Tree management policy

This Section explains when the Council will take action.  Deciding what action to take is covered in Section 8.0.

6.1 Reasons for tree works

In general, tree works can be done either to address a problem, or to make an improvement.  Examples include pruning to remove a defect or an obstruction, and removing one tree to benefit the growth of another.

There are many reasons why tree works might be desirable, some of which may require specialist knowledge.  More than one reason may apply.

This policy sets out the reasons the Council will prune or remove trees.  These are where it is:

• Required by law
• Necessary for safety
• To maintain suitable clearances
• The most effective and proportionate way to prevent damage
• Part of routine pruning cycles
• To enhance the tree or wider treescape
• To meet other defined objectives

Works that do not meet one of these reasons will not be done.  For example, works to satisfy an individual preference will not be done unless they also fall within another justification.

The sections that follow provide further information on how each of the reasons will be defined and applied.

Our website also summarises these Tree Management Principles to help people to understand when we will do tree works.

6.2 Legal requirements

Sometimes tree pruning or removal is required by law.

Specific requirements or instructions are uncommon. For example, a Statutory Plant Health Notice may require the removal of trees to prevent the spread of a disease.

More commonly, tree management may be necessary to meet legal obligations where the outcome is defined, but the tree management is not specified.  For example, maintaining accessibility along a pavement.

This Policy does not seek to reiterate the law. The Council will work within the law and discharge all duties placed on it in relation to the management of its trees.

All of the topics that follow are also relevant to the legal framework around tree management and how the Council will discharge related duties.

If tree management is engaged by other legal requirements (those that are not principally about trees), the Council will take advice as required and meet its obligations, in accordance with this Policy.

6.3 Safety

The Council will undertake tree works where it is the best way to keep trees reasonably safe (This can be understood to include common law and statutory duties of care).  It will proactively identify hazards and reduce risks that are unacceptable.

Tree works for safety are a high priority for the Council.  This means that other activities may sometimes be done after more urgent safety works.  For example, following a major storm.

Works will not be undertaken in response to a perception of risk, or a concern. 

Risk will be assessed in a structured and systematic way during tree inspections by competent arboriculturists, and action will be taken based on the risk assessment.  This ensures consistency, and helps to avoid unnecessary work, expense and damage to trees.

The Council will not try to remove all risk because this would do significant harm.  Some risks are tolerable on consideration of the benefits that would be lost in order to reduce risk further. This means that some level of remaining risk will not necessarily justify tree works.

Where the Council’s risk assessment identifies a risk that is not tolerable, tree works will be considered as a possible solution. 

Sometimes other solutions may be preferable for reasons such as sustainability, speed or safety.

6.4 Risk assessment

The Council will make a risk assessment against every record in its tree inventory.  In this way, every tree will have a current risk assessment, whether this is individually, or as part of a group or woodland.  These will be done during tree inspections by competent and experienced arboriculturists.

The time period during which each assessment is expected to remain reliable will be defined, up to a maximum of five years. The assessment and all supporting information will be updated before this date, either during the next planned inspection or in response to new information.

Risk assessments will consider:

• The condition of the tree and how is expected to develop and behave
• What harm the tree could cause
• How the context of the tree influences the likelihood of harm occurring

The assessment process will consider one or more specific scenarios.  For example, the condition of a branch with a defect, the harm that branch could cause if it fell, and what is beneath it.

The outcome of each risk assessment will be tested against a defined threshold, representing tolerable risk.  Where this test is failed, an intervention will be made to reduce the risk to a tolerable level.

The Arboriculture team will maintain an operating procedure that sets out the Council’s current approach in detail. This will cover the risk assessment methodology, thresholds or definitions for tolerable risk, the use of zoning, and what tools and software will be used. The operating procedure will support this policy.

6.5 Clearances

This section is about situations where the presence of trees may prevent the proper function or operation of something else, normally by causing an obstruction.  The potential for damage caused by contact with a tree is covered in the next section.

There is no general requirement for clearances between trees and other objects.  The Council will not generally prune trees because of proximity to a structure.

If a tree is blocking a streetlight or a road sign, we will address this, such as by pruning the tree.

Where a tree overhangs a public highway, footpath or track and endangers or obstructs the passage of vehicles or other users, the Council will remove the cause of the danger or obstruction.  This only applies to Council trees.  In the case of trees on private land, the Council may serve notice on a landowner to do the same.

The inspection and maintenance of the highway, including streetlights and road signs, is the responsibility of the Highway department, which will consult the Arboriculture team to arrange remedial works where necessary.

Where trees interfere with important public services, we will consider tree pruning or removal.  For example, where trees grow to block critical sight lines or signals.  This does not normally include private interests or land, or trees that were already present when the interference began.

Where it is possible to do so, the Council will monitor and anticipate tree growth that may cause these types of obstruction or interference during its tree inspections.

Contact between tree roots and underground equipment is common and not normally a problem.  Roots do not normally affect modern pipes and cables unless they are already damaged or leaking. It is not possible to monitor root growth during routine tree inspections and the Council will not prune or remove trees, or their roots to prevent underground contact.

Some clearances are the responsibility of others, including on Council land. 

These are generally those delivered by statutory undertakers, such as the operators of overhead power lines.

Maintaining clearances on private land is normally a matter for the landowner.  Branches from Council trees that are interfering with the use of private land may be pruned. There are laws governing what is allowed and this is not an unqualified right.  If you think this applies, you should contact the Council before doing anything.

6.6 Property damage

The owner of a tree, including the Council, may be liable for damage it causes to property.  The Council will manage this risk where possible by taking steps to identify foreseeable damage, mitigating risk, and responding where damage occurs.

