Management of Council Owned Trees Policy

The policy ensures that the council meets its legal and Health and Safety obligations, provides clear guidance for officers to implement.

The policy also recognises the value of trees to the natural environment in terms of landscape, ecology and climate change.

Dorset Council currently owns in the order of 250,000 trees situated across the highway network, amenity and open space areas, the DC property estate and other areas of council owned land.

Trees make a significant contribution to the quality of our environment in a number of ways including:

• improving air quality, micro-climate characteristics and mitigating the ‘urban heat island’ effect in towns
• providing aesthetic, mental health and social benefits
• providing a sense of place, continuity and belonging
• contributing to the urban design, landscape and character of the county, including flood mitigation
• contributing to the ecological network through providing habitats for a range of wildlife, especially in urban areas
• as ancient, veteran or notable trees in their own right – providing high biodiversity, cultural and heritage value
• contributing to carbon storage and offsetting to help mitigate climate change

Trees adjacent to the highway are subject to particular conditions as set out in the Highways Act 1980 and other relevant highway best practice. (Appendix 1).

Dorset Council will manage its trees to ensure that it meets its legal responsibilities regarding public safety, for example

• Health and Safety at Work Act 1974
• Duty of Care, Managing Health and Safety at work Regulations 1999 
• Highways Act 1980
• New Roads and Street Works Act 1991
• Working at Height Regulations 2005
• Occupiers’ Liability Act 1984
• Well Managed Highway Infrastructure guidelines

Public safety is of paramount importance when making decisions about trees and the council has in place programmes for the regular inspection and maintenance of its trees (see Appendix A for inspection frequencies).

These inspection frequencies are based upon Industry guidelines but can be varied according to identified local needs and budget. The council will take into account the guidance given by the National Tree Safety Group’s ‘Common Sense Risk Management of Trees’ and the HSE, in its work to achieve this.

Community safety - Consideration will be given on a case by case basis for additional pruning over and above the tree maintenance schedule where serious obstruction of CCTV coverage by trees has occurred. Primarily this will address community and public safety priorities where critical factors apply.

The welfare of trees and the maintenance of our tree stock will be of paramount importance when considering the extent of any additional tree works for CCTV coverage.

The council will ensure that all council tree work is carried out in accordance with BS3998:2010 British Standards Recommendations for Tree Work, and BS5837:2012 Trees in Relation to Design, Demolition and Construction.

All tree work will be conducted in line with policy and legislation requirements relating to wildlife.

This includes the:

• Wildlife and Countryside Act 1981 (as amended Countryside and Rights of Way Act 2000)
• Conservation of Habitats and Species Regulations (amended EU exit 2019) and Statutory Notices under the Plant Health (Forestry) Order 2005 

Dorset Council’s Tree Policy will contribute to the Council’s duty to conserve and enhance biodiversity, as required under the Natural Environment and Rural Communities Act 2006 and advocated in the Dorset Council Biodiversity Strategy amended 2010).

Planning applications for development on council land where trees are affected should be accompanied by a BS5837:2012 (Trees in relation to design, demolition and construction) survey and an Arboricultural Impact Assessment.

They will also be assessed under the Dorset Biodiversity Appraisal Protocol to ensure that all impacts on biodiversity (including those on protected species associated with trees such as bats which are a European Protected Species) and impacts on Ancient/Veteran/Notable trees are avoided, mitigated or compensated and that the mandatory requirement for 10% net gain is achieved.

Relevant local, regional and national planning policy and guidance which relates to trees include the following, and proposed development will be assessed against the following policies:

• Planning Policy Framework 2019 (Chapter 15 – Conserving and enhancing the natural environment, particularly Para 175c on ancient and veteran trees and ancient woodland and Para 175a which sets out the biodiversity hierarchy)
• Section 197 of the Town and Country Planning Act 1990 (as amended 2012) which places a duty on local authorities to include appropriate provision for the preserving and planting of trees

The council’s planning tree officers will be responsible for the implementation and management of Tree Preservation Orders and for the implementation and management of Conservation Areas related to trees. Where appropriate, the council’s arboricultural team will liaise and work with the planning tree officers when carrying out work to trees in conservation areas or on trees with Tree Preservation Orders on them.

