Local nature recovery strategies and the metric multiplier

The strategic significance multiplier is the one part of the statutory biodiversity metric that rewards where you put a habitat rather than what you build. A habitat formally identified in a local nature recovery strategy attracts a higher multiplier than the same habitat in the same condition somewhere the strategy says nothing about, which means the mapping published for your area can change the number of units a scheme delivers without changing a single plant.

For a planning consultant assembling a biodiversity gain plan, that makes the local nature recovery strategy a document to read at layout stage, not at submission.

What a local nature recovery strategy is

Local nature recovery strategies were created by Part 6 of the Environment Act 2021. Every part of England falls within one, prepared by a responsible authority appointed by Defra, usually a county council, a combined authority or a unitary authority working across a wider area.

Each strategy has two components. A statement of biodiversity priorities, which sets out what the area is trying to achieve. And a local habitat map, which identifies areas of particular importance for biodiversity and areas where the recovery or enhancement of habitat could make a particular contribution.

That second element is the one the metric reads. The strategy is not a development plan document and does not allocate land, but local planning authorities must have regard to it, and many have begun to reference it directly in their own biodiversity policies.

How strategic significance works in the metric

In the statutory metric, habitat units are a product of area, distinctiveness, condition and strategic significance. The first three describe the habitat. The fourth describes its location against local priorities.

The metric offers three categories. The highest applies where the habitat is in a location formally identified in a local strategy, with a multiplier of 1.15. The middle category covers locations that are ecologically desirable but not identified in a local strategy, at 1.1. The lowest, at 1.0, applies where the location is neither. Check the current published version of the statutory metric before relying on those figures, because the tool and its guidance have been revised since mandatory net gain began.

The effect compounds. A 15 per cent uplift on the post-development units of a large habitat parcel can be the difference between a scheme that reaches the mandatory 10 per cent gain on site and one that has to buy off-site units or statutory credits.

It works in the other direction too. Baseline units are also multiplied, so a site that already sits in a priority area starts from a higher baseline and is harder to improve upon. That asymmetry catches people who think of the multiplier purely as a bonus.

Finding the mapping for your area

Start with the responsible authority, which publishes the strategy and its local habitat map. Most publish an interactive viewer alongside the document, and several have made the spatial data available for download so an ecologist can overlay the site boundary directly.

Three things to record when you look it up:

• The publication date and version of the strategy, because an early draft carries no weight in the metric.
• Whether the site falls within an area of particular importance, an area of opportunity for recovery, or neither.
• The specific priority the mapping attaches to that area, which is what the gain plan narrative has to engage with.

Take a screenshot with the site boundary visible and date it. Reviewers ask.

Designing to capture the multiplier

The multiplier rewards habitat in the right place, which means it is a layout question rather than a planting question. Three moves do most of the work.

Put the largest habitat parcel where the strategy says the opportunity lies. On a site where the mapping identifies a river corridor, a wide riparian buffer earns the multiplier on a long, thin parcel that would otherwise have been mown amenity grassland.

Match the habitat type to the stated priority. A strategy identifying species-rich grassland restoration does not reward a wildflower-seeded strip created as a visual feature with no management regime behind it. The metric's condition assessment and the 30-year management commitment are what make the habitat real, and habitat monitoring reports over the 30 year period is where that commitment lands.

Connect the parcel to something. Strategies routinely identify connectivity as a priority, and a hedgerow or buffer that links two existing features reads very differently from an isolated patch.

Where strategies are not yet published

Not every strategy is final, and drafts have been consulted on at different points across England. Where there is no published strategy for your area, the metric's middle category is still available: a location that is ecologically desirable, even without formal identification, attracts the 1.1 multiplier.

That category needs an ecologist's reasoned justification rather than a map reference. What supports it is a statement tying the proposed habitat to something documented: a local wildlife site nearby, a priority habitat inventory record, a species assemblage identified in the Preliminary Ecological Appraisal, or a catchment plan.

Say which category you have claimed and why, in the gain plan, in one short paragraph. Unexplained use of 1.1 across every parcel is the first thing a reviewing ecologist queries.

Interaction with local plan policy

Authorities are increasingly writing the strategy into policy, and the wording varies in how hard it bites. Some require development to contribute to the priorities identified for the area. Some simply require regard to be had to them. A few set a higher percentage net gain than the statutory 10 per cent, which is a separate policy question from the multiplier.

Read the adopted policy and any supplementary document together with the strategy. Where a policy requires contribution to a mapped priority and the scheme ignores it, the multiplier is the smaller of your problems.

There is also an honest uncertainty worth stating. Strategies are new, and how much weight decision-makers give the mapping where it conflicts with an allocation in an adopted plan has not been worked through in many places yet.

An illustrative example

A consultant is working on a 4 hectare edge-of-settlement allocation. The local habitat map identifies the western field boundary as part of a wider opportunity area for hedgerow restoration and connectivity. The layout is amended to retain the existing hedge, widen the margin to 10m, and plant a new native hedge along the new western boundary rather than erecting close-boarded fencing. The metric run with those parcels in the formally identified category produces enough post-development units for the scheme to meet the 10 per cent requirement on site. This example is illustrative and the outcome would differ on another site.

Explaining the uplift in the gain plan

The biodiversity gain plan is approved by the local planning authority after permission is granted and before development begins, so the strategic significance claim has to survive a technical read without the author present.

A short, specific passage does the job:

1. The strategy, its responsible authority, its version and publication date.
2. The mapped designation the site or parcel falls within, with an extract showing the boundary.
3. The priority the mapping attaches to that area, quoted or closely paraphrased.
4. Which parcels have been assigned which strategic significance category, and why.
5. How the 30-year management regime delivers the priority rather than merely the habitat type.

The statutory metric is to be completed by a competent person, and the gain plan has to be approved by the local planning authority. A Biodiversity Net Gain Assessment drafted in advance gives that competent person a structured starting point, and nothing more than that: the metric calculation, the condition assessment and the management commitments require professional ecological judgement and in some cases a licensed ecologist.

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