Measuring biodiversity: research into approaches

Recommendations

In this section we will summarise the findings of our review of existing metric and tools, the detailed review of the Biodiversity Metric 3.1 and stakeholder consultations in terms of recommendations for the biodiversity measurement approach for Scotland. This will be split between an overall approach and specific adaptations to Biodiversity Metric 3.1.

It was evident from the overall metric review that there is no one-size-fits all approach to measuring biodiversity. In particular, the tools use a variety of ways to measure biodiversity that are not always comparable or adequately capture the full range biodiversity functions in terms of habitats, species and ecosystem health or functioning. Many of the tools reviewed use proxy measures of biodiversity based on established or modelled relationships between habitat disturbance or land use intensity and species abundance.

1. Recommendation for an overall biodiversity framework

There were both consensus and divergencies in priorities across the four policy areas. To meet the needs of all four sectors, a biodiversity measurement approach or metric will need both common features and some degree of flexibility in its application.

As no single metric or tool meets the needs of all sectors, we recommend that a common framework is developed. This framework should be flexible with respect to the metric or metrics selected, and the tool or protocol used to measure the chosen metric/s. The framework should enable outputs to be tailored to end-use, allow for benefits to be quantified through baselining/benchmarking and permit trading between sectors where desirable.

Our suggested framework is summarised in Figure 1213 and 14. In terms of the four policy sectors considered in this report we would place farm biodiversity audits as requiring the least stringent or robust measurement of biodiversity depending on their relationship to policy and payments. This should still be meaningful but targeted towards participatory monitoring which is achievable with basic training and resources. For example, habitat condition assessment could be qualitative rather than quantitative. More complex approaches would be appropriate for higher tiers of farm payments including outcome based approaches. When qualitative approaches are used, there is a need to demonstrate clear alignment with more quanitative measures.

In contrast, high integrity ecosystem markets such as biodiversity credits would require more robust quantification using a broader selection of indicators to fully capture biodiversity.

Applications to planning and development may fall within this spectrum using a common approach such as an adjusted Biodiversity Metric 3.1, the level of detail and precision required might reflect the scale or impact of development being considered. Impact in this respect could include the distinctiveness or significance of habitats and ecosystems affected by development.

Biodiversity monitoring and reporting has a role in informing and recording indicator data across a range of applications including the three other policy sectors. The degree of complexity of monitoring metrics within the framework would reflect the purpose for collection, who is collecting and the priority of the habitat, species or ecosystem.

The development of monitoring metrics and their associated tools should be an iterative process, involving testing and refinement following feedback to ensure the tools evolve.

The main recommendations related to an overall framework are:

i. To meet the needs of all four sectors, a framework, or standard, is needed that integrates multiple metrics or tools to monitor biodiversity.

ii. This framework needs to provide consistent results, while allowing flexibility in its application so metrics and tools within the framework could be tailored depending on different user or policy needs.

iii. Priority biodiversity indicators include the extent, condition and distinctiveness of habitats; species; ecological connectivity; presence of irreplacable habitat; and ecosystem health and function (see Recommendations 2, 3 and 4 below)

iv. It is important that the approach to biodiversity metrics be accessible, understandable, and flexible in how it is applied across different uses or spatial scales (see Recommendation 6).

v. Biodiversity metrics for Scotland should be clear, concise and transparent, and scientifically robust in terms of measurability (see Recommendation 6).

vi. Biodiversity metrics for Scotland may benefit from certain elements from existing metrics, but existing metrics do not address the full list of priority criteria identified by stakeholders.

vii. With refinement, Biodiversity Metric 3.1 could be adapted for planning and development use, and as part of a wider set of metrics within a biodiversity framework (see Recommendation 8).

2. Habitat and Species Metrics

i. Habitat based metrics should be included, and should characterize extent and condition, and ideally some indication of significance or distinctiveness.

ii. Irreplaceable habitats should be identified and assessed accordingly within the metric (e.g. through the use of strict trading rules, see Recommendations 8.v. and 8.viii below).

iii. Use of different habitat classification systems should be flexible to meet the needs, skills, and training of end-users. Appropriate correspondence tables should be used or developed to allow translation between classifications (e.g. UK Hab to EUNIS). See also Recommendation 8.vi.

iv. Assessments of habitat condition whilst drawing on a common framework should be tailored to meet the needs of different end-users and the objectives of the scenario.

v. Species-based metrics should reflect the presence of indicator species and the diversity of species or taxa. The choice of species should reflect the context in which a metric is being used.

3. Connectivity Metrics

i. Connectivity should be included in the framework. Current metrics include this in different ways, including the modelling based on surrounding land uses and habitat permeability, the presence of features such as linear corridors between habitat patches, or the extent of similar habitats in the surrounding area.

ii. NatureScot have developed a connectivity indicator for Scotland (Blake and Baarda, 2018). However, this is currently produced for four habitats^[38] over 10 large catchments and it may therefore be necessary to expand the range of habitats included and to calculate connectivity at smaller scales, for example to reflect development site contexts. In such instances, existing habitat network modelling (e.g. Buglife's B-Lines, NatureScot's Opportunity mapping) could help target habitat creation to optimise connectivity.

iii. Further research is recommended to determine appropriate connectivity measures across different habitat and land use contexts and scales.

4. Ecosystem function, health, and integrity Metrics

i. Ecosystem integrity, functionality or health should be included. Scotland's Environment^[39]outlines three broad elements included in the Scottish ecosystem health indicators: condition, function, and resilience.