  All formal inspections will be carried out by suitably qualified and experienced inspectors.

Inspections will be carried out against categories of risk and at agreed intervals (appendix 2).

All inspection records will be captured and stored using a bespoke electronic data system called Ezytreev – a nationally recognised tree management package that ensures transparency and clear data capture and creates an audit trail from interval of inspection through to completion of identified safety works.

Informal tree inspections will be carried out and recorded by Community Highways Officers (CHO’s) as part of their highway network inspection schedule. CHO’s will also record any wider environmental conditions that they may consider as having negative impacts on surrounding Trees. Informal inspections will be recorded by the CHO’s on the Confirm system and any areas of concern will be reported to the Arb team via Confirm.

CHO’s will receive regular basic tree inspection training, (every 5 years) from the Arboricultural Officers. Online toolbox training will be provided to the Highway Operations staff.

Out of Hours call outs relating to tree issues will be reported by the duty supervisor to the Arb team who will carry out follow up inspections to ensure no further work is required. Works required to Council owned trees will be carried out by the Arb team, issues with privately owned trees will be dealt with by the CHO team.

Information regarding road closures or road space booking for tree works will be passed by the Highways team to the Arb team for consideration if additional inspection is required.

Dorset Council operates a presumption in favour of retaining trees unless there is a sound arboricultural reason not to do so. Measures such as coppicing, pollarding and canopy reduction will be used to ensure that every effort is made to conserve and enhance biodiversity while safeguarding the public.

This will particularly apply where a tree is Ancient, Veteran or Notable.

Trees will only be removed for sound arboricultural reasons such as:

• dead, dying or dangerous
• proven to be causing significant structural damage in subsidence claims
• considered by the arboricultural team to be an inappropriate species for the location i.e. Poplars or Robinia’s in pavements
• when removal is required as part of an agreed management plan, or as an overall agreed improvement project. For example, where a scheme has a robust project plan and there has been both public and Member engagement, or have been subject to the appropriate Planning process and assessment under the Dorset Council Biodiversity Strategy

Where a tree(s) is identified for removal an advanced notice(s) will be placed on the tree(s) to inform the public, except where urgent and emergency works apply. The local councillor(s) will also be informed.

The current policy of replacing one felled tree with one new one is to be altered so that for every tree felled, at least two new ones will be planted.

The council will replace trees wherever possible with regard to the ‘right tree for the right site’ and with the aim of achieving age and species diversification of its tree stock. Species selection will include, but not be exclusively, native species of value to the environment.

The opportunities for planting of trees in pavements and highway verges is limited due to the location of services, width of verge and the need to maintain sight-lines. 

The council has produced a ‘guide to tree planting’ leaflet which it will circulate to interested parties and members of the public who wish to plant trees on their own land. The council will also work with other interested parties to support the planting of trees throughout the county.

This Policy does not cover the planting of additional trees for landscape, ecological or climate purposes as these are covered by the Climate and Ecological Emergency Strategy and Action Plan, but once planted, they will be managed in line with the principles included in this policy.

The following reasons will not constitute grounds for the pruning or removal of trees by the council.

However, if it is possible to improve the situation through general maintenance, this work will be carried out at the appropriate time as part of the cyclical maintenance regime:

• obstruction of light and / or view
• aphid honeydew, leaf fall, the dropping of fruits, flowers and seeds
• renewable energy systems such as solar panels or wind turbines
• to improve satellite / digital television reception
• to clear telephone lines
• roosting birds in a tree and their droppings
• where a tree is perceived to be too large
• allergies associated with trees, for example pollen and seed dispersal
• someone willing to pay for the removal and replacement of a tree(s)
• causing disturbance to pavements or kerbs (in such cases an engineering solution will be sought if possible)

As a general principle, the council will not create new pollards on street trees which have not been previously pollarded. However, this may be considered as a measure to prolong the life of the tree where the tree has high existing biodiversity or potential biodiversity. 

An acceptable reason for pollarding a tree might be where a tree has been linked to subsidence and pollarding it is preferable to it being removed. Trees which have previously been pollarded will be repollarded every five years as appropriate.

