NatureScot has published an issues paper for consultation as the next stage of developing a biodiversity metric in Scotland.


With the introduction of NPF4's Policy 3(b) just over a year ago, major, national and EIA developments are all required to demonstrate significant biodiversity enhancements as part of the proposed development. However, there have been different approaches from different authorities in applying the policy. While some authorities have taken a flexible and qualitative based approach, others have sought a percentage increase based on the DEFRA biodiversity metric that is applied in England.

The Scottish Government has previously assessed the English metric and its applicability in Scotland. The conclusions of that assessment considered that while the English metric had merit, it was not directly transferable, and a Scottish metric would need to be developed.

NatureScot was therefore tasked with developing a Scottish biodiversity metric based on adapting the metric used in England to Scotland's environmental, policy and legislative context.

NatureScot's proposed approach to developing the metric will be in two phases. Phase 1 seeks to establish the foundations of the metric. Phase 2 will then review the tool’s components. This consultation is the first opportunity for stakeholder engagement in the process.

The Consultation

The Consultation was published on 10 April 2024 and seeks stakeholder input on what NatureScot has identified as the key issues, the English position thereon and NatureScot's thoughts on how the issue should be addressed in Scotland These are set out briefly below:

Key issue

English metric position

NatureScot thoughts

The principles and rules underpinning the metric's approach

The metric is underpinned by a series of rules, principles and working practice guidance governing its application to development proposals.

The underlying principles, rules and working practices of the English metric will need to be reviewed for their applicability in Scotland.

The habitat classification system

The metric operates through the classification of individual habitats, with which the biodiversity "units" of a site are calculated.

NatureScot needs to understand the appropriate habitat classification system for use in Scotland and ensure there is effective translation between the systems, where required.

Irreplaceable Habitats

England’s metric identifies certain habitats (e.g. ancient woodland, blanket bog, limestone pavements etc.) as irreplaceable. Any loss of irreplaceable habitats is to be considered separately outwith the metric.

There is no formal list of irreplaceable habitats in Scotland and therefore these will need to be identified. It will also be necessary to assess if the English metric's approach to such habitats should be followed in Scotland.

Habitat Distinctiveness

The approach and criteria used to calculate distinctiveness varies with habitat types classified in the metric.

While the general approach is considered transferable, the "habitat types" applied would need to be assessed to identify any gaps (i.e. missing habitat types) for the Scottish context.

Habitat Condition

A habitat's condition will be assessed against its ecological optimum state.

The assessment criteria and method will need to be reviewed to ensure they are appropriate for Scotland.

Strategic Significance

The local significance of a particular habitat is assessed based on a "Local Nature Recovery Strategy" (or an alternative strategy where an LNRS is not published).

There is no direct comparable for an LNRS, but there are other strategies that could be relevant in Scotland (e.g. Local Biodiversity Action Plans). Some flexibility is acknowledged in what strategies/plans will be important for a habitat's significance.

Technical Difficulty Risk Factor

The metric accounts for uncertainty in the effectiveness or technical difficulty of creating / enhancing habitats through a risk multiplier based on an "average" assessment of the relevant habitat.

The approach to assessing technical difficulty and the application of multipliers will need to be reviewed. There is also scope to consider greater flexibility in the risk assessment.

Temporal Risk Factor

The average time it takes for a created or enhanced habitat to achieve a target condition is factored in through a multiplier (the longer the time, the lower the multiplier).

As a more varied landscape (e.g. elevation, exposure, soils), Scotland may require greater flexibility in assessing the time multiplier, based on specific conditions.

Spatial Risk Factor

On-site delivery is the focus of the metric, and proposals with off-site delivery, including sites outwith the planning authority's boundary are "penalised".

On-site shall be the preference in Scotland. As Scotland's authority areas are generally larger than in England, the approach to off-site delivery will potentially need to be re-drawn.

Send them homewards?

Biodiversity is a complex and multifaceted beast and any metric will only ever be able to go so far - a generally applicable metric cannot cater for diversity on both the macro and micro levels at the same time. It's always going to have its shortfalls given the inherent limitations of a quantitative approach to biodiversity, and it's always going to have a mixed response.

However, generally, the development of a metric is a useful tool for both developers and planners, providing greater certainty on how to ensure biodiversity enhancements are incorporated into new developments.

What is encouraging from the issues paper published for consultation is the acknowledgement by NatureScot that the metric needs to incorporate some elements of flexibility in the application of the parameters and approach (at least in comparison to the English metric). While some may see this as adding uncertainty (or perhaps complexity) into a tool that is meant to provide greater certainty, a more positive perspective may be that it demonstrates an acknowledgment of the complexity of the issue and the diverse landscapes and wildlife of Scotland, having considered where the English metric may not suit Scotland.

Getting involved

The Consultation seeks views on the key issues identified and whether there are other issues with the English metric that need to be considered as part of the process. Any solutions to the issues raised are also welcome.

The Consultation closes on 10 May 2024.