Trees are a vital component of both urban and rural landscapes and their benefits are immensely valued by citizens of the United Kingdom. Tree risk management aims to look after these assets in such a way that their benefits are maintained and enhanced. In doing this, tree management aims to manage the level of risk so that people are not exposed to unacceptable risks of death or serious injury.
The National Tree Safety Group (NTSG), a grouping of national agencies involved in the management of trees, has produced Managing Risk from Trees to support the work of those involved in tree management of any kind – for example trees in streets trees, parks, public open spaces, businesses such as hotels or farms and private gardens of different sizes. The range of membership interests spans professional bodies such as the Arboricultural Association, Institute of Chartered Foresters, London Tree Officers Association, and Royal Institute of Chartered Surveyors, tree owners / managers including Forestry Commission, Country Land and Business Association, National Farmers Union, National Trust, and the Woodland Trust, and organisations with heritage / conservation interests such as Ancient Tree Forum and English Heritage. Its membership is open to all interested stakeholder organisations and groups.
The statement has relevance to all settings and environments in which trees occur. It will also be of interest to those involved in insurance and litigation in relation to tree management. It focuses on deaths and physical injuries resulting from accidents. However, the overall approach, namely that a balance should be struck between risks and benefits, is also relevant to agencies concerned with other issues such as visitor safety and cultural and environmental values. The statement includes the summary above and the following full statement. The summary aims to state the key points of the full statement in a more accessible form, for a non-technical audience.
Concern about how safety is being managed and doubts about the exact responsibilities of owners and managers, especially in the immediate aftermath of landmark legal cases concerned with tree-failure related injury or death, whether arising from criminal and civil courts, may lead to reactive (defensive) behaviour, unnecessary expenditure and loss of mature trees. This ignores dependable evidence that deaths and injuries caused by falling trees (or parts of trees) are rare. Despite the fact that millions of trees grace our landscape and that nearly everybody passes under a tree more than once a day, there are only about six deaths a year. In order to address this situation, and in response to industry and landowner consultation that has demonstrated a desire to acknowledge the concerns of both professionals and the public, the National Tee Safety Group has prepared this statement
Managing Risk from Trees:
National Tree Safety Group statement
In any human activity, there is an element of risk. Three factors are central to determining whether or not the level of risk is acceptable or tolerable:
• the likelihood of coming to harm
• the severity of that harm
• the benefits, rewards or outcomes of the activity.
Judgements about the acceptability of risk are made on the basis of a risk assessment. Risk assessment and management are not mechanistic processes. They crucially involve making judgements about acceptability based on an understanding of the balance between risks and benefits. Even where there is a risk of fatal or permanent disabling injury, this risk may sometimes be tolerable. For instance, going walking in an ancient forest involves an unavoidable risk of fatal injury, but this risk is tolerable for most people because in most circumstances the likelihood of coming to harm is very low and there are obvious benefits. Social and psychological factors are also important in risk assessment. Risks that are acceptable in one community may be unacceptable in another, and policies should take this into account.
Almost any environment contains hazards or sources of harm. In many cases, the existence of hazards can be justified, perhaps because they are impossible to remove or perhaps because their removal would have undesirable consequences or be too costly. Where the existence of a hazard can be justified, measures should be in place to manage it. In a controlled environment such as a workplace or a park, those responsible are required by law to identify and make informed judgements about, the hazards to which people are exposed. They must take steps to ensure that the risks are managed and controlled so far as is reasonably practicable while allowing the potential benefits to be delivered.
Trees and Risk
It is difficult to conceive of a countryside or town without trees, at least of one that people would want to live in and, in reality, such a world would not support human life. This is because trees are fundamental to our continued existence, to our well-being and the quality of our lives.
Trees are no less important in the rural landscape than in towns as the air-conditioning and climate control influence they provide is widely beneficial. Indeed many rural landscapes are defined by their trees and visited for their enjoyment. However, four out of five people now live in towns, where the pressures of modern living and therefore the benefits of trees are most strongly felt. Trees contribute directly to our quality of life. On a social level they have a profound effect, reducing crime, stress and mental ill-health, attention deficit disorder, even improving hospital recovery time.
