Measuring biodiversity: research into approaches

This report considers methodologies for measuring biodiversity at site-level for use in Scotland.

Results: Metric 3.1 across sectors


The Metric 3.1 is designed specifically for use in the Planning and Development Sector. This section therefore explores how well suited Metric 3.1 to use outside of the Planning and Development sector. We will evaluate its fitness for use across three policy areas; Agriculture, Conservation and Biodiversity Monitoring, and Natural Capital Markets. We will focus on the needs of different sectors and the policy and legal frameworks that underpin requirements. This section focusses specifically on where adaptions to Metric 3.1 would be requied to ensure fitness for use outside of the Planning and Development sector. With strategic significance and risk multipliers standardised across sectors, no further adaptions would be required and they are not considered further.

Trading rules, irreplaceable habitats, and distinctiveness: Across sectors

Above we highlight that because Metric 3.1 is primarily designed for the Planning and Development sector irreplaceable and Annex 1 habitats are not adequately distinguished and accounted for. In this sector these habitats are identified during the initial Ecological/Environmental Assessment and require bespoke compensation in line with existing policy and legislation. If a Scottish Metric was applied to other sectors all irreplaceable habitats and Annex 1 habitats would need to be correctly valued. For example, currently Metric 3.1 does not include ancient woodland as a habitat in its own right, such information would be crucial to undertake a natural capital of an estate. For consistency, it is recommended that all habitats of conservation concern are 1included within a Scottish metric. The section above on trading rules in the Scottish context considers approaches to developing trading rules.

Key insights and recommendations – trading rules

  • Recommendation 3. Properly accounting for irreplaceable and Annex 1 habitats would be an essential requirement if Metric 3.1 was to be fit for purpose outside of the Planning and Development sector.

Habitat classification: Across sectors

UK Hab is the primary system to classify terrestrial habitats in Metric 3.1. This system is widely used by ecologists and directly relates to UK Biodiversity Plan Priority Habitats and thus the terminology is familiar to most sectors. Furthermore, UK Hab typically provides more user-friendly descriptions of habitats to non-experts than EUNIS – for example, UK Hab L4 Modified grassland relates to EUNIS L3 Permanent and mesotrophic pastures and aftermath-grazed meadows.

While EUNIS is widely used across Europe, and by NatureScot, participants from both the Conservation and Biodiversity Monitoring sector and Planning and Development sector expressed concerns in adopting EUNIS over UK Hab. For example, one comment from the Planning and Development stakeholder group was "It is important to stick with a classification approach that ecologists are familiar with - many have already switched to using UK Hab as standard. Very unusual for ecological consultants to use EUNIS, so would recommend avoiding a change to EUNIS". This is supported by the findings of our online stakeholder poll which indicated that UK Hab was the preferred classification system for three out of four sectors; with the agricultural sector indicating that none of the classification systems were appropriate (although there was a poor response to this question) (Annex 5 Figure 18Figure 18b). To increase uptake in the agricultural sector, consideration should be given to also including an alternative habitat classification system that this sector are more familiar with (e.g. classifications used in Farm Environment Maps[37]).

Providing flexibility in the classificaiton system used, would help meet the different needs across sectors. Crosslinking different classification systems is, however, complex, and can result in habitats being misclassified (see above). There is therefore a need to ensure that crosslinks between different classification systems give sensible results.

Key insights and recommendations – habitat classifications

  • Recommendation 18. A Scottish tool with different interfaces to allow users to switch between classification systems would provide flexibility. However, it is recognised that crosslinking different classification systems can be problematic.

Habitat Condition: Across Sectors

Here we explore how appropriate habitat condition criteria are across our policy sectors. Additionally we cross reference Metric 3.1 condition assessments with other assessments currently being developed in Scotland.

The criteria used to assess habitat condition will vary between sectors. The Conservation sector are likely to use the tool for site condition monitoring of statutory sites designated through UK legislation and international agreements. This monitoring would require specialist ecological input and would need to align directly with JNCC's Common Standards Monitoring - thus requiring greater detail than is captured in Metric 3.1. The agricultural sector, on the other hand, would favour participatory approaches that engage land managers and promote adaptive management. For this sector, condition assessments would need to be easily undertaken by non-experts following basic training, yet they should still accurately reflect habitat quality. NatureScot's Piloting an Outcomes Based Approach in Scotland (POBAS) could provide important insights into how this balance can be met. For rivers the MoRPh citizen science component could provide appropriate assessment criteria for the agricultural sector.

