bark disease of sycamore (Cryptostroma corticale) may worsen, while some insect pests that are present at low levels, or currently not considered important, may become more prevalent. Examples of the latter include

defoliating moths and bark beetles. Some authors described since early 60â&#x20AC;&#x2122;s the potential for the incidence, severity and northern ranges of disease to increase should climate factors, which normally act as constraints against outbreaks, become altered. Others predicted an increase in tree injury and death from insects and pathogens, acting as a single agents resulting from a warmer and drier climate. Predicting future pest and pathogen trends is difficult because of the fine balance between pest/pathogen, the health of the host tree species, and any natural defence mechanisms/pest predators. However, stressed trees are more susceptible to insect pests and diseases, and many insect pests are likely to benefit from climate change as a result of increased breeding activity and reduced winter mortality. Further, an increase of temperature may alter the mechanism by which the insects adjust their cycles to the local climate, resulting in faster development and higher feeding rate or in changed feeding attitudes. In addition, exotic insect species may be able to persist and become sometimes catastrophic under warmer temperatures where they might previously have been controlled by colder temperatures. The introduction and establishment of such exotic species such as the Asian longhorned beetle (Anoplophora glabripennis and A. chinensis) and the emerald ash borer (Agrilus planipennis) also in Europe may be easier and more likely under warmer climatic conditions. Drought has been shown to increase insect feeding activity due to increased concentrations of carbohydrates in foliage under dry conditions. Climatic conditions also affect the virulence and the number of generations of other insects like horsechestnut leaf miner (Cameraria ohridella) or can extend to the northern latitudes some parasites typically present in the warmer climate where they have natural

enemies (es. Rynchophorus ferrugineus on palm trees, a dreadful insect which has changed the typical landscape all over the Mediterranean countries by killing hundreds of thousands Canary palms and now also feeding on other palms). Also an increasing number of studies have reported on shifts in timing and length of the growing season, based on phenological, satellite and climatological studies. This can alter the physiology of trees and interact with the dormancy mechanisms. We know that trees are able to survive the cold winters after sequential physiological events, leading to build up of dormancy and cold resistance. These processes are normally initiated by environmental signals from decreasing photoperiod and temperatures. After the e st a b l i s h me n t of d o r ma n c y, low temperatures are necessary to break the physiological dormancy. The sum of chilling temperatures needed for the break of winter dormancy varies for different species and ecotypes. After chilling needs are fulfilled, bud break will happen when temperatures are high enough. This will result in changes in phenophases mainly consisting in advances of the spring phenophases and delay in the autumn phenophases and it is to be underlined that climate changes may cause uncertain ecological consequences, with implications for ecosystem stability and function in urban environment. The added effects of warming due to the city structures and the general climatic change may give a rather large increase in temperatures in cities. If the higher temperatures initiate the trees to decrease the tolerance to low temperatures, the trees may be more susceptible to damages from spells of spring frost. Urban tree management must meet these challenges and the role of research must be (Continued on page 18)

(Continued from page 17)

promoted and funded. Increased emphasis should be placed on selection and/or breeding trees for environmental stress tolerance, such as drought and temperature stress. Tolerance or resistance of trees to environmental stress will result in healthier trees that are not only able to resist disease, but will notably improving the quality of the urban environment. It is our opinion that the main strategy for protecting trees from the adverse effects of climate change and for maximizing their benefits on the urban environment and on human well-being, consists in developing long term management and replacement programmes which will ensure a balanced age range and a good tree health.

Francesco Ferrini

Mediterranean sclerophyllous vegetation under climate change: from acclimation to adaption. Environmental and Experimental Botany. Vol. 103: 80–98. 5. Chmielewski F.M., Rötzer T., 2001. Response of tree phenology to climate change across Europe., Agr. For. Meteorol., 108:101-112. 6. Cleland E.E., Chuine I., Menzel A., Mooney H.A., Schwartz M.D., 2007. Shifting plant phenology in response to global change. Trends in ecology and evolution, 22(7): 7. Cooke J.E.K., Eriksson M.E., & Junttila O., 2012. The dynamic nature of bud dormancy in trees: environmental control and molecular mechanisms. Plant, Cell and Envir., 35:1707-1728. 8. Hänninen H., Tanino K., 2011. Tree seasonability in a warming climate. Trends in Plant Science, 16(9):412-416. 9. Körner C., Basler D., 2010. Phenology under global warming. Science, 327:1461 -1462.

Department of Agrifood Production and Environmental Sciences – University of Florence (Italy)

10. Linderholm H.W., 2006. Growing season changes in the last century. Agric. For. Meteor., 137:1-14.

1. William. A. H., R. M. Marchin, P. Abit, ON L E E L., 2011. Hydraulic failure and tree dieback are associated with high wood density in a temperate forest under extreme drought. Global Change Biology 17, 2731–2742, doi: 10.1111/j.13652486.2011.02401.x

12. Menzel A., et al., 2006. European phenological response to climate change matches the warming pattern. Global Change Biol. , 12:1969-1976.

Citations

2. Nardini A., M. Battistuzzo and T. Savi, 2013. Shoot desiccation and hydraulic failure in temperate woody angiosperms during an extreme summer drought. New Phytologist 200: 322–329 doi: 10.1111/ nph.12288 4. Bussotti F., F. Ferrini, M. Pollastrini, A. Fini, 2014. The challenge of

11. Lu P., Yu Q., Liu J., Lee X., 2006. Advance of tree-flowering dates in response to urban climate change. Agric. For. Meteor., 138:120-131

13. Mimet A., Pellissier v., Quénol H., Aguejdad, Dubreuil V., Rozé F., 2009. Urbanisation induces early flowering: evidence from Platanus acerifolia and Prunus cerasus. Int. J. Biometeorol., 53:287-298. 14. Way D.A., 2011. Tree phenology responses to warming: spring forward, fall back. Tree Physiol., 31:469-471.

—one of the reasons we exist.

o you remember the front cover of the last edition of the Axe? Well in case you can’t it’s reproduced on the left. It featured a collapsed rotten Lombardi after the February storms that had fallen across some play equipment in the local park. The top picture features a new installation of equipment. The trees in the foreground is a 20m Acer pseudoplatanus and yes, that is a large wound at the point where the trunk bends slightly over the new equipment. As an organisation we have struggled for many years to engage fully with Landscape Architects and Park Managers and we continue to do so despite offering genuine good value CPD in all area’s of tree management and maintenance. As long as the above decisions are still being made to install a high value fixed target in the fall zone of a tree with a clear defect then the work of the MTOA must continue to strive to educate and engage with those colleagues who clearly need our expertise. See the article overleaf if you need more convincing.

o far, 2014 has been a busy year for legal judgments and inquests resulting from harm that has arisen from tree failures. In this article, Jeremy Barrell references three that he has been involved in, drawing out practical aspects that he thinks may be of value to arboriculturists, managers and duty holders charged with managing the risk from trees. Jeremy offers this selection of observations from his perspective as an arboriculturist and they should not be taken in any way to be a definitive analysis of the law, which is beyond his expertise to provide.

Legal judgments relating to tree failures Much of my work as a consultant focuses on advising duty holders on how to manage their trees so that, in the event of an incident where harm arises, they are in a strong position to defend allegations of negligence. Whether you are a tree officer, with direct responsibility for tree safety, or a consultant acting as an advisor, obvious issues of concern to duty holders include: 1) do their trees need inspecting at all and, if so, how often; 2) what sort of inspection is necessary; and 3) what credentials should an inspector have to undertake the task? You can find out more about answering these questions in this paper, Balancing tree benefits against tree security: The duty holder's dilemma (Arboricultural Journal, Volume 34, Issue 1, 2012), that can be downloaded at www.tandfonline.com/action/ showMostReadArticles? journalCode=tarb20#.U9N_TmdOVLi. In that paper, I explain that legal judgments, in tandem with many other considerations, can offer some value through insights into how the courts view specific issues. However, such cases are few and far between

in the tree world, with only nine published in the last decade. Furthermore, each of those cases only deals with a limited number of very narrow issues specific to each set of circumstances, which often limits the potential for meaningful interpretations. Finally, the reliability of those interpretations is further diluted because significant legal weight is only given to cases that go to appeal to become authorities, with Micklewright -v- Surrey County Council being the only case out of the nine to achieve that status.

More about inquests At the time of writing that paper, I had little experience of acting as an expert witness at inquests, and so did not include them in my analysis. However, more recently, there have been a number of inquests relating to deaths from falling branches, which may be of interest to tree managers, with two so far in 2014 (see below). In general terms, an inquest is a fact-finding enquiry to establish who has died, and how, when and where the death occurred (www.judiciary.gov.uk). It is a form of public enquiry to determine the truth and is intended to be inquisitorial. This is a different thrust from the adversarial

approach adopted in criminal and civil trials. Furthermore, the inquest verdict cannot be framed in such a way as to appear to determine matters of criminal or civil liability. Through the Coroners and Justice Act 2009, coroners now have a statutory duty (as opposed to a previous discretion) to issue a report to any person or organisation where the coroner believes that action should be taken to prevent future deaths. These are called prevention of future deaths (“PFD”) reports and it is the stated intention of the Chief Coroner that they encourage change for the better. There is a presumption in favour of publication and as many as possible are publicised on the judiciary website. These are deemed to be important instruments of change and they can be applied to deaths associated with tree failures. From a review of the published PFD reports, I have not discovered any so far that have been issued relating to tree failures, but the indications are that is soon about to change!