It is the job of all those responsible for looking after trees to assess and manage the level of risk so that people can enjoy all their beauty without exposing them to unacceptable risks. This is part of a wider remit to care for our landscapes and to enhance people’s quality of life that is itself enshrined in both duty and policy. If we do not look after our trees we will greatly diminish our towns and cities, affect people’s health and impede the development of our children. Playing in trees has always been part of childhood and, although occasionally a child will hurt itself doing so, they gain direct experience of the consequences of their actions and choices and therefore a vital understanding of the extent of their abilities and competencies. Trees, therefore, are understood to have some risk attached to them but one that is widely accepted as ‘natural’ and indeed important.
Tree management and risk
Risk-taking is an essential feature of many of our interactions with trees, and of all environments where trees are part of leisure activities. In such circumstances, tree management aims to offer people the chance to encounter acceptable risks as part of a stimulating and beautiful environment. Tree management must also address other consequences of our desire to have trees in our lives. Some of these, such as subsidence and damage to property may be negative and others, such as the provision of shade or reduction of noise, may be positive. Tree risk management should aim to manage the balance between the sustainability and benefits of trees and the harm they may cause, including to human safety.
While the same principles of safety management can be applied both to workplaces generally and tree management, the balance between safety and benefits is likely to be different in the two environments. In tree risk management, exposure to some risk is actually a benefit: it satisfies a basic human need and gives people the chance to enjoy a valuable natural resource. Therefore it is acceptable that in the management of trees people may be exposed to the risk of minor and easily-healed injuries such as bruises, grazes or sprains. On the other hand, tree management should not expose people to significant likelihood of permanent disability or life-threatening injuries. However, it may on occasions be unavoidable that tree management exposes people to the risk to the very low risk of serious injury or even death. But this would only be tolerable under the following conditions:
• The likelihood was extremely low
• The hazards were clear to users
• There were obvious benefits
• Further reduction of the risks would remove the benefits
• There were no reasonably practicable ways to manage the risks
For example, a mature tree in a city park involves a low but irremovable risk of falling on somebody, even if it is frequently inspected and treated, but this risk is usually tolerable. The likelihood is typically low, the hazard is clear and people benefit through retention of a feature that is inextricably linked to why they visit the park. Further reduction of this risk is not possible without removing the tree and taking away the benefits.
Providers should strike a balance between the risks and the benefits. This should be done on the basis of a risk assessment. Crucially, this risk assessment should involve a risk- benefit trade-off between safety and other goals, which should be spelt out in the provider’s policy. One of the factors that should be considered is the time it takes a tree to develop to maturity and the extra benefits that such maturity brings. Sustainability and the maintenance of a mature canopy for current benefit must fit with plans for eventual replacement and the time needed for it to mature. Sensible management now measured against well-designed policies will help to ensure future safety too.
Clear, well-understood policies, together with procedures that put these policies into practice, are the key to good practice in risk management of trees. Policies should state clearly the overall objectives. Procedures, including risk assessment, should state how these policies are put into practice, giving guidance but also recognising the need for professional judgement in setting the balance between safety and other goals. Such judgements are clearly multidisciplinary in nature.
Safety in tree risk management is not absolute and cannot be addressed in isolation. Tree management needs to integrate the need to maintain a sustainable and valuable tree canopy with the safety of those who pass under it. Arboricultralists, managers and owners will need to reach compromises in meeting these sometimes conflicting goals. These compromises are a matter of judgement, not of mechanistic assessment. The judgements should be based on both social attitudes and on broadly-based expert opinion informed by current good practice. They should be firmly rooted in objectives concerned with people’s enjoyment and benefit. And they should take into account the concerns of stakeholders. Ultimately the basis of these judgements should be made clear in the policies of the tree owner as written down in policy documents. These policies should, in turn, be understood and embodied in practice by all the key stakeholders.