Ian D. Rotherham

Trees remain in focus with extreme weather and local government cuts adding to the stresses

There is little doubt that extreme weather, in part at least related to climate change, is exacerbating stresses on an already vulnerable tree population. In the urban setting especially, trees are particularly under pressure. Local authorities, in many areas of Britain losing core funding to provide essential services and experienced operatives, further complicate this situation. Long-term underfunding of highway tree maintenance, for example, is leading to over-drastic action and an upwelling of public complaints – both for and against big trees. Indeed, in these times of climate change and of economic austerity, the important roles of local government and agency officers in working with local communities are at once curtailed or even abandoned and yet, at the same time, more important than ever. Extreme weather, which is becoming more frequent with climate change, combines with processes such as urbanisation and globalisation to make trees ever more prone to invasive plant diseases, with potentially catastrophic effects. Jon Heuch’s paper (2014) on Ash Dieback examines issues in relation to this in terms of the outbreak currently affecting Great Britain. In a very rounded examination of the issues, he considers aspects of the biological factors and those in relation to economics, politics and the media. There is one thing for sure, which is that this is only the latest troublesome infection to hit our tree populations; it is by no means the last. It seems likely that much of the spread has been due to spores carried by the wind, but even so, this must raise basic and fundamental questions about commercial tree production in Europe. A very narrow genetic base for stock, such as has been the case for Ash, combined with disease mobility and dense monocultures of stock, is, ecologically, a disaster waiting to happen. Furthermore, for a tree so easily grown from seed, such as Ash (which has the reproductive strategy of a “weed”), to be so widely grown for planting, seems rather pointless to those outside of commercial tree cultivation. Will we learn the lessons and be better prepared next time? See what Jon Heuch has to say. With tree population management, for conservation and in the case of an invasive pathogen, it is important to know what resource we have. In Britain, the Ancient Tree Forum has done sterling work to find and put big, old trees on the map. There is still much to do. Moore and Hughes (2014), present a fascinating account of the work of The National Trust of Australia (Victoria) in developing the Register of Significant Trees and now engaging a wider public through a downloadable app. Indeed, with rapidly changing IT usage and applications, and a desire to engage better, a younger generation, this must surely be a part of the way forwards. Knowing where trees are, recording this, and being able to access the information easily bring enormous potential benefits. In urban environments especially, approaches to “valuing” trees in relation to issues of conservation, of management, of removal and replacement have been featured in this journal on many occasions. It is helpful to have a perspective, which focuses on a particular species of tropical tree, as discussed by Ow et al. (2014) with Albizia saman as the case study. Worryingly, I am seeing many significant urban trees being felled without

The passing of a giant in the study of trees and woods – Oliver Rackham OBE (17 October 1939–12 February 2015)

It is with great sadness that the College announces the death of Professor Oliver Rackham OBEMA Ph.D. FBA, Botanist, Master of the College 2007 – 8, Fellow of the College 1964– 2007 and 2008–2010, Honorary Fellow 2008–2015 and Life Fellow 2010–2015, on 12 February 2015, aged 75 years. Professor Rackham collapsed during a dinner at Leckhampton on Tuesday evening (10 February); he was admitted to Addenbrookes Hospital immediately, and died at Papworth Hospital on the evening of Thursday, 12 February. The Dean of Chapel and some of his close friends were with him.

A–Z of tree terms: a companion to British arboriculture

this book is for everyone in Britain with a serious interest in trees. If you work with trees, the book will be a good companion, if you own trees, your responsibilities will be made easier to understand, and if you simply like trees the book will deepen your affection. If you are anxious about a tree-related problem, thinking of getting advice, need some tree work or have trees that are affected by a planning application, the book will be useful in practice. And if you are a serious student of trees you’d better know what one is.

Leading the way on issues of biological invasions, greenhouse gases, pest control and risk minimisation