Inquest into the death of Michael Arthur Warren on 5th October 2012 This Inquest was heard in front of Mr Peter Bedford, the Senior Coroner for Berkshire, and lasted for three days, from 8–10 July 2014, at Windsor Guild Hall. Three tree expert witnesses were called; Dr Frank Hope appeared on behalf of Bracknell Forest Borough Council, Mr Henry Girling appeared on behalf of Mr Warren’s family and I was instructed by the Coroner. Horticulture Week reliably reported on this, with a short overview of the case available at m.hortweek.com/inquest-report-expectedwider-national-interest/arboriculture/ article/1304974.

The incident was caused by the sudden failure of a large and severely unbalanced branch overhanging the road that fell and hit Mr Warren’s car. There was significant internal decay near the point of failure, which lay behind a large pruning wound that had fully occluded, hiding the decay. After hearing all the evidence, the Coroner issued a Narrative Verdict that concluded: “The combination of visual signs was sufficient to have caused the landowner, his agent or a Highway Inspector to request a more detailed inspection of the oak tree by qualified Tree Officers. Such an inspection, on the balance of probabilities, would have identified the unbalanced nature of the branch and the large occluded wound which, in turn, would have led to more detailed examination. This, in turn, would have resulted in intervention works to the oak tree significantly reducing the risk of the branch falling as it did on 5th October 2012.” The Coroner also advised that he would be sending a PFD Report to Bracknell Forest District Council relating to the training of inspectors checking trees and the manner in which drive-by inspections are carried out. This PFD Report is not yet publicly available and so its detailed content still remains unknown. However, due to the scale of highway inspections around the UK that have to include trees, it is likely to be of national interest once it is available. This incident reflects my accumulating experience that severe imbalance of large branches or whole trees, in combination with other weakening conditions, is regularly associated with failures that cause harm. My observations indicate that where the imbalance really is severe, i.e. it looks obviously wrong, and there are other potentially weakening conditions, e.g. declining health or structural defects, inspectors should be vigilant when assessing

the potential for failure. This particularly applies to large old wounds on mature trees that have fully occluded, because the lack of any external signs of decay can be taken to imply that there is no significant weakness. That may well be the case on young trees that are growing rapidly and have compensated for any weakness. However, older trees growing more slowly may not be able to put on sufficient reaction wood to adequately compensate against the inevitable decay that arises from the wounding, which may result in a gradual weakening over time. There is no automatic implication that large occluded wounds on mature trees are always a problem, but my observations suggest that they should be carefully considered when assessing the potential for failure. Inquest into the death of Erena Wilson at the Royal Botanic Gardens Kew (“RBGK”), on 23 September 2012

This Inquest was heard in front of a Jury and lasted for three days, from 11–13 June 2014. In addition to evidence provided by RBGK, Dr David Lonsdale provided expert evidence on behalf of the Assistant Coroner and I appeared as the expert witness instructed by Erena Wilson’s family. Horticulture Week responsibly reported on a daily basis as the Inquest proceeded, and these updates can be reviewed at: ·

m.hortweek.com/inquest-hears-evidencedeath-2012-erena-wilson-hit-fallingbranch-rbg-kew/article/1298465

m.hortweek.com/second-day-inquest2012-death-kew-erena-wilson-hit-fallingbranch-hears-further-evidence/ article/1298662

m.hortweek.com/death-kew-visitor-hitbranch-accidental-inquest-finds/ article/1299047

One of the main issues explored at the hearing was whether the branch failure was due to Summer Branch Drop, a loosely defined condition used to group branch failure events that occur on mature trees during the summer with no obvious cause. RBGK asserted that the cause of the failure was due to a combination of wind and rain; Dr Lonsdale thought the cause was something “akin” to Summer Branch Drop; my view was that it was Summer Branch Drop because it exhibited more than enough of the characteristics commonly associated with such events. After hearing all the evidence, and after less than an hour of deliberation, the Jury returned a verdict of accidental death, stating that “there is insufficient evidence to establish the cause of the branch failure”. As reported by Horticulture Week, the Inquest also heard evidence about the nature of the tree management regime in place at the time of the accident, but the finding of insufficient evidence to establish the cause of failure meant that the Jury did not have to comment on these management issues. Subsequently, Horticulture Week wrote two further articles that can be reviewed at: ·

m.hortweek.com/kew-death-2012accident-inquest-rules/article/1300552

m.hortweek.com/summer-branch-dropwarnings-wanted/arboriculture/ article/1304973

Again, these provide a balanced analysis, but I add a short clarification on the following statement within the most recent, “However, a jury found that the death was an accident with summer branch drop not the cause, and Kew was not at fault”. This seems slightly at odds with the Jury’s verdict: “there is insufficient evidence to establish the cause of the branch failure”. My interpretation of the verdict is that the Jury could not establish the cause, which does not rule out Summer

Branch Drop, as implied in the article. Despite the Assistant Coroner’s expert and myself aligned on the point that the cause was something “akin” to Summer Branch Drop, with me being more confident that it was Summer Branch Drop, the Jury were not convinced and hence the specific wording of the verdict. During the lengthy preparation for this case, I worked closely with Mr Wilson and his legal team, researching previous incidents of Summer Branch Drop and its management on an international level. Those investigations revealed that Summer Branch Drop may not be as rare as first thought and there may be justification for rethinking the mantra often quoted that the risk is so low, it does not warrant any precautionary measures. These are important matters that I am continuing to work on, with a more detailed analysis anticipated for publication later this year. Stagecoach South Western Trains Ltd -vHind & Steel In December 2009, a substantially decayed stem of a large ash tree fell from a private property in Stains and damaged a train causing over £300,000 worth of damage and consequential costs. The written judgment for this High Court case can be downloaded at www.bailii.org/ew/cases/EWHC/ TCC/2014/1891.html, and the judge found in favour of both defendants. There is a very useful review of the legal authorities and principles relating to a landowner’s duty in paragraph 68 of the judgment. Legal commentators report how the Judge held that Ms Hind’s (the first defendant) duty in respect of a tree on her land had extended no further than the carrying out of periodic inspection through informal observation. In the absence of any trigger or warning sign of problems with the tree, there was no requirement to instruct a more detailed

inspection by an arboriculturist. She was not required to clear ivy to inspect the base herself or instruct an arboriculturist to do so. The tree had been worked on before the accident by the second defendant tree surgeon, Mr Steel, but he had not been asked to consider the health or safety of the tree. The claim against him also failed because he did not owe a duty of care to warn of any structural instability, which could only have been discovered through a close inspection. Through my involvement as the expert witness for Ms Hind, I pull out two issues that may be of interest to UK tree managers: Ivy: In my experience, ivy and its potential to hinder the discovery of defects regularly crops up in cases, with questions about whether it should be removed as part of a risk management regime. To date, there is no definitive answer, but recent cases provide some clues as to how the courts may view this. In Micklewright -v- SCC, the experts agreed that “It would not be standard practice to remove heavy ivy from a tree during a quick visual check.”, which has a compelling logic in the context of the vast numbers of trees that large landowners have to manage. However, because it was agreed between the experts, it was never tested in the proceedings, and so that reference is unlikely to carry any significant weight. In this Stagecoach judgment, the matter of ivy was considered in more detail, with the Judge stating in paragraph 86: “I reject the suggestion that as a reasonable and prudent landowner, Ms Hind was obliged to carry out inspections of the trunks of each of her apparently-healthy trees, no matter how difficult they were to access, and no matter how much they might be covered in ivy. A reasonable and prudent landowner in Ms Hind's position was not obliged to struggle her way through the nettles and brambles to the foot of what appeared to be a healthy

tree, in order to pull off some of the ivy leaves and then strip off the lattice work of ivy stems from the base of the Tree in order to look for decayed areas behind the ivy.” Whether such an analysis could extend to a formal inspection by an arboriculturist remains to be clarified, but this judgment does shed light on the likely expectations from a homeowner implementing an informal checking regime. National Tree Safety Group (“NTSG”) informal observations: At paragraph 53, under Published Guidance, this judgment refers to the NTSG guidance that informal observations may be used as a means of checking trees. For this case, it was unchallenged that this was a legitimate form of inspection; it was held that Ms Hind was able to carry out such an inspection and did so properly. This is the first judgment since the NTSG document was published that has directly referenced the informal observations approach to inspections and, no doubt, many homeowners will feel that it is a welcome clarification on the nature of their obligations. However, it does not automatically follow that larger landowners, who may have greater resources, can rely on informal observations as being sufficient for all types of circumstances. This is an aspect that still requires clarification. Finally, I am aware of suggestions that there may be some significant similarities between this case and Poll -v- Bartholomew because both centred on multi-stemmed ash trees with included bark unions. Having been involved in both, my opinion is that no meaningful comparisons can be drawn between these two cases on those grounds. Take-home points There is nothing radically new here and not much of this should come as any surprise to the wise tree inspector. However, in the

same way that refresher training is helpful in keeping up-to-date with specific skills, being alerted to emerging concerns that arise from legally oriented analysis can also be valuable. Some obvious reminders include: · Refresher training is an important element of keeping current · Drive-by tree inspections of roadside trees should be done at slow speeds · Spotters undertaking drive-by tree inspections of roadside trees should only be looking at trees, and not trying to detect highway defects in the same operation · Large occluded wounds on old trees should be carefully considered · Severe imbalance of large branches or whole trees should be carefully considered, especially in combination with other predisposing factors to failure · Summer branch drop is a known risk to specific groups of trees and that risk may be elevated at the end of extended dry summer periods followed by rain · There is unlikely to be an automatic presumption to remove ivy when inspecting trees, but further investigations

may be required if there are obvious indications of a potential problem · Informal inspections are likely to be acceptable for homeowners, but it is unclear whether the same applies to larger landholders Although such reminders can be useful, they cannot be a substitute for careful analysis that brings to bear the experience of the assessor on the specific circumstances of each situation. Knowledge, experience and common sense remain the cornerstones of effective tree risk management, and anyone still searching for simplistic formulaic solutions should brace themselves for disappointment. Read more about assessing the potential for tree failures in the articles at http:// www.barrelltreecare.co.uk/resources.php. Keep up to date with tree risk management developments on Jeremy’s Facebook page at https://www.facebook.com/pages/HeritageTree-Management/573985506028429.

