The section 6 biodiversity duty in Welsh planning decisions
The section 6 duty falls on the authority, not the applicant. Writing the ecology chapter around the resilience attributes makes the officer's job, and your case, easier.
This article deals with Wales. The section 6 duty in the Environment (Wales) Act 2016 requires a public authority to seek to maintain and enhance biodiversity in the exercise of its functions in relation to Wales, and in doing so to promote the resilience of ecosystems, so far as consistent with the proper exercise of those functions. In planning terms that duty falls on the local planning authority and on Welsh Ministers, not on the applicant.
The practical consequence for anyone preparing an application in Wales is that the officer has to record how the duty has been discharged. An ecology chapter written to make that easy carries weight that a longer, generic one does not.
What the section 6 duty requires of authorities
The wording is stronger than the English equivalent and the difference is deliberate. Section 40 of the Natural Environment and Rural Communities Act 2006 requires an authority in England to have regard to conserving biodiversity. Section 6 in Wales requires the authority to actively seek that outcome.
"Seek to" imports an obligation to try, which is a positive duty rather than a consideration to be weighed and discounted. The qualification at the end, so far as consistent with the proper exercise of the function, is what allows an authority to grant permission that causes some loss, provided the duty has been engaged and the reasoning is on the record.
Authorities also have to publish a plan setting out what they propose to do to comply, and report on it periodically. Those plans are public, and a plan that commits the authority to particular outcomes is a useful document to cite in a supporting statement.
Section 7 of the same Act carries the list of living organisms and habitats of principal importance for biodiversity in Wales. It does the same work as the section 41 list in England and the two lists are not identical, so check the Welsh list rather than assuming.
How it differs from a net gain calculation
England's mandatory biodiversity net gain under the Environment Act 2021 is a numerical regime. A statutory metric, a 10 per cent minimum, a biodiversity gain plan approved by the authority, and a 30 year management obligation. A Biodiversity Net Gain Assessment prepared for an English site follows that structure, and the Environment Act regime expects the metric to be completed by a competent person.
Wales has no equivalent statutory metric in planning. The test is net benefit for biodiversity, applied through the step-wise approach in Planning Policy Wales, and it is qualitative.
That has two consequences. A metric output from an English project has no standing in a Welsh decision, and submitting one without a written case is worse than submitting nothing, because it signals the wrong framework. And because there is no number to hide behind, the reasoning has to be explicit: what is being lost, what is being created, why the creation amounts to a benefit, and how long it will be maintained.
Some Welsh authorities ask applicants to run a metric voluntarily as supporting evidence. That is a local practice rather than a statutory requirement, and it should be presented as supporting the qualitative case rather than replacing it.
Resilience attributes explained
The Act frames resilience through five attributes, and an assessment that works through them in order reads as a section 6 assessment rather than a generic ecology chapter.
Diversity, meaning the variety between and within habitats on and around the site. Connectivity, meaning the links between them, including hedgerows, watercourses and verges that carry species between larger areas. Scale, meaning the extent of the habitat. Condition, meaning its structure and how it functions. And adaptability, meaning its capacity to absorb change, including climate change.
Adaptability is the one usually skipped and the one that distinguishes a serious assessment. Planting a native hedgerow of a single species scores on diversity and connectivity and very little on adaptability. A mixed hedgerow with standard trees, managed on a rotation, does better on all five.
Apply the attributes to the proposal rather than to the site in the abstract. The question the officer has to answer is whether this development, as proposed, promotes resilience, and an assessment that describes the baseline beautifully and never returns to the scheme leaves them to do that work themselves.
Evidence that satisfies the duty
The evidence base scales with the proposal, and the minimum for anything beyond householder work is a habitat baseline from someone competent to produce one.
A preliminary ecological appraisal gives the habitat classification, the protected species risk and the further survey programme. Where protected species are likely, a protected species survey by a suitably licensed ecologist is legally required under the Conservation of Habitats and Species Regulations 2017 and the Wildlife and Countryside Act 1981, and an AI-assisted draft is a starting point for that ecologist rather than a substitute for their survey or their licence.
