Measuring biodiversity: research into approaches

Metric 3.1 Appraisal: Conclusions

The need to develop a standard means to account for biodiversity in Scotland is recognised across stakeholder groups. Metric 3.1 provides a potential framework that has undergone significant testing and reviews in England. With refinement, Metric 3.1 is largely applicable for use in the Planning Sector in Scotland and several companies are using adapted versions of Metric 3.1 in Scotland to them to account for biodiversity during site development. Current users provide key insights into useability and potential adaptions. With strong alignment between Planning and Natural Capital, following adaptions this metric would be fit for purpose for both sectors.

To ensure that multipliers and habitat condition assessments are appropriate for use in Scotland, we would recommend these are comprehensively reviewed by a team of stakeholders including ecologists with experience of specific habitat types. The integration of different multipliers can result in inappropriate results. For example, incentivising the creation of poorer quality habitats, or penalising action to restore a low distinctive habitat to a higher distinctive habitat. Industry have also indicated that, when integrated, the risk multipliers can be over cautious. In an example considering intertidal habitats, West et al (2022) found that 10% BNG required substantially larger areas of habitat creation in comparison to compensation for habitat loss under the Habitats Regulations where a simple ratio of area of habitat created to habitat lost of 2:1 was considered acceptable. There is therefore a need to review how risk multipliers interact, to ensure that the biodiversity units calculated are appropriate and incentivise the creation of good quality habitats. We therefore recommend that any Scottish metric is tested by practitioners, exploring a range of realistic scenarios and case studies to ensure that it is fit for purpose.

With respect to future improvements, risk multipliers in Metric 3.1 are currently set as average values based on habitat type. It is recognised that environmental conditions vary considerably across Scotland, and that site specific factors such as elevation, deer densities, soil type, hydrology could be taken into account. Additionally, aspects relating to implementation and management plans for habitat creation and/or enhancement could also be considered when accounting for risks.

For use outside of the planning sector, it would be essential that all irreplaceable and Annex 1 habitats are included and correctly valued in a Scottish metric. If future uses in Scotland, were to expand to the Agricultural and Conservation sectors further refinements would be required particularly when it comes to condition assessments. For agriculture these should allow for farmer-friendly participatory monitoring, include condition assessments for cropland and reflect system-based approaches such as rotation, and management.

The outputs derived from a Scottish metric should be widely accessible, however, to meet the needs of different sectors a Scottish tool would have to accommodate different levels of ecological expertise. From more detailed assessment targeted to the planning and conservation sectors, to participatory approaches targeted to the agricultural sector. This could be achieved through different interfaces, or a suite of tools targeted to different sectors and uses. This would allow us to utilise current tools under development (e.g. NatureScot's POBAS scorecards).

There is huge potential for trading of Biodiversity Units between sectors. To foster this a common currency is needed. This could be achieved through having a single metric with different interfaces, aligning the calculation of biodiversity units across tools, or using the biodiversity equivalent of an exchange rate. We need to however consider how sector specific tools could align to provide a common currency for Biodiversity.

Stakeholders in Scotland highlighted the importance of including ecological connectivity in a Scottish metric and this fits with Scottish Government's ambitions to create Nature Networks across Scotland. Connectivity could be integrated within a Scottish metric using opportunity mapping where available, expert judgement and proximity to existing habitats. Additionally, ecosystem health was identified as a priority across sectors and there is a need to identify how this could be integrated into a Scottish metric.

Overall, our findings indicate that with refinements the Natural England Biodiversity Metric 3.1 would meet the needs of the Scottish planning sector. A range of refinements are recommended which vary in ease of implementation and urgency with some recommendations deemed necessary prior to release, while others are deemed desirable in the longterm (

Table 13). Similar to the Natural England Metric 3.1, a Scottish metric would have to be tested and validated and be adaptable, and evolve based on user-feedback. Following release regular consultation and reviews are therefore recommended.

Outside of the planning sector, a suite of sector specific tools would help ensure greater functionality. The metrics that these tools measure should be underpinned by science, and ground truthed, whilst ensuring that growth and development is not unduly stifled. Outputs should be accessible to all and calculations transparent to prevent the risk of green washing. The metrics adopted should have a means of standardising Biodiversity units across sectors to permit and encourage trading between sectors.

H - Urgency high: prior to release - High difficulty

I - Urgency medium <3 years - Intermediate difficulty

E - Long term 3+ years - Relatively easy