A local authority and a tree surgeon have been sentenced for safety failings after a worker was injured when a tree he had been felling landed on a railway line and was hit by a train. Peter Wood was carrying out tree work for Mark Anthony Connelly near Ryton, Tyne & Wear, next to the Newcastle to Carlisle railway line, on 11 January 2012. Newcastle Crown Court heard yesterday (4 July) that Connelly, trading as Practical Conservation Management, was contracted by Gateshead Metropolitan Borough Council to remove two poplar trees that were in danger of falling onto the track. During felling, one of the trees twisted and fell onto the railway line, uprooting another tree on its way. Connelly and Wood tried to cut the tree away from the track, but while doing so failed to hear an oncoming train, which hit the tree. As a result, Wood sustained a fractured right ankle, a cut to the head and bruising. The court was told the cost to Northern Rail for repair of the train was more than £97,000, while a further £7,000 was incurred by Network Rail on callout, materials, machinery hire and delays to services. Network Rail had not been told about the felling operation near its line.

An investigation by the Health and Safety Executive (HSE) found that Gateshead Council failed to take reasonable steps to ensure that Connelly was competent to carry out work on large trees, such as checking if he had the relevant qualifications. Had it done so, it would have found out he was not, in fact, so qualified. HSE also found Connelly failed to put safety measures in place that would have prevented the tree falling towards the line. Gateshead Metropolitan Borough Council was fined £40,000 and ordered to pay £5,854 in costs after pleading guilty to breaching Section 3(1) of the Health and Safety at Work etc Act 1974. Mark Anthony Connelly was sentenced to 150 hours of unpaid work and ordered to pay £5,854 in costs after pleading guilty to breaching the same Act. After the case, HSE inspector Jonathan Wills said: "Mr Wood's painful injury and Northern Rail's unexpected bill for almost £100,000 could all have been avoided. "The decision to fell a mature poplar tree on a steep slope within falling distance of an active railway line without informing Network Rail and not using a precautionary winch was indicative of Mr Connelly's poor planning."

Barcham Trees is to hold a conference which is claims will be the biggest arboriculture event of its kind held in the UK. The Big Barn Conference to be held at its headquarters in Ely, Cambridgeshire, on 17 June 2015. Event organiser Barcham sales director Keith Sacre said he expects 550 delegates to attend the free event to hear the views of international arboriculture experts. Forestry Commission England’s principal advisor on arboriculture. Jim Smith will speak about the London i-Tree Project, Frederic Segur and Ian Sear will talk about tree management in Lyon, France and Melbourne, Australia, respectively and Dave Nowak of the USDA will speak about urban forest management, the importance of inventory and the role of i-Tree. Mike Raupp from the University of Maryland, USA, will speak about pests and diseases, Henrik Sjoman from the University of Alnarp, Sweden and Nina Bassuk Cornell University, USA will talk about tree species selection, while Cecil Konijndijk van den Bosch University of Alnarp, Sweden will share his knowledge on Urban Forest Governance. Dr Mark Johnston, a speaker on the history of urban forestry, who chaired the Trees, People and the Built Environment conference at Birmingham University last month, will also chair this event. "We believe our 2015 Big Barn Conference will be the biggest arboricultural gathering of its kind ever held in the UK, and I am delighted we have nine speakers from three continents to make the day a truly international event," said Sacre.

Places are offered on a first-come, first-served basis from 1 October and will include lunch and refreshments.

NHS Forest conference “Creating Healing Environments”- 7th October 2014, Guild Park at Lancashire Care NHS Trust. This year, the NHS Forest conference focuses on “Creating Healing Environments”, and will celebrate and share some of the wonderful activities, ideas and site developments in the NHS Forest over the past few years. The plan for the day includes; a) Presentations b) Interactive workshops and c) a site visit to Lancashire Care’s Guild Park near to Preston, whose Grow Your Own project won the overall NHS Sustainability Day Award this year. The NHS Forest will be making awards at the event, to celebrate the achievements at the

project sites. We are pleased to announce that, thanks to a generous donation, we are able to offer four categories of awards each with a £200 cash prize including: • Largest Number of Trees Planted • Most Innovative Site • Best Community Engagement • Most Pioneering Use of Green space by Healthcare Professionals An overall winner will receive an additional £200. You can book your place through Eventbrite; the cost is £30. Some free places are available for those who might otherwise be unable to attend. Please contact Mary Zacaroli for further details. Sarah Dandy NHS Forest Co-ordinator e: sarah.dandy@sustainablehealthcare.org.uk

Potential Pest and Disease Threats With increased global trade and international travel the threat of exotic pests and diseases has never been higher. In this, the first part of a two part article, Dr Glynn Percival from the Bartlett Tree Research and Diagnostic Laboratory based at the University of Reading discusses potential pest and disease threats to UK and Irish trees that are of concern to managers of trees and shrubs within our urban forests as well as outline potential management strategies that may be employed if, or when, outbreaks occur. In the Winter edition Dr. Percival will look at Hemlock Woody Adelgid, Bacterial Leaf Scorch and Thousand Canker Disease of Black Walnut. Introduction

emerged in the past 8-10 years demonstrates

With international trade in untreated wood

how new environments with few bio-control

and wood products, coupled with increased

predators and new host plants can result in

global

rapid

travel,

introduction

the

likelihood

exotic

pathogens

and

decay

becoming

established

pests, fungi

the

disease

and

their

infection

and

establishment.

The

potential impact, if further more damaging exotic

pests

and

diseases

were

deleteriously

introduced, would not only be the loss of

affecting the health status of the UKâ&#x20AC;&#x2122;s native

newly planted trees, but the loss of decades

and plantation forests, and amenity trees is

of effort and investment in tree plantations,

now a realistic possibility. For example acute

as well as irreparable damage to UK native

oak

biota and wood resources.

decline,

sudden

and

oak

death,

oak

processionary moth, Pseudomonas bleeding

This article highlights a number of potential

canker, horse chestnut leaf miner are now

pest and disease threats causing concern to

considered serious threats to the health and

professionals in tree and shrub production,

future longevity of many UK trees. The fact

planting and management regarding the

that these pests and diseases have only

likelihood of their introduction into the UK

borers such as the bronze birch borer and the two lined chestnut borer. Biology:

Adults generally emerge from

infested wood in June and early July and feed on leaves of ash where they create notches in the leaf margins.

Adults mate and females

lay up to 90 eggs in the bark crevices in stems and branches.

Eggs hatch within 10

days and the first instar larvae bores through

to UK and Irish Trees and Ireland as well as discussing strategies that could play an important role in their management. Emerald Ash Borer (EAB) EAB (Agrilus planipennis) was first discovered in South-eastern Michigan in 2002 and has since spread throughout the Midwest and portions of the eastern United States. EAB is native to Asia including China, Japan, Russia and Korea. EAB was probably introduced on pallets or wood that was used to stabilize heavy cargo.

EAB attacks all ash species

native to the Midwest and is known to infest certain elms and walnuts within its native range in Asia. EAB larvae feed in the outer sapwood of ash trees and can rapidly girdle (ring bark) stems and branches. Trees often die within one-to-three years following the initial attack. Identification:

Adult beetles are emerald

green and approximately 1.25 cm long. Larvae are segmented flat worms that can reach 2.5 cm in length. EAB has a similar appearance and life cycle to other Agrilus

(Continued on page 30)

early summer leaving “D” shaped emergence

(Continued from page 29)

holes that are visible in bark of infested stems and branches. One generation year

occurs

and

adults

each are

capable of flying at least a half mile from the point of emergence. Long distance movement of EAB has been attributed to transport of infested wood and nursery stock. Management: treatments

are

EAB most

effective when applied on a preventative basis i.e. the bark into the sapwood. Larvae create “S” shaped feeding galleries that wind through the cambial area of the branches and stems. Larvae complete development in the autumn and overwinter as pre-pupae in chambers in the sapwood. Pupation occurs in early spring and adults emerge in late spring through

Susceptible Species

before a tree has been damaged. The most cost effective treatment is

soil

applied

systemic

insecticide

containing imidacloprid which acts as a neurotoxin.

This treatment is injected into

the root zone of a tree where it is absorbed and translocated to the stem and branches.

