Advice to planning authorities considering proposals affecting ancient woodland

This page sets out our standing advice to all planning proposals that may affect (directly or indirectly) ancient woodland.

If we are consulted on proposals where ancient woodland is a constraint, we will not provide bespoke advice, except where the ancient woodland is part of a designated site.

This guidance is designed for use by planning authorities when making decisions on development proposals affecting ancient woodland.

It will also be useful for decision-makers who are responsible for major infrastructure projects, such as road and rail schemes.

NRW advice on developments affecting ancient woodland

Planning Policy Wales recognises the significant value of ancient woodlands and makes provision for their protection against damage or loss.

We advise that planning permission should be refused if development will result in the loss or deterioration of ancient woodland, given that ancient woodland is irreplaceable unless there are wholly exceptional reasons.

Where a decision maker is satisfied there is a wholly exceptional reason, every endeavour should be made to minimise and compensate for loss.  Although a compensation strategy cannot fully compensate for loss of ancient woodland it should include:

  • planting new native woodland or wood pasture to improve the resilience of ancient woodland;
  • restoration of or managing other ancient woodland, including plantations on ancient woodland sites, and wood pasture;
  • proposals connecting woodland and ancient and veteran trees separated by development with green infrastructure;
  • long-term management plans for new woodland and ancient woodland;
  • planting individual trees that could become veteran and ancient trees in future;
  • monitoring the ecology of the site over an agreed period.

How and when should potential effects on ancient woodlands be considered?

The Ancient Woodland Inventory identifies woodlands that have had continuous woodland cover for some centuries. Studies show that these woodlands are typically more ecologically diverse and of a higher nature conservation value than those developed recently or those where woodland cover on the site has been intermittent. These woodlands may also be culturally important.

Find all areas designated as ancient woodland in Wales on the Lle website

The map shows the boundaries of ancient woodland across Wales.

Read how ancient woodland is categorised or make an enquiry about a specific piece of woodland

The ancient woodland inventory can be used to help decide whether a stand-off zone is needed to protect the ancient woodland from the potential impacts of the development proposed. The stand-off or protection zone should eb based on evidenced survey and assessment.

Developers and Local Planning Authorities can assess the potential impacts on ancient woodland using the Forestry Commission's Assessment Guide.

Avoid impacts, reduce (mitigate) impacts, and compensate as a last resort

Applicants/developers should identify ways to avoid negative effects on ancient woodland or ancient and veteran trees. This could include selecting an alternative site for development or redesigning the scheme.

Read our advice to developers on avoiding or mitigating effects on ancient woodland

Local planning authorities should ask developers for a tree survey and an ecological survey, where appropriate.

The tree survey should follow guidance in British Standard BS 5837 ­ ‘Trees in relation to demolition, design and development’.

Ecological assessments

Preliminary Ecological Appraisals (PEA)

Preliminary Ecological Appraisal (PEA) is the term used to describe a rapid assessment of the ecological features present, or potentially present, within a site and its surrounding area (the zone(s) of influence in relation to a specific project).

A PEA normally comprises a desk study and a walkover survey, the methods for which are further defined in Section 2 of the guidelines.

The key objectives of a PEA are to:

  • identify the likely ecological constraints associated with a project;
  • identify any mitigation measures likely to be required, following the ‘Mitigation Hierarchy’;
  • identify any additional surveys that may be required to inform an Ecological Impact Assessment (EcIA); and
  • identify the opportunities offered by a project to deliver ecological enhancement.

The Guidelines for Preliminary Ecological Appraisal (GPEA) | CIEEM set out how to undertake Preliminary Ecological Appraisals (PEAs) and the appropriate use of assessments within the planning process.

If a PEA report identifies that significant effects are likely on an ancient woodland then a full EcIA may be required.

It is possible to finalise an ecological assessment including that for ancient woodland based on a PEA alone providing the mitigation hierarchy is applied and clearly explained (i.e. we could accept a method statement that demonstrates construction impacts will be avoided and that would avoid the cost the developer would need to pay for an EcIA).

Ecological Impact Assessments (EcIA)

Ecologists undertaking an Ecological Impact Assessment should follow the Guidelines for Ecological Impact Assessment (EcIA) | CIEEM.

The guidelines also provide decision-makers and those submitting projects with an indication of the information needed to adequately consider projects in the light of biodiversity legislation and policy.

Code of practice for planning and development - BS 42020:2013 Biodiversity. Code of practice for planning and development (

The above guidance documents include everything that an applicant and/or your consultant will need to address to assess:

  • zone of influence;
  • baseline survey and evidence;
  • determining sensitivity/ value of the receptor;
  • significance of impact;
  • mitigation/ compensation;
  • what are the pathways for effects;
  • how should effects be considered.

Existing condition of ancient woodland

Ancient woodland sites are valuable because of the long ecological history which results in diverse species and habitats and characteristic woodland soils.  A woodland in poor condition is likely to have remnant features and can be improved with good management. Development proposals should enhance the condition of existing ancient woodland, where possible. The existing poor condition of ancient woodland should not be seen as a reason to give permission for development which would cause loss, further detriment or provide a barrier to future improvement.

Use of stand-off or protection zones

A stand-off or protection zone’s purpose is to protect ancient woodland. The size and type of stand-off or protection zone should vary depending on the scale, type and impact of the development.

The BS 5837 Tree Survey, PEA and/or EcIA assessments should be used to inform the stand-off or protection zone for each individual woodland and veteran and ancient trees. Some zones may only require a root protection area to prevent negative impacts on individual trees or groups of trees, and others are likely to extend further. For example, the effect of air pollution from development that results in a significant increase in traffic or point source. Guidance is available on our Ammonia Assessment pages on the distance required for screening potential effects from ammonia.

Guidance is available on our Ammonia Assessment pages on the distance required for screening potential effects from ammonia.

Where possible, a stand-off or protection zone should:

  • contribute to wider ecological networks;
  • be part of the green infrastructure of the area.

It should consist of retained semi-natural habitats such as woodland and/or a mix of native scrub, grassland, heathland and wetland.

Developers should consider if public access is appropriate and only allow access on foot to stand-off or protection zones if the habitat is not harmed by trampling.

Developers should avoid including gardens in stand-off or protection zones.

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