In continuing to present leading edge research to a wide professional and academic audience, the Arboricultural Journal seeks to bring the most up-to-date contributions to its pages. In this issue, we present four major contributions to currently debated subjects of great importance to both the arboricultural industry and to the wider environment. Furthermore, as globalisation spreads disease and problems around the planet, these research contributions have potential significance to national economies too. Biological control of invasive and other problematic species continues to be a topic of huge interest and indeed, of potential commercial value. Ever since the landmark experiments of for example, the control of prickly pear in Australia by the Cactoblastis moth, ecologists have sought biological controls. Invasive trees and shrubs, introduced across the globe to new, suitable habitats, have the potential to cause major detrimental impacts and to be very difficult to manage or control. Biological controls often seek to impose the pressures of herbivory experienced in native habitats onto the same species now established in environments without adapted herbivores. One reason for aggressive invasion is simply the lifting of the burden of co-evolved herbivory and diseases. A potential solution is to find a suitable insect herbivore or plant disease, and to introduce it as a control agent to the new habitat. There are many complications and risks, and too much to describe here, save to say that a thorough investigation and testing must be done prior to any release programme. Khan, Sharma, Raman, Dhileepan, and Hodgkins (2014) present an account of work on the prickly acacia Vachellia nilotica ssp. indica a native of India and a Weed of National Significance in Australia. Dense populations of the acacia produce changes in native vegetation with ecological consequences and impacts on pasture and even hygiene problems in stock. Together with damage to wildlife habitats and soil degradation, this plant is an increasing problem in Australia. As with many such invasive species, simple physical control can be expensive and problematic, and so a biocontrol agent is an attractive proposition. Trials have identified a scale insect or lecanodiaspid, Anomalococcus indicus, a native to India, as a potential candidate control agent. Capable of having a major impact on the target tree, this arthropod offers great possibilities, which are reported here. In a world in which being environmentally friendly is increasingly associated with reduction of greenhouse gas (GHG) emissions, the use of energy-guzzling equipment and machinery may be both an embarrassment and a problem. For the arboricultural industry, which is intimately tied to trees and their management, and therefore considered “green”, this can be a serious issue in terms of perception and of fact. In this context, Luck, Lowe, Elphinstone, and Johnston (2014) have investigated the performance of the arboricultural industry in relation to GHG emissions. The public see tree maintenance professionals in urban areas relying heavily on equipment powered by fossil fuel. They are often removing trees that act as carbon sinks and are emitting carbon dioxide (CO2) during management activities. Based on these observations, it has been indicated that arboriculture makes

Urban trees, urban forests and valuing the contributions to landscape and living

As Clapp, Ryan, Harper, and Bloniarz (2014) assert, urban trees and forests are integral parts of the urban environment and the landscapes in which most of us live. Furthermore, the gross disruption of environments by urban dwelling means that the systems are inevitably, to some degree, out of balance. In addition, urban developments are major sources of air pollution and water pollution, contributing to the problems of pollution whilst at the same time depending heavily on the surrounding more natural systems to mitigate adverse impacts. In our increasingly urban society, using enormous amounts of resources for energy, urban areas contribute hugely to deforestation, degradation and global climate change. This paper takes an interesting look at a neglected issue, that of conifers and their contributions to ecosystem services in cities and towns. In addressing the issues, they question some assumptions of the benefits and dis-benefits of broadleaved versus conifers in urban street plantings. Percival and Sacre (2014) also consider a challenge for the planted urban trees, that of surviving beyond the nursery. In the face of high mortality rates, following planting out of ornamental trees into urban landscapes previous research has suggested that reserve carbohydrates in root tissue are crucial for successful post-planting survival. In this context, it seems that enhancing root carbohydrate status of ornamental trees during nursery growth has been neglected. High nitrogen, slow release fertiliser, sucrose and a plant growth regulator during nursery production significantly enhanced root carbohydrate of tree species tested. It is suggested that significantly enhanced root carbohydrate content during nursery production contributed to reduced transplant mortality and enhanced field performance (growth and vitality) over a 2-year, post-planting period. The findings will be of interest to those growing stock on for commercial planting and wishing to minimise losses on site. As Rodney Helliwell states (Helliwell, 2014),

Urban trees, ecosystem services and survival in a harsh world

A perennial problem with trees and people is that of big trees close to houses. Indeed, for new-build properties these are problems, which can and should be avoided, since not to do so may mean serious issues and costs in the future. When building new properties, it is simply best for them to set back a distance from any existing large trees. Helliwell (1983) provided useful guidance on this and suggested a distance approximating to the height of the tree to equate to the desired distance between tree and building. Of course, two further issues follow and relate to whether trees are newly planted or existing and in situ. The latter may be historically significant field boundary trees for example, and thus combine both the top level of ecosystem service provision and the heritage significance. These too, will also be most likely to have things such as bat roosts and breeding birds. A simple solution, but one not popular with cash-hungry developers, is to set building well back from such significant tree and thus avoid future difficulties. The same situation applies when placing a new-build property close to an ancient woodland edge. Very often developers and then planners are complicit in ignoring such practice and try to squeeze the pips out of the housing site. Then, once the new residents have settled in, they realise the significant issues of close proximity to mature trees or woods. By this time, it is too late and the scene is set for future problems, issues, conflicts, costs and potential hazards. Furthermore, cavalier use of heavy plant on a site often damages tree roots, boles and branches, again triggering future difficulties. With increasing pressures to build more and more houses, and local authorities shedding experienced officers, such problems are likely to get worse in the years to come. The role of good tree professionals will therefore become more important still. Andrew and Slater (2014) report on a survey to assess these matters in samples of UK residential areas, and in particular, consider resident perceptions and attitudes. There are serious implications of the findings for the delivery of ecosystem services in future urban areas. As well as the management of existing tree populations, the successful establishment of new tree stock is an important aspect of the urban forest. In this context, Percival and Schaffert (2014) consider the effects of water-retaining polymers on transplant survival of bare rooted silver birch (Betula pendula) and European beech (Fagus sylvatica). These two species are transplant-sensitive trees and the results of the research are highly significant in terms of recommendations for the use of polymerbased dips. Finally, this issue contains a view and vision of significant trees with a rather different perspective and time scale. In presenting a survey of trees in the Bible, Julian Evans (2013, 2014) brings a lifetime of experience and passion for trees to bear on a subject very close to his heart, and the reader may wish to refer to the book by Julian as reviewed in the Arboricultural Journal (36ð3ÞÞ: With lavish illustrations and a lively text, this volume brings to life aspects of tree history and even mythology that we rarely consider. The paper may whet your appetite.