EAB

ALB

Ash, Elm and Walnut

Maple, Horse chestnut, Birch, Willow, Ash, Poplar and Elm

Symptoms

Notches on leaf margins, Woodpecker Leaf notching, Exit holes activity

Emergence time

June and July (USA)

June to October (USA)

Emergence hole

D shaped

>1cm diameter, may ooze sap, frass visible

Dispersal from hole

> 1/2 mile

Tend to remain on tree

Gallery shape

S shaped feeding Galleries, packed

meandering galleries, packed with frass

with frass

Larvae

that

bore

into

the

xylem

are

controlled by this insecticide. Imidacloprid is fully registered in the UK for the control of chewing and sap sucking insects. However, under UK pesticide guidelines imidacloprid can only be applied in February-March and October-November.

EAB

does

become

prevalent in the UK then imidacloprid will prove a useful management option.

approval for this insecticide to be used may be warranted. Further

management

strategies

include

heavily infested trees should be removed and destroyed by chipping, burial, or burning. Wood

should

not

stored

nor

transported from areas known to be infested by EAB. Good arboricultural practice to maintain the health of ash trees to include

Within the US, stem injection of another

pruning, fertilisation, mulching and irrigation

insecticide known as emamectin benzoate is

during dry periods will reduce stress and

usually effective in controlling EAB infestation

improve the tolerance of trees to EAB attack.

of trees in the initial stages of attack. Stem injection is then usually followed by soil

Asian Longhorned Beetle (ALB)

application of imidacloprid to prevent re-

Asian

infestation. At present however, emamectin

destructive pest of maple although other

benzoate is not registered for use in the UK.

deciduous trees such as horse chestnut,

longhorned

beetle

(ALB)

If EAB does become prevalent within UK landscapes then consideration of off label

(Continued on page 32)

alternating black and white stripes. Larvae

(Continued from page 31)

can grow to more than 5 cm in length and birch, willow, ash, poplar and elm can also be attacked. ALB was introduced into the US from China on untreated wood products. This pest was first discovered in the United States in Brooklyn in 1996 and later discovered in New Jersey, Chicago, and, most recently, in Maine. ALB was confirmed in the Paddock Wood

area

Maidstone

Kent

government scientists in March 2012. ALB larvae bore into stems and branches of host trees

creating

interrupt

water

galleries and

(tunnels)

nutrient

that

transport

resulting in dieback and decline of the tree. Galleries can be so extensive that branches can become structurally unsound and prone to failure.

feed within the wood of stems and branches. Biology: Adults emerge from stems and branches in spring through early autumn. Emergence holes can be more than 1 cm in diameter and may ooze sap. Sawdust (frass) may be visible near the emergence wounds. Adults are not strong fliers and tend to

remain on or near the host from which they emerged

where

Following

mating,

they

feed

females

on chew

leaves. 5

depressions in the bark where they deposit eggs. Each female can lay up to 120 eggs. Eggs hatch soon after deposition and larvae bore into the wood on stems and branches. Larvae feed in the outer sapwood near the

Identification: Adults are shiny black with

bark surface when they are young, but tunnel

white spots, 2-4 cm long with antennae that

deeper into sound wood as they grow larger.

are longer than the body. Antennae have

Galleries created by the larvae interrupt water

and nutrient transport and are responsible

supplement

for dieback, decline and death of the tree.

systemic insecticide treatments. These spray

Larvae complete development the following

treatments control adult beetles that feed on

spring and pupate within the galleries and

leaves, larvae that hatch from eggs on bark

emerge as adults. One generation occurs per

surfaces and deter females from creating egg

year.

laying wounds. For optimal protection, two

Management:

Within the US ALB is a

regulated pest that requires establishment of quarantine

the

Department

Agriculture when infested trees are detected. Surveys are conducted to define the extent of the infestation, and infested trees are then removed and destroyed. Infested trees are considered those that have emergence holes and/or egg laying wounds. Buffer zones are usually created whereby non-infested host trees in the vicinity of infested ones are removed or chemically treated in an attempt to eradicate the pest and reduce the risk of spread. In addition â&#x20AC;&#x153;regulated articlesâ&#x20AC;? cannot

the

protection

provided

spray treatments would be recommended per year to take place in May/June and July/ August.

Within

the

pyrethroid

deltamethrin is a broad spectrum synthetic insecticide fully registered for amenity trees that is effective against insects following ingestion and/or direct contact. Deltamethrin persistence on foliage can last for 6-10 weeks. Pyrethroids such as deltamethrin interfere

with

normal

production

and

conduction of nerve signals in the insect nervous system. Deltamethrin in combination with imidacloprid would prove a very useful insecticide to aid in the control of ALB.

be removed from the quarantine areas.

Asian Longhorned Beetle and Emerald Ash

Regulated articles include firewood from

Borer Distinguishing features.

deciduous tree species, living and dead plant material from all preferred or occasional hosts, live plants to include nursery stock, logs, branches, roots and plant debris larger than 1.25cm in diameter. Similar to the US, within the UK potential host trees within an extended

infested

zone

area

are

being

mapped and the size, species and numbers of trees felled and incinerated is recorded.

Although these two beetles vary greatly in appearance, it is often usual to see the individual beetles on, for example, a single visit to a site. It is important therefore to identify the symptoms and damage caused by borers in order to identify and control the damage. The table below lists a number of these borers distinguishing features.

Similar to the control outlined for EAB systemic insecticides containing imidacloprid should be applied to prevent larvae from infesting trees. In addition to imidacloprid, pyrethroid insecticides applied to the stem, branches and leaves of host trees will

Dr Glynn Percival Bartlett UK

LTOA elect new chairman The London Tree Officers Association (LTOA) has elected Richard Edwards, tree & woodland officer for the London Borough of Croydon, as the new chair of its executive committee. Edwards said: "I am hoping to concentrate on maximising the benefits that LTOA membership can bring to grass-roots tree officers to aid them in their day-to-day activities, whether that be through seminars, working groups or publications. "I am a great believer in using the exchange of information and knowledge to support tree officers and develop their skills, and we will be working hard over the coming months to achieve this." The new Vice Chair is John Parker, arboriculture & landscape manager for Transport for London (Central area). Full details of the new committee are on the LTOA website. Www.ltoa.org

Openness of Local Government Bodies Regulations 2014 in Force 31st July 2014

Originally posted in the MTOA on-line members forum on 31/07/2014 by Ruth Rose of Stratford Borough council. The Openness of Local Government Bodies Regulations 2014 comes into force on 31st July 2014. They were only laid in Parliament on July 3rd, so no time at all before they come into force. I only found out about them yesterday (30th July 2014). The Regulations deal with the filming and recording of meetings and publication requirements for decisions made by Local Authority Officers. It would appear that any decisions delegated to officers that:



grants a permission or license



affects the rights of an individual



awards a contract, or



incurs expenditure which materially affects the local authorities financial position, will need to be recorded. The officer making the decision will need to produce a written record as soon as practical after taking the decision which must cover:



the date the decision was taken



what the decision was and the reasons for the decision



details of alternative options considered and why they were rejected



(in the case of express delegations) any member who declared a conflict of interest



any background papers they have used (non-published which has been materially relied upon in writing a report) The decision must be made available for inspection by public:



at the offices of the relevant local government body



on the website of the relevant local government body



by other such means that the relevant local government body considers appropriate Whilst I’m not concerned about TPO applications for consent, Section 211 Notices and Hedgerow Removal Notices as these would all be web-enabled and available to the public, there are other areas of work which require decisions and are not currently publicised:



TPO Replacement Planting Notices (S206)



Replacement Hedgerow Notices



Work under the Miscellaneous Provisions Act 1976



Requests for TPO’s to be served



Dealing with dead/dangerous trees



High Hedge Remedial works Notices

The list could go on. I thought I would highlight this to other LA officers as the deadline is imminent. I’ve not given consideration to how I’m going to record this information yet, but there are a series of meetings at my authority next week to see how to progress this. If any of you are aware of these Regulations. and have already put in place measures then I’m sure we all would appreciate some help on this. If you are not aware of them, then you are now! Please see the forum for updates here: Of reply directly to Ruth by clicking on her name below. R Rose Stratford Borough council

In the last article we looked at what constitutes the ‘Urban Forest’, concluding that one of the simplest ways to start assessing this resource is to look at Canopy Cover. In this article we will briefly explore what canopy cover means, the methods by which it can be assessed, and its uses. Further reading is signposted within the article but also feel free to contact the author with any queries at: Kenton@treeconomics.co.uk

Kenton Rogers Introduction Quantifying canopy cover has been identified by many authors to be one of the first steps in the management of the urban forest. For example, in James Schwab’s book ‘Planning the Urban Forest’, it states: ”The first step in reincorporating green infrastructure into a community’s planning framework is to measure urban forest canopy and set canopy goals”. Canopy cover, which is often also referred to as tree canopy cover and urban canopy cover, can be defined as the area of leaves, branches, and stems of trees covering the ground when viewed from above. Canopy Cover is a two dimensional metric, indicating the spread of canopy cover across an area. It is not to be confused with Leaf Area Index (LAI), which is a measure of the number of layers of leaves per unit area of ground (although Canopy Cover studies can be used to estimate LAI). Assessing canopy cover is popular because it is relatively simple to determine from a variety of means and it can be calculated at relatively little expense.