The Council inspects all of its trees and assesses risks associated with ongoing or foreseeable damage. These assessments are made by qualified arboriculturists, according to our tree risk assessment methodology. Other Council activities such as highway inspections, and reports by third parties may also inform them.

Some types of damage are more predictable, such as those associated with continued growth of branches or stems; we will assess these and try to prevent them.  Others are inherently less predictable, such as those associated with roots; we will generally respond to these as they arise.

Wherever damage is, or will be caused by a Council tree, we may undertake remedial and/or preventative work to the tree, the environment, or to the structure.  We will prune or remove trees where this is the most effective and proportionate solution.

Preventative measures may include pruning as well as other measures, such as to the affected structure, where this is straightforward.  For example, we will not prune trees to prevent damage to an overhead telephone line unless it is not reasonably practicable to resolve the issue by adjusting the line.

The Council will not improve structures by any repair or replacement it makes except as a discretionary measure to prevent recurrence.

The Council will decide how to manage the risk of future damage associated with its trees, whether damage has occurred or not. It will not automatically remove or prune trees where damage has occurred. When deciding what to do, we will balance the risk and cost of damage against the benefits provided by trees.  For example, where repairing or modifying a structure would allow the retention of a significant tree.

In order to establish responsibility for any damage that has occurred, the Council will require evidence demonstrating the damage, the role of the tree, and that other contributing factors have been considered.  In the case of underground damage, this normally requires intrusive exploratory works.  In all cases, the evidence required will be relevant and in proportion to the claim.  The Council may also seek clarification, advice, and make its own assessment.

The Council will not accept a presumption of damage by a tree or unsubstantiated claims as a basis for action.

Landowners can prune Council trees that grow across a property boundary and cause damage. There are laws that cover what is and is not allowed.

You should contact the Council before you do this.

6.7 Routine pruning

The Council will undertake tree pruning that is required for the benefit of the tree, or to preserve a pre-existing growth pattern or form.

This does not include pruning to keep a tree at a certain size, or away from a structure.  These are covered by other topics.

Routine pruning includes:

• Re-pollarding, where a tree is already pollarded and failure to continue would be detrimental
• Coppicing, where a tree is already in a coppice management cycle
• Crown cleaning, to remove potential future defects or failure points
• Formative pruning, to encourage future healthy growth
• Hedge maintenance, including cutting, flailing, and laying

6.8 Enhancement

Tree management activities provide opportunities for enhancement of the tree population as well as maintenance.  These may include interventions that improve the condition of individual trees, as well as those that change the characteristics or composition of the treescape overall.

Generally, works for this reason are done where there is an opportunity to increase the benefits and services that trees are providing.  However, they may also include interventions to protect benefits by addressing vulnerabilities. For example, by increasing the diversity of tree species, age and type. 

Tree works for enhancement are normally undertaken on the initiative of the Council rather than in response to a request or a duty. They may be specific operations, or outcomes reflected in the way that other objectives are delivered.

The main types of enhancements that may justify tree works, which the Council will routinely consider include:

• Biodiversity and habitats
• Visual amenity
• Screening (e.g. light, buildings, sound and dust)
• Environmental benefits (e.g. air quality and water management)
• Placemaking, landscape design and character
• Heritage and cultural benefits
• Climate resilience and adaptation
• Social, community and economic benefits
• Health and wellbeing

This is not an exhaustive list.  Any tree works that would increase the quality, condition or value of the tree population will be considered.

Works that represent value for money may be done where this would not jeopardise other priorities, such as safety.

6.9 Other objectives

Sometimes tree works are justifiable for reasons that do not start with the tree or its surroundings.

The Council has a broad remit and is involved in lots of different activities.

From time to time, tree pruning, or even tree removal may be justified in order to achieve other benefits or objectives. These might include development, improvements to public spaces, events, or the delivery of other Strategies or Policies.

Where works would enable clearly defined benefits, these will be weighed against any harm that would be caused, such as tree removal.  Where harms can be mitigated, such as by tree planting, that will also be considered.  There will be a presumption against harm to trees, but where the benefits clearly outweigh the harm, tree works may be justified.

The efficiency and resilience of the Council’s tree management services is important, because it underpins the delivery of everything in this policy.  Tree works may be done where they reduce tree management costs over the longer term and/or improve standards. Interventions may also be made to maintain the capacity and function of the service. For example, by preventing ‘spikes’ in demand associated with seasonal pests or disease.

Where works would cause negligible or no harm, they may be permitted even where they would provide only a small benefit. One way that this principle may be applied is to allow works to a Council tree that are funded by a third party.  When making this decision, we will consider a range of possible harms including to tree health, amenity, wildlife and environmental benefits.  In such cases, the Council will normally undertake the works in order to control quality.   This is a discretionary function, and the Council will make the final decision.

6.10 Exceptions

Works that are proposed or requested which do not fall under any of the above reasons will not be done, unless exceptional circumstances justify it.

By definition, these situations are exceptional and therefore uncommon and unusual.  They also tend to relate to what is around a tree, rather than to the tree itself.

We consider the context of each tree when we make routine tree management decisions. However, there may be information that is not available during tree inspections that changes whether action should be taken.

Examples might include the prevention of a type of effect to which a person or object is unusually vulnerable or sensitive.

Cases will be considered individually on their merits, balancing harms against benefits according to this policy, and the Council will decide whether to act.  Exceptional circumstances that justify works are rarely replicated.

Therefore, such outcomes will not set a precedent that directs future decision making.