Wales: the section 6 biodiversity duty on applications

The section 6 biodiversity duty in Wales falls on the local planning authority, not on you, but it is your evidence that lets the authority discharge it. Section 6 of the Environment (Wales) Act 2016 requires public authorities to seek to maintain and enhance biodiversity in exercising their functions in relation to Wales, and in doing so to promote the resilience of ecosystems. For a major residential or commercial application in Wales, that means the determining officer has to be able to write down how the scheme improves biodiversity. If your ecology chapter does not give them the material, the application stalls at the consultation stage rather than at committee.

Everything below applies to Wales. The statutory 10 per cent biodiversity gain condition created by the Environment Act 2021 is an England-only regime, and none of what follows describes English practice.

What the duty requires, and of whom

Section 6 binds public authorities. That includes the 25 Welsh planning authorities, Natural Resources Wales, Welsh Ministers and the National Park authorities. It is a duty to "seek to" maintain and improve biodiversity, qualified by what is consistent with the proper exercise of the authority's functions, so it is not an absolute bar on harm.

Two features give it teeth in practice. The duty applies to every decision, including minor applications and the discharge of conditions, and reaches well below the major threshold. And section 6(6) requires each authority to publish a plan setting out what it proposes to do and to report on it, which means officers are measured on the biodiversity outcomes they record.

Section 7 of the same Act sits alongside it. It requires Welsh Ministers to publish a list of living organisms and habitats of principal importance for maintaining and improving biodiversity in Wales, and to take steps to conserve them. That list is what a Welsh ecologist works from when deciding which habitats on your site carry weight, and it is not identical to the English equivalent under the Natural Environment and Rural Communities Act 2006.

The step-wise approach in Planning Policy Wales

Planning Policy Wales sets out a step-wise approach that decision-makers must apply, and it is the sequence your ecology evidence should be organised around. Check the current edition on gov.wales before you cite it, because the chapter numbering has changed between editions.

1. Avoid damage to biodiversity by locating and designing development to keep habitats and features intact.
2. Where harm is unavoidable, minimise it through design, phasing and construction method.
3. Mitigate residual harm on site.
4. Compensate for what cannot be mitigated, as a last resort.
5. Where harm remains after all four steps, the authority should refuse.

Welsh policy then goes a step further than the sequence. Development is expected to provide a net benefit for biodiversity, and the authority has to be satisfied that the scheme does so before permission is granted. There is no statutory metric behind that requirement and no fixed percentage, which cuts both ways: you have more freedom in how you demonstrate benefit, and less certainty about what will be accepted.

Technical Advice Note 5 on nature conservation and planning carries the procedural detail, including what the authority should expect by way of survey information and when it should consult Natural Resources Wales.

Evidence a Welsh application needs

The pack for a Welsh major usually runs to four ecology documents, and the gaps that cause delay are predictable.

A Preliminary Ecological Appraisal establishing habitats, their condition and the likely presence of protected species, with a desk study drawing on the local environmental records centre. Species-specific surveys where the appraisal identifies a reasonable likelihood of presence. An ecological impact assessment setting the residual effects against the step-wise sequence. And a statement of how the scheme delivers net benefit, with the measures identified on a drawing rather than described in prose.

Welsh authorities also expect a green infrastructure statement with most applications of any scale, covering trees, planting, water, access to nature and the connections between them. It is a distinct document from the ecology chapter and it is the one most often missing from a cross-border developer's first submission. A Green Infrastructure Plan covers the same ground, though a Welsh scheme needs the plan checked against the local authority's own green infrastructure assessment.

Where the divergence bites

The practical difference is who carries the uncertainty. In England the number does the arguing: a completed metric showing a gain above the threshold, with a biodiversity gain plan for approval, closes the question. In Wales an officer has to form a judgement on whether your proposals amount to a benefit, and a consultee can reasonably disagree.

That changes how you budget. A Welsh scheme rarely needs a metric run, which saves consultant time, but it usually needs more design work locked into the application drawings, because the benefit has to be visible. Habitat creation shown as a hatched area on a landscape plan, with species mixes, substrate depths and a management regime, is what persuades. A sentence promising improvement at a later stage does not.

Some Welsh authorities ask applicants to run the statutory English metric voluntarily as a way of showing the arithmetic. That is a local preference rather than a requirement, so confirm it in pre-application discussion rather than assuming either way. Each devolved nation has diverged in its own direction, which is why the two tier planning system in Northern Ireland and the hierarchy of developments in Scotland look nothing like the Welsh arrangement.

Survey seasons and the licensing route

Survey windows in Wales follow the same ecology as England, because the species are the same. Bat emergence and re-entry surveys run from May to September with the best results from May to August. Great crested newt environmental DNA sampling is restricted to 15 April to 30 June. Reptile surveys need suitable temperatures between April and October. Breeding bird surveys run through the March to August season.

The licensing route differs. European protected species mitigation licences in Wales are issued by Natural Resources Wales, and the district level licensing arrangements available for great crested newts in parts of England have no Welsh equivalent. Budget for site-specific survey and licensing on a Welsh site with newt potential, and assume a season rather than a few weeks.

Protected species work is one of the areas where a licensed ecologist is legally required. Surveys and any mitigation licence sit under the Wildlife and Countryside Act 1981 and the Conservation of Habitats and Species Regulations 2017, and a draft document is a starting point for that ecologist rather than a substitute for them. A Protected Species Survey draft can set out the method and the policy context, but the survey itself must be carried out and signed by someone suitably licensed.

Securing the measures

Conditions do most of the work. A Welsh authority will normally condition the submission and approval of a landscape and ecological management plan before work starts, with an implementation and maintenance period attached, and a separate condition requiring the measures to be retained.

Where the benefit relies on land outside the application site, or on long-term funding, a section 106 obligation is the usual mechanism. Expect the authority to want a management period long enough to establish the habitat, a monitoring regime with reports at set intervals, and a remedy if the habitat fails to reach the target condition.

Two drafting points save arguments later. Define the target condition by reference to a published habitat description rather than a subjective standard. And agree who signs off the monitoring reports, because an obligation that requires the authority's written approval of each report creates a workload the ecology team may not have.

PlanScope's drafting is grounded in the National Planning Policy Framework and English local plans, so a Welsh application needs the reviewer to check Planning Policy Wales, the relevant Technical Advice Notes and the local development plan before submission. Enter your postcode on PlanScope to see which reports your site is likely to need, then send the draft for professional review.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.