Measuring canopy cover has helped city planners, urban foresters, mayors and communities see trees and forests in a new way, focusing attention on green infrastructure as a key component of community planning, sustainability and resilience. It is an easy-to-understand concept that is useful in communicating messages about our urban forests with both the public and policy makers. How can Canopy Cover be measured? There are 3 main methods to obtain canopy cover data; 1. Field Work Surveys This method requires surveyors to visit a number of sample plots and take direct measurements on the trees within them. The average Canopy Cover, along with its variability, can then be estimated for the entire area. The advantage of this method is that you can also collect additional data on tree species and tree size not normally available using the other methods. It is probably the most labour intensive, although it could be incorporated into an existing survey regime such as tree health and and tree safety inspections.

2. Random Point Method (using Aerial Photography or other remotely sensed data) This method involves desk study of aerial imagery using a Geographical Information System (GIS). The method can be used to

quantify tree cover by counting the relative number of random points in each area which are covered by trees. This is the principal used by i-Tree Canopy. Its quick, cheap and requires minimal training but only provides information on overall canopy at the chosen scale. It is however a very good starting point to start looking at canopy cover. 3. Area Method

species, height and even numbers of trees when several individuals form a closed canopy. In some cases, trees can also be ‘hidden’ within the shadows of large buildings and a small proportion of shrubs may also be mistaken for trees.

How do the methods compare? There are few examples in the literature on directly comparing the methods described, although a study carried out by the City of Toronto (2008) used the 3 different methods which are reproduced in Table 1 below. The study concluded that [for its purposes] point sampling from aerial imagery was the most cost effective, whilst also recognising that [in this instance] it provided a conservative estimate compared to the other methods.

This method involves using aerial imagery and digital mapping to determine the tree canopies using Method Result (% tree canopy) GIS, to calculate USDA Forest Service - automated classification of leaf on 2007 satellite 28% tree cover for imagery given areas. This City of Toronto - 2008 i-Tree Eco study, ocular estimate of canopy cover 24% method can (407 plots) provide much finer USDA Forest Service - 9,998 point sample, manual interpretation of 2005 19.9% detail at any leaf-off aerial photos chosen scale but USDA Forest Service - 9,998 point sample, manual interpretation of 1999 20.6% depending on leaf-off aerial photos resolution the City of Toronto Urban Forestry - small sample size, digitized manually from 17.5% aerial imagery can 2002 aerial photos with area estimates by land use be very expensive University of Toronto - 2000 UFORE study, ocular estimates of canopy 20.5% to obtain. Another cover in 211 sample plots disadvantage is Table 1: Comparison of different methods for assessing canopy cover in Tothat it is still very ronto. Source: Every Tree Counts - a portrait of Toronto’s urban forest difficult to to get (2008). any information about other aspects of the trees such as the (Continued on page 38)

Fig 1: Australia’s Urban tree canopy cover at a glance. Source: Where are all the trees? (Continued from page 37)

The Toronto experience shows quite a high variability in the different methods over a period of 8 years, although this does not necessarily mean that any one method is incorrect, just that it needs to be interpreted with consideration for the expected statistical accuracy. What can Tree Canopy Cover tell us? At a very basic level Canopy Cover provides a percentage figure of the amount of tree cover in a given area and could also indicate how much room there may be to plant more trees. However, do not be fooled! even this basic measurement can be implemented in a variety of different ways, with varying levels of sophistication and complexity. Depending on how a project is set up Canopy Cover can be assessed at the individual property level, by ward or by borough,

through to the city, county or even country scale. Take for example the recent canopy cover league table completed by University of Technology, Sydney and 2020 Vision in Australia1. They are using the results of a country wide canopy survey (see fig 1) to benchmark and provide a baseline for their aspirations to increase their urban greenspace by 20% by 2020. This example illustrates which cities have good canopy cover, those which are dominated by ‘hard’ surfaces and grey infrastructure and those where opportunities exist to increase canopy cover. In many international canopy cover studies the mapping of existing tree cover levels and distribution has been used to set future targets. This is regarded as good practice by the US Conference of Mayors, the US Department of Agriculture Forest Service, and

many non-for-profit organisations including the Arbor Day Foundation (US-based), American Forest (USbased), the National Urban Forest Association (Australia-based) and the Trees and Design Action Group (UK-based). In the US, American Forests offers some general guidelines for canopy goals based on climate conditions and land-use categories. Although city wide figures are helpful, especially in country wide projects, tree cover is not uniform fig 3 An example of infill from Perth, Australia with an obvious reduction in canopy cover. However, with canopy covthroughout a city. Generally canopy er assessed at the parcel level, city planners can now seek to ensure that canopy cover levels are maintained or enhanced as a planning condition. cover will change in relation to land-use, geography and other social and political factors. Illustrating this point are two separate studies carried out in the US2 and the UK3. These have highlighted a trend where most of the canopy cover in urban areas is provided by residential areas, and also, that it is often the most deprived areas which have the least tree cover. A land use approach was adopted by Natural Resources Wales, who have recently completed a canopy cover survey to look at the tree cover in all of its urban areas4.

Fig 2: Canopy Cover by Ward for Swansea Wales. Source: Tree Cover in Walesâ&#x20AC;&#x2122; Towns and Cities 2014 ÂŠ Natural Resources Wales

They have compared their tree cover for different land uses within a city as well as comparing overall canopy figures with other cities throughout the world. The results can be readily used to (Continued on page 40)

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Fig 4: Tree cover and Urban Tree Canopy (UTC) potential at the parcel level. Image courtesy of J O Neil-Dunne, University of Vermont. make comparisons between different cities, or between different parts of the same city (See fig 2). A study at this scale can help to target tree planting where tree cover is lower, delivering benefits to the areas that most need it. The University of Vermont Spatial Analytics Laboratory have analysed the canopy cover at the parcel level for a growing number of cities in Virginia. At this scale it is possible to use the canopy mapping as a tool for maintaining or enhancing tree cover during development by requiring levels of canopy cover to be maintained or enhanced as a planning condition See Fig 3 overleaf. This is a particularly important issue for many cities as the pace of development accelerates to keep up with the demand of evermore people moving into urban areas. Increasing demand for space often means that tree canopy is removed to make way for building and development, often on â&#x20AC;&#x2DC;infillâ&#x20AC;&#x2122; (see fig 4). Yet it is the canopy cover which makes our towns and cities better places to live, providing important ecosystem services like urban heat island reduction and air pollution filtration. Therefore measuring

canopy cover is crucial for establishing a baseline from which to monitor future progress. Repeated measurements of Canopy Cover, for instance using historical aerial photographs or repeated surveys, can highlight changes in tree cover over time and space and there have been studies done in Wales, England (already cited) and the US5. Although some cities and towns showed an increase in canopy cover, the general trend has been a gradual reduction in the area of canopy, most probably due to the reasons described above. Another way in which canopy cover can be used is to look at correlations between tree cover and environmental performance of an urban area. Canopy cover measurements can be used with other data such as crime rates, climate data or health and well being statistics to provide insight into how urban trees affect- and are affected by - various social and climatic factors. Work in Manchester, UK6 has assessed canopy cover at the ward level and has compared this with statistics on Acute Respiratory Disease and Mental Health. It found a positive correlation between tree cover and reduced rates of hospital admissions for these conditions. These relations are important and the Clean Air Act in the US recognises tree canopy management plans as part of State air quality management plans, based on the link between trees, ambient temperature and ozone levels. Conclusions Hopefully youâ&#x20AC;&#x2122;ve been given an insight into how assessing canopy cover can be used in a variety of ways for urban forest management. We really have only just scratched the surface of this fascinating subject. Thanks to

advances in Geographical Information Systems, the measurement of tree benefits and the sciences of Arboriculture and Forestry there has never been a better time to start using these tools to make our towns and cities better places to live by supporting decisions to get the right the right tree in the right place.

Trees in Towns II. Dept for Communities and Local Government, London 3

Tree Cover in Walesâ&#x20AC;&#x2122; Towns and Cities Available at: http:// naturalresourceswales.gov.uk/our-work/ community-link-working-together-workingwith-you/tree-cover-in-wales-towns-andcities/?lang=en#.U9Yn9l5IlQ9 4

Nowak and Greenfield (2012). Available at: http://www.itreetools.org/Canopy/ resources/ Tree_and_Impervious_Cover_change_in_US_Ci ties_Nowak_Greenfield.pdf 5

References Where are all the trees? Available at: http://202020vision.com.au/research 1

Connecting People with Ecosystems in the 21st Century: An Assessment of our Nations Urban Forests. USDA Forest Service 2

Manchester Tree Audit 2. Available at: http://www.redroseforest.co.uk/web/ images/stories/downloads/Valuing% 20Manchester's%20Trees%20-%20Tree% 6

Google can serve as "entry-level GIS for urban tree managers" Google's Fusion Tables web application can serve as a low-cost multi-user geographic information system (GIS) for urban forest managers, Canadian researchers have concluded. "Google Fusion Tables provide cloudbased computing services for data management and easy user collaboration through the Google Maps interface," the team from Toronto's Ryerson University said. "Fusion Tables are oriented toward smaller organizations that previously were unable to publish data online due to limitations of database knowledge and high cost of start-up."

Image: CityTrees.c

An interactive web-based mapping platform, the CityTrees.ca project, tested the technology's ability to map trees on the university's campus, while query interface enabled users to narrow down the tree population by species, diameter, height, and location.

"We found that Fusion Tables performed well as a storage medium for our campus tree data, which could easily be explored through our creation of a JavaScript- enabled query tool," they concluded - describing their efforts as "a roadmap for small to medium-sized urban forestry organizations seeking to create interactive mapping applications".