Beyond the survey, four pieces of evidence do most of the work in a Welsh submission. The local development plan's ecological network mapping and any green infrastructure policy. The relevant Natural Resources Wales area statement, which sets out regional priorities and is directly citable. The local environmental records centre data. And the authority's own published section 6 plan.
Citing the authority's own plan back to it is the single most effective move available, because it lets the officer connect the proposal to a commitment the council has already made.
How officers record compliance in reports
Look at recent committee reports and delegated reports from the authority you are dealing with. Most Welsh authorities now include a standing section headed with the section 6 duty, and the quality of what goes in it varies enormously.
The good ones set out the baseline, the step-wise assessment, the residual effects, the net benefit and the conditions securing it, then conclude that the duty has been discharged. The weak ones say the proposal includes landscaping and conclude the same thing.
Write your ecology chapter so that a busy officer can lift the structure into their report. Use the same headings. State the conclusion in a sentence that could be copied. That is not a trick, it is how a supporting statement earns its place, and the equivalent discipline applies to any planning report type you prepare.
Appeals where the duty was not addressed
Planning and Environment Decisions Wales determines appeals in Wales, and inspectors there apply the duty as part of the decision rather than as a policy consideration to be balanced away.
Two failure patterns recur. An authority refuses on ecological grounds without identifying the loss or engaging with the proposed mitigation, which makes the refusal reason hard to defend. Or an authority grants without recording the duty at all, which exposes the permission to challenge by a third party.
From an applicant's side, the appeal point to make is not that the duty is satisfied because the scheme includes planting. It is that the step-wise approach was applied in order, that avoidance was exhausted before mitigation, and that the residual position delivers a net benefit with the attributes named. Decisions of this kind are indicative of how inspectors approach the issue rather than binding precedent.
Practical drafting for an ecology chapter
Keep the structure short and in this order.
- Baseline, with survey dates, method and limitations stated plainly.
- Step one, avoidance: what the design changed to protect, with drawings referenced.
- Step two, mitigation: what is unavoidable and how it is reduced.
- Step three, compensation: what remains and what replaces it.
- Net benefit: what is created, at what scale, and against which resilience attributes.
- Delivery: conditions or obligations, management period, responsible body, monitoring.
- Conclusion on the section 6 duty, in one paragraph.
Say what the scheme cannot do as well as what it can. An assessment that reports a residual loss of one section 7 habitat, explains why it is unavoidable and sets out the compensation, is more persuasive than one that reports no harm anywhere.
This is general guidance, not legal advice, so check the position with the local planning authority or a qualified ecologist before relying on it. PlanScope's drafting is grounded in English policy, so a Welsh submission needs the reviewer to check it against Planning Policy Wales, the Technical Advice Notes and the adopted local development plan.
PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.
Frequently asked questions
Who does the section 6 duty apply to?
Public authorities exercising functions in relation to Wales, which in planning means the local planning authority and Welsh Ministers. It does not apply to the applicant. The practical effect is that the officer has to record how the duty has been discharged, so a supporting statement structured around it makes that record easier to write.
How does section 6 differ from the English duty?
Section 40 of the Natural Environment and Rural Communities Act 2006 requires authorities in England to have regard to conserving biodiversity. Section 6 in Wales requires them to actively seek that outcome, which is a positive obligation to try rather than a consideration to be weighed and set aside.
Does biodiversity net gain apply in Wales?
No. Mandatory biodiversity net gain with a statutory metric and a 10 per cent minimum is an English regime under the Environment Act 2021. Wales applies a qualitative test of net benefit for biodiversity through the step-wise approach in Planning Policy Wales. Some Welsh authorities ask for a metric voluntarily as supporting evidence.
What are the resilience attributes?
Diversity between and within habitats, the connections between them, their scale, their condition including structure and functioning, and their adaptability to change. An assessment that works through all five, and applies them to the proposal rather than to the baseline alone, reads as a section 6 assessment rather than a generic ecology chapter.
What is the section 7 list?
It is the list under the Environment (Wales) Act 2016 of living organisms and habitats of principal importance for biodiversity in Wales. It performs the same role as the section 41 list in England, but the two lists are not identical, so check the Welsh list rather than carrying an English one across.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.