Even within a sector the appropriate level of detail will vary depending on the tool use. Use in the Natural Capital sector may vary from robust baselining of biodiversity to enable the selling of biodiversity units, or alternatively a cruder approach could be adopted using remote sensed data to provide a rough estimate of Natural Capital stocks. Similarly, in the agricultural sector a baseline biodiversity audit is likely to focus on type and extent of habitats - in such instances average habitat condition scores could be applied as with Natural England's Small Site Metric 3.1. Whereas when dealing with Outcome Based Approaches to Agri-environment and Climate Schemes, more detailed assessments would be required to accurately reflect habitat quality.

With respect to the agricultural sector, condition assessment criteria align relatively well with forthcoming assessments (i.e. habitat score cards under development in POBAS and NatureScot's Natural Capital Assessment trial). For example, criteria for Grasslands of Low Distinctiveness are similar to NatureScot's Natural Capital Assessment. The later, however, also includes additional criteria relating to soil health and grassland management. Similarly, the criteria for Hedgerows also overlap with NatureScot's POBAS scorecard with respect to hedgerow structure, however, there are differences. Metric 3.1 includes criteria relating to the vegetation at the base of the hedgerow while NatureScot's scorecards include aspects relating to management (e.g. cutting frequency and inclusion of bird boxes). In some instances, condition criteria do not align well with forthcoming assessments. For example, criteria to assess Heathland condition deviate considerably from those in NatureScot's Natural Capital Assessment. It is important to note that the above NatureScot assessments are in development and may change based on trials and feedback.

Metric 3.1 does not provide any condition criteria for Arable or Horticultural land, including field margins, intensive orchards and temporary grass and clover leys. Arable field margins are included in the Scottish Biodiversity List highlighting their importance to biodiversity. Furthermore, these habitats provide ecosystem services that underpin food production (e.g. pollination services, natural pest regulation). The inclusion of condition criteria for Arable and Horticultural land would be fundamental for the agricultural sector and these could align with POBAS scorecards, and NatureScot's Natural Capital Assessment. The food production value of arable and horticultural land will help to ensure that increasing the biodiversity potential of this habitat will not result in direct competition with semi-natural habitats.

Key insights and recommendations – habitat condition

  • Recommendation 19. Different condition assessment criteria would be required to meet the needs of different sectors and uses within a sector. In some instances, the use of average condition scores may provide an alternative to on the ground assessments.
  • Recommendation 20. Provide guidance and training to support sectors in tool use and in conducting on the ground surveys.

Building on Metric 3.1: Across sectors

Our stakeholder workshop indicated that ecological connectivity was the most important landscape aspect to consider for the Planning sector and alongside ecosystem health it was also of primary importance to the Natural Capital and Conservation sectors (Annex 5 Figure 18c). Enhancing ecological connectivity and promoting habitat diversity will require key stakeholders to work together to co-design landscapes that work for biodiversity and people. A common framework will help to align different policy sectors, allowing different funding streams to be integrated to ensure benefits are maximised.

Stakeholder workshops highlighted that farmland cannot simply be viewed as individual land parcels and agriculture very much adopts whole systems approaches. A diversity of different management practices impact on biodiversity including crop rotation, use of agro-chemicals, tillage practices, frequency and timing of operations, drainage and grazing management. These factors influence habitat condition and can enhance both spatial and temporal heterogeneity within the landscape. Metric 3.1 does not consider management practices and rotation, but they are considered in NatureScot's POBAS and Natural Capital Assessments. To ensure that a Scottish metric meets the requirements of the agricultural sector, system-based aspects and criteria to assess the condition of cropland should be included.

Workshops also identified ecosystem health as a priority to all sectors and indicator/priority species as a priority to the Conservation sector (Table 2). Future development of a Scottish metric should consider how these aspects could be incorporated.

Key insights and recommendations – landscape structure and systems

  • Recommendation 21. Account for system based approaches to meet the end needs of the agricultural sector.
  • Recommendation 22. Consider how aspects relating to species and ecosystem health could be incorporated within a Scottish metric.



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