Over £25million of damage has been caused to new homes by trees over the last six years, according to figures released by NHBC. The UK’s leading warranty provider and standard setting body for new build homes is so concerned by the scale of the claims that it has today issued guidance to home owners advising them of the best practice when planting trees close to their homes. The figures show that over £25million of claims were made by owners of new homes for damage to their property caused by trees between 2008 and 2013. Last year alone, NHBC paid out nearly £4million in claims following structural damage caused by trees. As summer approaches, an NHBC guide offers practical advice to anyone thinking about planting new trees and shrubs or cutting back existing ones. Tips for homeowners include how to calculate a suitable planting distance away from houses and where to go to check if the tree is protected. Richard Tamayo, NHBC’s Commercial Director, says: “New greenery can create a more attractive garden as well as provide privacy and can help in reducing noise from a busy road. But roots and branches can also cause expensive damage to homes as our figures show. ‘When an established tree is removed or a new one is added, it can affect the moisture content of the surrounding soil. In clay soils, this can cause swelling of the ground or shrinkage. This movement can potentially result in damage to the house foundations due to subsidence or heave, particularly where the foundations have not been designed with trees in mind. ‘If the tree was added or removed before the house was sold by the builder, NHBC’s Buildmark warranty may provide protection. However, if the tree was removed or planted by the homeowner subsequently NHBC cannot provide cover and the household insurance may also not cover the damage. ‘This is an ideal time of year to start planting trees and shrubs ahead of those lazy summer days in the garden. But anyone thinking about planting new trees or shrubs should spare a thought for their home and their neighbours by getting an expert opinion before planting.’

Xypoxylon fragiforme - Beech woodwart

There’s plenty of information out there on the most common 20 or so fungi we see regularly on trees in the UK, so it makes sense to take a look at something we might not be so familiar with. This edition’s fungus of note is Beech woodwart, Xypoxylon fragiforme. Proper identification is less important than for species such as Ganoderma, but it is interesting and useful nevertheless. X. fragiforme is a relatively common fungus and is often found in clusters on deadwood on forest floors. It is almost exclusive to beech, although similar related species can be found on birch, alder and hazel. The fruiting bodies are small, usually only around 5mm wide and are dimpled over the surface, giving them a ‘warty’ appearance. If you’re lucky enough to see fresh ones, they will be a light salmon-pink shade, before they turn rusty brown and then charcoal-black. Superficially, H. fragiforme could be confused with species of Nectria fungi, although they are easy to tell apart. Crack one of the fruiting bodies open and you should see a layer of spore sacs just below

the surface, which surrounds a charcoallike layer in the centre. Crack open a species of Nectria and it will pretty much disintegrate. Whereas Nectria is mildly parasitic and linked to canker formation in many species, H. fragiforme is exclusively saprotrophic and so can be used as a good indicator of dead wood in limbs of beech. It will also remain on wood for months, much like miniature versions of King Alfred’s cakes. Hypoxylon is reported to exist latently within the sapwood in healthy trees, and it is only when limbs die back and moisture levels are greatly reduced, that mycelium will begin to colonise branches. White rot is

the result, so branches will snap like a piece of cheap celery. This is not a fungus that can be managed in any way and regardless of whether it is Xylaria, or Nectria, the wood is almost guaranteed to be dead. Either way itâ&#x20AC;&#x2122;s an interesting fungus and one to look out for. Enjoy! Chris Parker

Tweed Back in the murky days of old when craggy, tweed jacketed foresters ruled the Earth (or at least their domains within the Forestry Commission) I was a lowly pre-college forestry student. Happily learning my craft in Thetford Forest and soaking up all I could about trees. One day my compatriots and I – there were four in our jolly band- were dispatched post haste to Lynford Arboretum to deal with something extremely important. Sadly, the intervening years and a predilection for strong cider prevent me disclosing what this something was… However, the arboretum was a revelation and I was to return there many times to be among the specimen trees. In one quiet corner and set against a blackout of Corsican Pine plantation was a Birch. It was autumn and the trees were beginning to take

colour but this Birch stood out like a flame! Clear yellow from top to bottom with nary a leaf having fallen prey to the wind. It was superb. Wandering over, I read the tag: ‘Betula lutea’ E.N. America’. And so began a mostly unrequited love affair… The Net There have been brief meetings in other arboreta, dalliances in nurseries and much longing from afar in books and on the internet. Sadly I never managed to possess the object of my affection. Despite having trawled around the nursery trade I was unable to source a specimen. Nurserymen were unconvinced about its marketing potential or it’s tolerance of nursery

conditions. However the specimens I’d seen convinced me that the search was worth the candle so I carried on.

Now, Birch seeds are tiny so half a kilo is a lot of seed. Sowing millions of tiny Birch seed by hand is beyond the pale even for a tree spotter like me. No, what I needed was a friendly nursery to grow these properly and one was duly located and charged with the job. This brings us to the present time where I currently have a small quantity of Betula lutea being grown on in cells. Time will tell whether these succeed and grow into my arbormuse. Character (istics)

During the 2012 Ride for Research we visited Birmingham Botanic Gardens and lo and behold a Yellow Birch! This time labelled as Betula alleghaniensis which is a synonym. After a ‘bit of a tiff’ with Mick Boddy over whether this tree was otherwise known as B. lutea (cheers Mick!) I got to ask Simon Gulliver (curator) where they had had their specimen from. ‘From seed, I think from Kew’ was the reply. Sadly Kew couldn’t help either so I was back to distant longing.

For those of you still interested (bear with me dear reader) I have listed the characteristics of the tree below. My purpose with this piece is really to raise the profile of the tree and to increase its distribution in amenity plantings. It deserves to be at least as popular as the now seemingly ubiquitous Betula nigra or Betula utilis. If you do plant Yellow Birch –you really should you knowand you spot an odd looking tall chap gazing lovingly at it then don’t call the nice gentlemen in the white coats. It’s likely to be me and as anyone on the MTOA board will attest: I’m quite harmless..

Fate By chance an old friend contacted me out of the blue and in conversation revealed that they worked as a seed buyer for a major plant company. Light bulb moment! They eventually found some seed at which juncture I bought half a kilo…

From my own perspective the tree has several useful amenity attributes.

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Bark colour and texture is great with a good bit of variability between trees but generally yellow-bronze. Autumn colour as described in the article is excellent. It is unclear whether this performance is universal on all soil types or whether it is enhanced by acid soils. Leaf shape is pleasing with long, ribbed leaves (think of a long Hornbeam leaf) so don’t instantly look Birch-like.

4-9 cm broad, with a finely serrated margin. The flowers are wind-pollinated catkins 3-6 cm long, the male catkins pendulous, the female catkins erect. The fruit, mature in fall, is composed of numerous tiny winged seeds packed between the catkin bracts. Betula alleghaniensis is the provincial tree of Quebec, where it is commonly called merisier, a name which in France is used for the wild cherry.

Yellow Birch bark

The wood of Betula alleghaniensis is extensively used for flooring, cabinetry and toothpicks. Most wood sold as birch in North America is from this tree. Several species of Lepidoptera use the species as a food plant for their caterpillars. See the list of Lepidoptera that feed on birches.

The below is copied from Wikipedia but gives a nice summary of the tree. Betula alleghaniensis (Yellow Birch), is a species of birch native to eastern North America, from Newfoundland to Nova Scotia, New Brunswick, southern Quebec and Ontario, and the southeast corner of Manitoba in Canada, west to Minnesota, and south in the Appalachian Mountains to northern Georgia. It is a medium-sized deciduous tree reaching 20 m tall (exceptionally to 30 m) with a trunk up to 80 cm diameter. The bark is smooth, yellow-bronze, flaking in fine horizontal strips, and often with small black marks and scars. The twigs, when scraped, have a slight scent of oil of wintergreen, though not as strongly so as the related Sweet Birch. The leaves are alternate, ovate, 6-12 cm long and

The name "yellow birch" reflects the color of the tree's bark.[1]

From October 2014 I should have a number of these trees available as cell grown. If you’re interested in them either for nursery trials, domestic plantings or amenity plantings then please get in touch by emailing me at lepus66@hotmail.com I’ll only be covering costs of seed and production so they’re likely to be £1.50£2.00 each. Gareth Hare Lichfield DC

Fanfare to the common man Richard Nicholson The fog descended as I drove through the half-light south of Marlborough, reflecting the beam from the headlights back at me. I nosed the car cautiously along the road through Savernake Forest excited by what I was going to see. The indistinct woods on either side gave way at road junctions and the edges had a disturbing softness as oncoming cars approached and we both tried to gauge the width of the road.