Deadwood (standing or stacked alongside) will be retained on site wherever it is safe to do so for the benefit of wildlife.

The council will seek compensation from any external organisation, or individual responsible, for significant damage to, or removal of any council owned tree(s) to the value as calculated by the nationally recognised Capital Asset Value for Amenity trees (CAVAT) used by the council.

On the assumption that all council owned trees are managed in line with national best practice, any claim made of the council in relation to damage caused by a council owned tree will be thoroughly investigated and vigorously defended. 

In the case of subsidence claims, before any such claims can be considered by the council, the claimant will need to provide a range of information as shown in Appendix 3. 

Pollarding

removal of a tree’s branches to reduce its height and vigour, leaving only the trunk and stubs of large limbs.

Ancient tree

one which has passed maturity, has a compact crown and a wide trunk, which may be hollow.

Veteran tree

ancient trees are veteran trees, but not all veteran trees are old enough to be ancient. Veteran trees are such because their age, size or condition is of exceptional cultural, landscape or nature conservation value.

Notable tree

these have community or national recognition as being of special importance because they commemorate important events in a nation’s heritage e.g. the Tolpuddle Martyrs Tree or the Remedy Oak.

Street trees are a relatively recent introduction in England. Prior to the 19th century there were relatively few trees that were either planted or allowed to grow within the curtilage of the highway.

For the purposes of The Highways Act 1980, the ‘highway’ was defined not just as the carriageway (the road surface), but the adjacent footway running from the kerb edge all the way to the back edge of the pavement area. It also includes footpaths and public rights of way maintained at public expense.

Trees growing in the highway are usually the responsibility of the local highway authority and are managed and maintained just like any other element of the highway infrastructure that requires maintenance or replacement from time to time: lamp columns, bollards, kerb edging, signage, etc.

The current statutory requirement is for tree branches to be a minimum of 5.2m above the carriageway and 2.3m above footpaths, although where they combine with cycleways 2.5m is more appropriate. However, unlike other highway infrastructure trees do not remain static, they grow, enlarge over time, both above and below ground.

They shed leaves and branches, and in some situations may fall over presenting a hazard to users of the highway.

This growth and life cycle which may be perfectly benign in a natural setting is problematic when the tree interacts with the built infrastructure around it in a highway setting.

Trees can cause maintenance issues for kerbs, footway paving, carriageway surfaces, adjacent shallowly founded structures (direct damage) and in certain conditions damage building foundations as well, when growing in a shrinkable clay soil (indirect damage).

Despite all these issues, highway trees are a critical element in the overall canopy cover of the urban forest within towns in Britain.

As such, they make a significant contribution in respect of visual amenity and the many aspects of ecosystem services they provide to people living in towns.

Larger landscape scale trees provide the greatest overall benefits.

When managing highway trees, this will be done in accordance with the guidelines in the Well-managed Highway Infrastructure guidelines (WMHI). 

Unfortunately, it is often the larger trees, which, if not adequately maintained in the highway context, may cause the most issues for the built infrastructure in their immediate vicinity.

However, there are a range of engineering and maintenance solutions that can easily be applied throughout the trees’ life cycle that allow both the tree and the highway to mutually co-exist, each providing the benefits to society that are implicitly valued by residents and businesses in towns; safe, usable highways and a high quality, well managed and maintained urban forest.

Some examples, not exhaustive, are:

1. Use of flexible tree pit sizes, rather than relying on a small range of prespecified dimensions.
2. Use of narrow kerb profiles to accommodate trunk flare and buttress roots.
3. Dispensing with kerb edging when possible in appropriate streets.
4. Use of bonded gravel in the tree pit to provide an inclusively accessible surface.
5. Use of tarmac inserts around the base of trees where the footway surface has become deformed due to root growth.
6. Use of flexible rubber crumb along pavements and as inserts where previously tarmac or paving has been deformed due to root growth.
7. Integrating tree pit locations into parking bays as kerbside buildouts. 
8. Creating kerbside buildouts to accommodate tree growth or redirect pedestrian footfall.