Managing veterans for future conservation

This issue is the first of an especially themed series on matters of recognition, conservation and management of ancient and veteran trees. For tree managers, big, old trees can be particularly problematic, be they urban, urban fringe or rural. Management is fraught with issues of impacts, liabilities and more, and yet these trees that we possess are the most valuable and irreplaceable. In some cases, such trees may be formally planted specimens in important historic landscapes, in which case-specific issues relating to landscape origins and authenticity are raised. However, many of these trees are actually sometime worked or working trees, what I call “retired veterans” (see Rotherham, 2012, 2013a, 2013b). As papers by both Pankhurst (based on practical experience in Cumbria; Pankhurst, 2013) and Read et al. (from research and practice across Europe; Read, Dagley, Eloseguic, Siciliad, &Wheater, 2013) show, the abandonment of traditional or customary practice can present difficulties for conservation.

Climate, extreme weather and storms keep trees in focus

Recent storms, both in the UK and around the world, have taken their toll on trees and on people and property. Now, with over half the global population in towns and cities, trees play increasingly important roles in climate proofing. However, trees in densely populated cities pose problems too, and combined with extreme weather events can present serious risks. It is in this arena of trees and benefit, and trees and risk that many arboricultural professionals operate. Research to address these issues becomes ever more important. Understanding the ways in which trees function, and how best to assess or evaluate condition and behaviour, is hugely important but potentially complex. It is in this context that David Lonsdale (Lonsdale, 2013) presents his paper on tree functional units. This review of tree development and behaviour is a very significant and helpful step to enable practitioners to understand better the ways in which trees grow and their component parts interact. This insight then becomes important in guiding essential tree management. In urban situations, the impacts of trees on light are complicated and often contentious. Trees in woodlands too affect light in both quantity and quality; and they themselves are influenced by light regimes and availability. However, the assessment and measurement of light itself are problematic and frequently misunderstood. We therefore welcome this paper from Rodney Helliwell (Helliwell, 2013) as a contribution to clarify the issues and provide useful insight into light and trees, pertinent to both arboriculturist and forester. However, trees are not just individuals but also exist in landscapes, both rural and urban. The urban forest is a term used to describe the collective populations of trees in a town or city, though in truth, this mixes both the “urban” forest and the “urbanised” forest as people encroach into wooded areas. Gumbi, Sibandaa, Machererab, Moyob, and Kupikac (2013) have researched the impacts and issues for trees and woods in Bulawayo over a 20-year period from 1990 to 2010. This study shows the changing tree cover and the drivers of these changes. The woods provide essential resources for local people, but unless managed sustainably they become exhausted and degraded. This paper highlights some of the challenges ahead.

The art of creative pruning: inventive ideas for training and shaping trees and shrubs

Deadwood is a vital component of a properly functioning forest ecosystem. It plays an important role in sustaining biodiversity and in delivering ecosystem services such as soil formation and nutrient cycling. In the UK, up to a fifth of woodland species depend on dead or dying trees for all or part of their life cycle, and many of these species are rare or threatened. This practice guide has been written for the owners and managers of forests and woodlands who want to increase the value of their woodlands for biodiversity. It provides advice and practical guidance on managing deadwood to support sustainable forest management and the UK Forestry Standard Guidelines on Forests and Biodiversity. The guide includes detailed but easy to use procedures for assessing deadwood content at the level of the tree and the landscape. The tables of information are especially useful and provide guidance from assessment of deadwood content and its conservation value, through to the creation of improved deadwood components to a system. Designed for managers and owners as well as conservationists, the short book makes a good deal of information accessible in a single, convenient package. Furthermore, the approach addresses issues such as improvements to specific woodlands and strategic, longer-term developments and landscape or ecological corridors and continuity. For the tree manager, be they a forester or an arboriculturist, this book is extremely informative and very helpful. Indeed, the information is an ideal accompaniment to Ancient and Other Veteran Trees: Further Guidance on Management, edited by David Lonsdale, and fits well with our journal special theme of ancient and veteran trees. This publication is also available as a free download on the Forestry Commission website at: www.forestry.gov.uk/publications.