The Big Belly Oak came looming out of the fog like an Ent in a hurry, catching me unawares this evening. The Big Belly is an Ancient Oak standing just beside the road on the left hand side. Actually, letâ&#x20AC;&#x2122;s be honest, Belly was probably here long before the road. Ancient trees are wonderful. Ancient trees make you gasp. Even though I know where Big Belly is I am always surprised and overawed by the sheer size of him. He just sits there as big as a watch tower, the ancient guardian of the forest. I pulled over and walked back through the fog. If Iâ&#x20AC;&#x2122;m going to get run over, this would be a great place for it to happen. Big Belly is squat, bulbous, rooted to the ground, immovable. My visit is so infinitesimal in his existence, but the effect he has on me I carry to this day. The scent of the forest, the absolute silence

broken only by the sound of drips where fog condensed on his long fingers, and dropped, disturbing the leaves on the ground. Because not only is Big Belly an Ancient tree, he is also a pollard. Centuries ago, when Big Belly wasnâ&#x20AC;&#x2122;t big nor had much of a belly, in fact when he was quite a slim almost willowy young thing, someone beheaded him. The act turned Big Belly from a forest tree with a useful life span on perhaps 150 years to a timber producing monster that is still growing, centuries later. This act was part of an industrial revolution that had been going on in in the green and verdant landscape for thousands of years. This was the start of intensive timber production from Big Belly and millions like him that not even the conifer monocultures of today can compete with. Because every so many years a

proportion of the regrowth, mainly small diameter branch wood was removed and every time Big Belly responded by producing more shoots which self-selected and grew into new branches ready for the process to be repeated. We cannot quantify how many hundreds of times Big Belly has been harvested. All that timber from just one tree. My fascination with pollards started when I first developed an interest in trees. Growing up within a stone’s throw of the Castle Park in Colchester, we used the Lime trees that grow in a line against the park wall as goal posts. They didn’t look like the other trees in the park; they had substantial trunks but compact, dense bushy canopies. One day we turned up to find a man up a ladder with a handsaw cutting all the branches off. We sat and watched (and shouted rude comments I seem to remember) until the man had removed and thrown to the ground the last branch. The tree stood there like a weathered monolith, not unlike some of the Roman ruins that give the park its name. Considering the hard time we had given him, the man from the Council was friendly enough and answered all our questions about not killing the tree, why all the branches were the same size, when would he have to do it again and would he play football with us now? Years later I became an arboriculturist but in all my years of climbing, I only got to pollard about half a dozen trees. The oldest record of the practice of pollarding I know of is contained in a manuscript dating from 1523 called The Arte of Husbandrye by one Fitzherbert: If a tree be heeded and used to be topped and cropped at everye xii or xvi years ende or thereabout it will beare moche more woode by process of tyme than if it were not cropped and muche more profyte to the owner.

Let hymme beginne at the nethermoste boughe first and with a light axe for an (one) hande to cut the boughe on bothe sydes a foote or two foote from the bodye of the tree. A specially cut it more on the nether syde than the over (upper) syde so that the boughe fall not straight down but turn on the syde and it shall not flawe (strip) nor breake no barke. And every boughe shall have a new head and beare mooche more woode. And by thy wylle without though must needs do it, heade him not when the wynde standeth in the north or in the easte, and beware that thou croppe him not in sappe tyme. Pollarding or ‘polling’ can be defined as ‘beheading or polling a maiden tree at 2-3m above the ground’. The timber produced was used for firewood, wood products like tool handles, and small diameter building timber. Most rural dwellings used small diameter timber for rafters. The rafters in our cottage which dates from 1680 are ash poles. I have no idea how many times the thatch has been renewed and the rafters replaced, but the last time it was done, probably in the 1920s, small diameter de-barked ash poles were used. I like to think that they came from some of the old Ash trees growing above the village, near the heath. Words like ‘lop’, ‘top’ and ‘brash’ describe the arisings. Brash was used for animal fodder, probably cut in the summer when in leaf and either fed directly to animals or stored for use as winter feed. Herdwick Sheep still browse on Ash fodder in hill farms in the Lake District. Holly was also used for fodder; there are good examples of holly pollards in Windsor Great Park remaining to this day. (Continued on page 54)

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Of course, Fitzherbert was writing for landowners, men of learning, those that were educated. Both Evelyn in the 1664 Sylva or a discourse of Forest trees and John Mortimer in his The Whole Art of Husbandry: Or, the Way of Managing and Improving of Land written in 1716, talk about planting trees for timber. Trees that would be high pruned by the removal of the small lower branches, producing clean stemmed trees desired by the Navy, industry and builders of great buildings. The common man had no use for these and had neither the tools nor the capability to deal with them. The common man probably didn’t plant many trees either. Those for whom common land provided their livelihood would stop grazing their animals in areas to allow the unending cycle of seed/ sapling/tree, the process we refer to as ‘natural regeneration’, to take place.

My view is that pollarding was the work of the common man. And he, by trial and error, managed to develop a harvesting cycle that not only didn’t kill the tree but that produced useable timber for his needs and fodder for his livestock. The mistakes, and there must have been plenty of those, have returned to the forest floor. We are walking on all the trees that were killed by too vigorous a pollarding regime and that decayed and returned to the soil. Common man discovered that age matters. We know now that a young tree, a maiden, has a balance of dynamic to static mass that will mean that it will have sufficient carbohydrate reserves to regrow. An older tree has more static mass, more wood laid down which is no longer functioning, than dynamic mass, the active functioning wood. Common man also regarded age as self-limiting because the older a tree is, the thicker is the trunk. In the

days of axes it was easier to behead a younger tree with a small girth than an older one with a larger girth. The landscape of pollard trees was a wood pasture, either a woodland where wood is permanently available, or a pasture with trees, which description depends on the density of the trees. This land use developed out of the pre-historic practice of depasturing cattle into woodlands when normal grazing became scarce. Obviously the long term grazing and browsing of cattle presented a serious problem by destroying the new trees which would eventually result in the wood declining. On the other hand, too many trees reduced the amount of herbage. The balance was struck with the help of pollarding, where timber and fodder can be produced beyond the reach of grazing cattle. It’s like coppicing on legs. The fact that the cattle would be browsing on the natural regeneration of the woodland floor is not an issue for the cattle owner who is growing a fodder crop 2-3m above ground. So what is the reason that centuries old pollards like The Big Belly Oak have survived to this day? Well it is partly accident and partly by design. Some like those in Hatfield Forest survived on land being retained as Common land, continually managed by pollarding and some survived by being incorporated into forests or chases (as in hunting land; think of the New Forest) and deer parks. We know this because of historical records. Roger Tavener, a Surveyor for the Court of Augmentations (a body set up to better control land and finances) provided condition reports on woodland throughout the country. In 1565 he recorded a visit to Meere Park in Wiltshire: the park has old oaks whereof 30 are timber, the rest ruinous and shells the number 600

These ruinous shells are almost certainly formerly pollard trees now no longer managed as such because the land is now in private ownership. He also described the use of pollards at a wood called Little Park in Essex: divers oaks, ashes and hornbeams commonly used to be shred for browse for the deer and there be also growing divers other oaks being timber and meet for pole and rail. and at Oakley Park, Shropshire: but the rest have been of old time lopped and topped and the lopps and tops thereof yearly to be taken will scarecely suffice for browse for the deer, and the said browsewood will scarecely suffice for the necessary firewood of the keeper there. Even in 1565 some of the old trees had lost vigour and were probably in a spiral of decline. In all likelihood, these would not have been cut down. What was the point? There was no value in the timber and the effort required using the basic saws and axes of the day was not an option. In the old days, as in most primitive societies today, people didn’t waste energy producing a product with no value simply to make the place look tidy. Tidy landscapes are a modern day phenomenon as land was developed for recreation rather than artisan production. There is a description of such an artisan landscape, and this is my favourite woodland quote ever, from the Reverend Francis Kilvert who visited Moccas Park in Hereford in 1876. Rev Kilvert was a diarist and recorder of rural life. In April 1876 he wrote: ‘we came…slipping, tearing and sliding through the oak and birch and fallow wood of which there seemed to be underfoot an accumulation of (Continued on page 56)

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several feet, the gathering ruin and decay probably of centuries. ‘I fear those grey old men of Moccas, those grey, gnarled, low-browed, knock-kneed, bowed, bent, huge, strange, long-armed, deformed, hunchbacked, and misshaped oak men that stand watching and waiting century after century biding God’s time with both feet in the grave and yet tiring down and seeing out generation after generation….No human hand set those oaks. They are ‘trees that the lord hath planted’. They look as if they had been at the beginning and making of the world and they will probably see its end’.

they were ignored and they fell apart. The canopy managed by the pollarding cycle had been kept small and the aged trunks were able to support it.

Two of our better known pollard landscapes are Epping Forest and Burnham Beeches. The Hornbeam pollards of Epping Forest were described by William Morris, the Victorian Designer as ‘very curious and characteristic wood as can be seen nowhere else’. The Essex Naturalist Series records that pollarding in Epping Forest almost certainly predates 1130 when the forest was established as a Royal Forest by Henry 1st. Commoners rights to lop continued in Epping Forest up until 1878 when they were extinguished by the Epping Forest Act. At this point the purpose of the forest changed and with it Victorian attitudes to the To bring the story up to the present day, deformed, misshapen but useful and some of the remaining medieval woods, productive pollards. Pollards were protected enclosures and common land were bought by the Act but public opinion, through the th out in the early 19 century and largely development of the forest as public open planted to oak. Alice Holt Forest in space, was now tending towards Hampshire is a prime example of this. Within ‘naturalness’ and ‘beauty’. In the absence of these woods planting grottos and waterfalls and would have taken place such like that are seen around the veteran in some of the “trees are now the pollard hulks, rather ‘natural’ gardens of preserve of the learned than them being the time, the best that removed. Where the could be achieved at and wise” Deer Removal Act of Epping was the 1851 was replacement of implemented, natural pollards with un-pruned, regeneration proceeded unencumbered by natural trees. Pollarding was industrial timber grazing pressure. And deep within the woods collection, yesterday’s product no longer the veteran pollards survived. But they required. It is prescient of the anti-conifer continued to grow, unmanaged, developing attitudes of the late 20th century and the massive crowns that they had never desire to return forests to native broadleaf produced before and that their supporting woodland. structures were not optimised to cope with. This hadn’t happened before; pollards had Burnham Beeches was bought by the always been managed on a cycle to produce Corporation of London showing remarkable a product, unless they were old, foresight in 1888, to stop a housing unproductive or too decrepit, in which case development and in order to keep the