Tree maintenance solutions:

1. Root pruning of non-structural surface roots to accommodate the laying of new paving, tarmac inserts, rubber crumbing surfacing.
2. Root pruning of non-structural roots to accommodate relaying of kerb edging.
3. Placing barriers around trees to discourage parking on verges.
4. Regular pruning of the tree to control its water uptake and limit its root and trunk annual incremental expansion.
5. All of the above solutions will require the co-ordinated response and guidance of an experienced and qualified Arboriculturalist working closely with an experienced Highway Engineer.

Some, such as the rubber crumb surfacing bring multi-purpose benefits in that larger areas of rubber crumb surfacing can act as a Sustainable Urban Drainage (SUD) element within the footway, by desynchronising flash flooding and providing additional available water to the tree itself.

Where there is potential for direct infrastructure damage as well as indirect foundation damage, the need for regular pruning of highway trees in particular can be difficult to justify to residents and incurs a cost.

However, tree management and maintenance is a long term management activity and many tree managers take the view that when necessary, it is better to retain a large species, large landscape tree and its root system in situ, but maintained at a reduced size.

This is done in the expectation that at some future date due either to; a technical innovation that solves that the issue of building subsidence, a change in climatic factors (increased winter rainfall rehydrating the soil sufficiently annually) or a cultural shift that means property owners tolerate minor cracking (as was the case prior to 1971 before mortgage lenders and insurers covered subsidence as an insured risk) the trees could be allowed again, to redevelop their larger canopies quickly if the worst case scenarios for climate change were realised in the 2050’s to 2080’s.

Thereby providing a quick response to the need for increased canopy cover, restoring them at just the moment in time when they will be needed most and without the time lag and challenge of replanting from scratch.

There is a wealth of technical advice and information available across the relevant sectors that provide practical and comparatively low-cost methods of achieving the objective of permitting highly valued trees to exist within a well maintained and modern inclusive highway.

These solutions will require effective communication to Elected Members and Managers, as well as to the public, as to why they are suitable and necessary for achieving good highway tree management practice.

For trees with known defects, irrespective of location, they will be inspected every 12 - 18 months, depending upon the nature and severity of the defect.

Using the DC carriageway hierarchy classification system (zoning), the following inspection frequencies will apply:

Carriageway inspections include the trees on them and are carried out by Highways Inspectors who have received basic tree inspection training. Any defects noted are reported to the Arboricultural Team for further inspection.

Subsidence claims made against the Council will need to provide the following information:

• plan, showing location of property and trees
• age of property
• depth and type of foundations
• details of relevant property extensions
• drainage details and location of other services
• extent of damage
• tree root data
• soil and subsoil analysis
• seasonal movement monitoring
• evidence of live roots of the same family or species found below the level of the foundation depth
• soil moisture tests at varying depths to below foundation level
• evidence of desiccated soil.
• a geotechnical survey including trial pits and soil profiles
• a structural report providing evidence of actual damage including crack monitoring records
• details of other vegetation within the theoretical zone of influence that is not easily visible from a public place
• level distortion survey

Biodiversity Strategy

Well Managed Highway Infrastructure

National Tree Safety Group 

Climate and Ecological Emergency Strategy 

Dorset Council Tree Planting Guide - How you can help fight climate change right now - Dorset Council

Health and Safety Executive (2001). Reducing risks, protecting people – HSE’s decision -making process. HSE Books. Sudbury.

Health and Safety Executive (2007). Management of the risk from falling trees. HSE Sector Information Minute, SIM 01/2007/05.

Mynors, C, (2011). The Law of Trees, Forests and Hedgerows. Sweet & Maxwell.

Fay, N, Dowson, D & Helliwell, R (2005). Tree Surveys: A Guide to Good Practice. The Arboricultural Association.

Lonsdale, D (2000). Managing hazards from trees: A general guide. Forestry commission, London.

Davis, C, Fay, N & Mynors, C (2000). Veteran Trees: A guide to risk and responsibility. English Nature.

Department of Transport (2005). Well maintained highways: code of practice for highway maintenance management.

This policy was last reviewed in 2021. 

The next expected review date is 2024.