Wales: the biodiversity duty under the Environment Wales Act

The biodiversity duty in Wales planning comes from section 6 of the Environment (Wales) Act 2016, and it is not the same thing as English biodiversity net gain. There is no statutory percentage, no mandated metric and no biodiversity gain plan to be approved. Instead, every public authority in Wales, including every local planning authority, must seek to maintain and enhance biodiversity so far as is consistent with the proper exercise of its functions, and in doing so must promote the resilience of ecosystems. That duty applies to the act of determining your application.

This article deals with Wales only. An English scheme runs on a different regime entirely.

What the section 6 duty requires

The duty has two limbs and both matter. Maintaining and enhancing biodiversity is the familiar part. Promoting the resilience of ecosystems is the Welsh addition, and it changes what an authority is looking for in your evidence.

Section 7 of the same Act requires Welsh Ministers to publish lists of living organisms and types of habitat of principal importance for maintaining and enhancing biodiversity in Wales, and authorities must have regard to those lists. They replaced the earlier English and Welsh lists under the Natural Environment and Rural Communities Act 2006 for Welsh purposes.

The duty also bites on the authority itself. Public authorities in Wales must publish a plan setting out how they intend to comply and must report on what they have actually done at intervals of no more than three years. Those reports are public, and they are a useful source when you need to understand what a particular authority says it is trying to achieve. A council whose section 6 report commits it to improving connectivity along a named river corridor has told you what to design towards.

Net benefit for biodiversity in practice

Planning Policy Wales requires development to provide a net benefit for biodiversity, applied through a step-wise approach. Avoid harm first. Where harm cannot be avoided, minimise it. Where it cannot be minimised, mitigate it. Only then compensate, and enhancement sits on top.

The absence of a metric is the practical difference from England. Net benefit in Wales is a judgement reached on evidence rather than a number generated by a calculator, which cuts in two directions. There is no arithmetic threshold you can fail, and there is no arithmetic result you can point to that closes the argument. Case officers and their ecological advisers assess whether the scheme leaves the site better than it found it, using habitat condition, species interest and the resilience attributes.

So the submission has to make the case in words and drawings rather than in a spreadsheet. A planting schedule, a habitat plan showing before and after, and an account of how the proposal strengthens the wider network will do more than an asserted percentage.

Welsh Government has consulted on more prescriptive approaches over time. As at the date of this article, net benefit remains a policy requirement rather than a statutory metric-based duty, and the position should be confirmed on gov.wales before relying on it.

Resilient ecological networks and connectivity

Ecosystem resilience in Wales is assessed against a set of attributes: diversity, extent, condition, connectivity and adaptability. They come from the Welsh natural resources framework and they appear in Planning Policy Wales, in Natural Resources Wales advice and in local plan policy.

Connectivity is the attribute that most often shapes a layout. A development that retains a hedgerow but severs it at the access point has reduced connectivity even if the total hedgerow length is unchanged. Authorities look for retained and strengthened linear features, permeability for species through boundaries, dark corridors free of lighting spill, and connections to habitat beyond the red line.

Three design responses carry weight.

1. Keep boundary features continuous and show the crossing points, with culverts or mammal gaps dimensioned rather than described.
2. Plan the external lighting around the ecological corridors rather than fitting the corridors around the lighting, and show the isolux contours.
3. Connect retained habitat to habitat off site, and evidence what is there with a desk study rather than assuming.

Adaptability is the attribute most often ignored. It asks whether the habitat you are creating can cope with a changing climate, which means species choice, water availability and long-term management rather than a planting plan drawn for year one.

Evidence expected with an application

The baseline document is an ecological appraisal prepared to the standards of the Chartered Institute of Ecology and Environmental Management, covering a habitat survey, a desk study of designated sites and records, and an assessment of the likelihood of protected species being present.

Protected species law is not devolved in the same way. The Wildlife and Countryside Act 1981 and the Conservation of Habitats and Species Regulations 2017 apply in Wales, so bats, great crested newts, dormice, otters and the rest are protected on the same statutory basis. The difference is administrative: European protected species licences in Wales are issued by Natural Resources Wales rather than Natural England, and the licensing policies and forms differ.

Survey seasons are the same because the ecology is the same. Bat emergence surveys run from May to September, great crested newt environmental DNA sampling runs from 15 April to 30 June, reptile surveys run April to October. A Welsh scheme that misses a season loses the same year an English one would.

Many Welsh authorities also expect a green infrastructure statement with applications above a stated size, setting out how the scheme contributes to the green and blue network. Check the authority's validation list, because the threshold and the required content vary.

One further Welsh difference affects the drainage design directly. Schedule 3 to the Flood and Water Management Act 2010 was brought into force in Wales, so sustainable drainage approval from the SuDS Approving Body is mandatory for construction work with drainage implications above the stated area threshold. That approval is separate from planning permission, and the SuDS design and the biodiversity design have to be developed together rather than sequentially.

Who prepares it and who signs it off

There is no statutory competent person regime for net benefit in Wales equivalent to the English biodiversity gain plan arrangement. In practice the authority's ecologist, or an ecological adviser retained by the authority, reviews the submission, and they expect a suitably qualified ecologist to have prepared it.

That means a member of the relevant professional institute with demonstrable experience of the habitats and species involved, and, where a licence will be needed, a surveyor who holds the relevant class licence or registration. Surveys and mitigation licences for European protected species require a suitably licensed ecologist as a matter of law, and an AI-assisted draft is a starting point for that professional rather than a substitute for the survey work.

Name the author, state their qualifications and state the survey dates. An undated survey is treated as no survey, and a survey more than about two or three years old will usually need updating.

Conditions and management plans

Expect the net benefit to be secured by condition rather than by obligation in most cases. The usual package is a construction environmental management plan with a biodiversity section, a landscape and ecological management plan covering a defined period, and a lighting condition tied to the submitted isolux drawing.

Write the management plan with a funding and responsibility mechanism, because an authority discharging the condition will ask who maintains the habitat in year ten and where the money comes from. On larger schemes that question moves the obligation into a section 106 deed with a management company and a commuted sum.

Monitoring is the part developers under-budget. A management plan with a stated monitoring regime and remedial triggers is far easier to discharge than one that simply describes an intended end state.

Where the Welsh position differs from England

The headline differences are worth holding in mind on any cross-border portfolio. Wales has a duty on authorities and a policy requirement for net benefit, while England has a statutory 10 per cent gain, a prescribed metric and a biodiversity gain plan approved by the authority. Wales assesses resilience attributes and England assesses metric units. Wales has mandatory SuDS approval through a separate body and England does not. Licensing in Wales runs through Natural Resources Wales.

That divergence runs through the devolved systems generally, from Scotland's hierarchy of developments to Northern Ireland's two-tier arrangement, and a document written for one nation rarely transfers to another without rework.

PlanScope's drafting is grounded in English national policy and English local plans, so a Welsh application needs the reviewer to check Planning Policy Wales, Technical Advice Note 5 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. For specialist technical reports, qualified professional input may be required. You can browse the report types by category or start from a postcode.