woodland as a public open space for all to enjoy. Burnham Beeches contains both maiden trees and some fine old beech pollards. It is just 25 miles from London and is a mecca for anyone who likes their trees to be gnarled, misshapen and full of stories of man’s relationship with trees over the years. Gray wrote part of his Elegy here and the site was also visited by Mendelssohn, Shelley and Byron. Burnham Beeches is the focus of modern attempts to understand the lapsed pollard. The trees are now the preserve of the learned and wise and science has replaced trial and error. Having ceased to need their timber they have lapsed into senility and we have no history, no handed down knowledge of how to look after them. Ian Rotherham of Sheffield Hallam University refers to them as ‘retired veterans’ which is a delightful phrase neatly summing up their status. Perhaps we never did know how to look after them. We simply used them and there were

sufficient to provide for us. If they died or ceased to become productive, we moved to another one; there was always a new maiden to behead. Perhaps there never was a fallback position to restore them. Perhaps there is no art to re-discover, rather, we just need to develop ways of maintaining them. And like our commoners of old it is still important to create new ones for the future. As a Tree Officer, years ago I went to see a large Oak that a resident had growing in her back garden. In response to my comment about what a fantastic tree she had, she replied, “Oh it’s not mine dear, I just look after it while I live here”. We should adopt this notion: we do not own these monoliths, we are merely their stewards and we should look after them for future generations. Fortunately, as they grow old they have accrue other values, as niche habitats value as well as a scarcity value. This makes them important to a wider range of nature conservation groups who have engaged with them, can speak of them (Continued on page 58)

in their vocabulary and write eloquently of them. For me, they continue to have the ‘wow’ factor; their fantasy, almost mythical form dares you to harm them. Management challenges today include the need to make sure they remain relatively undangerous to the general public and to avoid the situation where they just gradually fall in to decay and disrepair. Of course, this is exactly what they have been doing for centuries but previously they could be left in peace, enjoying the woods to the end of their days, for centuries after they stopped working. The difference now is that there are fewer of them and they are more isolated than before. This is their scarcity value and this article is just one attempt to record and measure their importance in ways other than timber and produce value. And now I live just a few yards from another pollard, this time one with an important social significance. However the Tolpuddle Martyrs tree, a Sycamore is not a true pollard. It was pollarded on safety grounds in the 1980’s when it was taken over by the National Trust. Early photographs in the local museum show a magnificent open grown tree with a major secondary stem arising on the western side. A later photo shows that the top of the tree had snapped out and signs of vigorous regrowth. This noble tree, one of the 50 great trees of Britain that were dedicated by the Tree Council to mark the Queen’s Diamond Jubilee in 2002, was the tree beneath which the first Trades Union was founded. In 1833 a group of farmworkers formed a Union to protest about their wages and swore an oath that they would protect each other’s families if they fell on hard times. For this, in February 24th 1834, six of the men were arrested and jailed by the authorities who had been unnerved by the recent Swing Riots and who had an eye

on the Revolutionary events that were occurring in France. From Dorchester prison the six were transported to Van Dieman’s land, modern day Tasmania. The National Trust reckon that the tree, a magnificent ivyclad hollow carcass, is around 320 years old which means that it would have been a substantial 150 years old when the Martyrs met beneath it. It is a Sycamore, a common tree, often described by foresters as a weed species and one that common man rarely pollarded, Oak, Beech, Ash and Hornbeam being the timber of choice. But here it is, a proud sentinel in the middle of the village. The regrowth stretches upwards from the jail of ivy that encircles the hollow trunk, one limb for each of the Martyrs, George Loveless, Methodist preacher, and his brother James, Thomas and John Standfield, James Brine and James Hammett; a fanfare to the common man. I think that it is fitting that the tree most commonly associated with the common man should survive to this day as a pollard, as a monument to this practice, even if it is just a youngster compared to The Big Belly Oak, one of the truly grand old men of the 50 great trees of Britain club.

East Dorset District Council.

Trees are Worth It – arborists know it, foresters know it and there

In Lichfield, the City Council’s Open

is an increasing wave of professions that are beginning to

Spaces officer engaged with the

expound the virtues of trees too from Health, architects, town

town’s crier for added attention

planners and politicians. But what about the man, woman, child

grabbing. In Coventry the newly

on the street do they really know what trees do for us? Trees are

former Tree Warden Network and

Worth It, an initiative of the Midlands Trees and Design Action

canine companion (dog’s need trees

Group (TDAG Midlands) forum intended to bring this knowledge

too!) tagged a lime tree in Cuckoo

to a wider audience.

Lane which Treezilla estimates is

Citizen Science: Treezilla is a web site closely linked with citizen science through The Open University, The Open Science Laboratory and other organisations including Forest Research . It is a project to map trees especially in urban areas of Britain and it’s aim is to promote the ecosystem benefits of trees by giving them a monetary value so highlighting the importance of trees in our world and raising public awareness. Using the Treezilla website TDAG Midlands temporarily tied 'price tags' to prominent trees in towns and cities across the region. Through the local tree officer network and other TDAG contacts schools, tree wardens, individuals and businesses some 50 individual trees were tagged with the owners’ consent for one day only. Through Treezilla we all input the stem diameter, height and the species of our target tree and the software calculated the eco benefits provided by that individual tree in respect of greenhouse gas, water management, energy benefits and air quality as a monetary value. This was written on the label in waterproof ink!

A Soggy Success: The British climate is nothing if not unpredictable. But on the 4th June the day chosen for the Trees Are Worth It initiative it was horrendous! The drizzle across most on the country turned in to localised downpours on and off during the day and the whole thing could have been a complete flop had it not been for the hardiness of tree officers, tree wardens and dedicated people from Cirencester to Lichfield and the durability of the labels funded by the events’ three sponsors, the Arboricultural Association, Acorn Environmental Management Group and The Municipal Tree Officers Association.

worth £359.73 in stored CO2 alone. Across Stratford on Avon, Kineton, Rugeley, Cirencester businesses, charities, tree and forestry officers played their part. In Birmingham around St Philip’s cathedral 8 trees including a Camperdown Elm were tagged with a total monetary value for air pollutants absorbed of £124.16 equalling almost 14kgs of particulates per annum. Whilst in Cirencester a 17m beech was recorded with a value for storm water interception of £10.35 equating to some 6,211 litres per annum. Trees are Definitely Worth it! All who took part were disappointed only by the weather which limited the success of the day but there was very positive feedback from all participants. Visit www.treezilla.org for further information or www.tdag.org.uk to broaden your knowledge and appreciation for trees and register your interest for next year’s event. Julie Sadler Birmingham City Council

Has it a pulse? Tree Health day with the MTOA Welcome to another great MTOA Seminar. When and where? 24th September 2014 at the Birmingham Botanic Gardens, Westbourne Road, Edgbaston, Birmingham, B15 3TR. (click here for the map location The MTOA continue to bring you must attend seminars and this day will look at measuring tree health and tree health crisis preparedness, please see below for the speaker details. The itinerary for the day is; 9.00 – 9.30

Registration, tea and coffee

9.30 – 9.45

Moray Simpson (Wrexham council)– Introduction to the day & MTOA News.

9.45 – 10.00

A welcome from Rod Jones, Faculty Director for BMet College and our host for the day.

10.00 –11.15

Paul Davis (Hansatech Ltd.), “Chlorophyll Fluorescence for tree health assessment”.

11.15 – 11.30 Comfort Break 11.20 – 12.30 Julie Bolton (West Sussex County Council), “The Impacts of Large Scale Tree Loss” Please note this session will include a roundtable on preparing a strategy for sustainable tree cover. 12.30 – 13.30 Lunch 13.30 – 14.45 Outside field try-outs with the Arborcheck system 14.45 – 15.00 Comfort Break. 15.00 – 16.00 Jon Stokes (Tree Council), “Who is going to stop the decline”? 16.00 – 16.15 Summing Up & Final Questions.

All this for only £20, yes £20.00 for MTOA, CAS and ISA members. Non- members £65 (dependant on space availability), bookable in advance by contacting Jean McDermott on 0121 556 8302, enquiries@mtoa.co.uk

And finally. My third Edition back in the Editors role and things seem to be going well both for the magazine and the MTOA in general. We are represented and most “top tables” and attract attention from ICF, AA, DEFRA, Tree Council and such on a regular basis. As you can see from the advert on page 13 the Axe is getting distributed far and wide and in big numbers but this is hardly a surprise when you look at the strength of the contributing authors and the depth and variety of the articles, and this edition is probably the strongest so far in that respect, lets hope we can keep it up. However, and there’s usually a however, we don’t see many articles coming from within the ranks of the Municipal Arborists though, and advertising revenue is also non-existent so there is still some huge improvements to be made. The big issue on the horizon for many of us though is the constant onslaught of the LA financial cuts. Jobs seem to be disappearing at a rate that’s faster than the loss of Ash trees. You need to be represented at our September meeting where strategies to cope with the large scale loss of trees will be discussed in depth, and the thorny issue of who is going to manage this transition to a new species diversity matrix. It is a huge task, so prepare yourself.

Mac

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