The Scottish ecosystem health indicators may not be appropriate for application in a Scottish biodiversity metric or framework as they reflect a range of nationally available data and report at national scale. But indicators could be selected to reflect condition, health and resilience.

We recommend that suitable ecosystem health indicators should be identified for different habitats and land uses reflecting these three elements. Soil health indicators should be included where appropriate.

ii. Ecosystem health and diversity in an agricultural context should consider the wider system. For example, taking a whole farm approach that includes crop diversity, rotations, management intensity, and abundance of semi-natural or landscape features (these are included in some metrics as indicators of connectivity).

5. Monitoring

i. Chosen metrics or indicators should be amenable to ongoing monitoring or repeated estimation and reflect current and future pressures. This means they should be sensitive to and able to reflect changing impacts.

ii. Scoring systems for future biodiversity should also be sensitive to changing pressures (e.g. climate change, disease and pest risks).

6. Scientific robustness and transparency

i. Chosen metrics or indicators should have a robust scientific basis and provide meaningful measures of biodiversity and/or ecosystem function. They should be clear, concise and transparent, ensuring a standardised framework that allows interrogation to reduce the risk of green-washing or gaming.

ii. The methodology used to estimate biodiversity units should be accessible and published to aid transparency and understanding. This does not preclude the use of proprietary models and tools. Indicator data should ideally be open access. This would aid replicability and ongoing improvement of biodiversity metrics.

iii. Metrics should avoid oversimplification and the requirement to use experienced and trained staff may be unavoidable in some cases. However, light touch approaches, including use of citizen science and participatory monitoring, may be appropriate for applications such as farm biodiversity audits. Guidance and training should be appropriate for the range of users and applications.

iv. Comparability across sectors and habitats would allow for biodiversity uplift to be confirmed across applications. This would also aid tradability.

7. Wider ecosystem services

Wider ecosystem services benefits should be considered. Stakeholders commented on the desirability to include wider ecosystem service benefits within a biodiversity metric framework. We note that this has been captured to some extent by Natural England's Environmental Benefits of Nature (EBN) tool^[40]. The EBN tool is designed to work alongside the Biodiversity Metric 3.1 and provides a qualitative assessment of the impact of net gain actions across a range of 18 ecosystem services, evaluated at 1, 10 and 30 years from implementation. Review of the EBN was outside the scope of this study, but it may be adjusted to reflect Scottish circumstances and applications.

8. Recommendations for adjusting the Biodiversity Metric

Our review of Natural England's Biodiversity Metric 3.1 identified a number of recommendations to ensure it is fit for purpose in Scotland. These are listed in

Table 13 and are summarised below.

The Biodiversity Metric was designed for application in the planning and development sector to explore options to deliver BNG. As such it is not fully applicable to other policy sectors considered in this report. With refinement it would be appropriate for planning and development, and as part of a wider set of metrics. It's user friendly output and familiarity to developers and consultants is beneficial.

i. Ensure that the User Guide/Technical Annexes are fit for Scotland

ii. Create a list of irreplaceable habitats in Scotland. The list of irreplaceable habitats should reflect Scottish circumstances. These should be determined via consultation with industry, regulatory bodies, and ecologists.

iii. Ensure all irreplaceable and Annex 1 habitats are included and correctly accounted for. All Scottish habitats on Annex 1 and the Scottish Biodiversity list should be included in a Scottish Metric and be given a Very High Distinctiveness rating.

iv. Identify a solution ot ensure that peatlands are correctly accounted for (i.e., through consultation with industry and peatland experts). Consultation should help identify a solution for dealing with peatlands in large scale upland developments.

v. Explore the potential to base trading rules on habitat distinctiveness and condition.

vi. Ensure crosslinks between Phase 1 and UKHab are fit for purpose. The UK Hab classification system was favoured by stakeholders as this reflects a known nomenclature and existing experience and training of ecologists. However, not all ecologists are trained in UK Hab, and this nomenclature is not commonly used by the agricultural sector. A Scottish Tool with different interfaces that allow users to switch between classification systems would provide flexibility. However, it is recognised that crosslinking different classification systems can be problematic.

vii. Determine the extent and suitability of existing spatial datasets. Review the accuracy of existing spatial datasets and determine their suitability for use in biodiversity calculations.

viii. Determine appropriateness of all multipliers (i.e., distinctiveness, strategic significance, risk multipliers) (e.g., workshops, expert elicitation). Habitat distinctiveness could be determined using similar/or identical methodologies to those adopted in Metric 3.1. A gap analyses is recommended to determine where spatial data is lacking. Distinctiveness ratings are largely applicable to Scotland, there are, however, instances where these are not appropriate and these should be reviewed by a panel of experts.

With respect to strategic significance, spatial datasets such as opportunity mapping could underpin the development of a standardised reference to spatially target habitat creation. Local strategies have not been formulated with biodiversity accounting in mind, and consequently local authorities may have to review such strategies to ensure suitability.

Due to the variation in environmental conditions across Scotland, average risk multipliers based on habitat type are inappropriate. Greater flexibility in the assignment of risk multipliers to reflect site conditions is recommended. Existing spatial datasets and information on proposed actions could be used to refine risk multipliers.

Spatial risk multipliers are in line with the aims of NPF4 to enhance biodiversity in a way that reduces inequalities. With respect to Scotland, spatial risk multipliers based on Landscape Character Types are more appropriate than those based on Local Authority boundaries. In following natural landscape boundaries, Landscape Character Types are more aligned to landscape scale initiatives. Consideration should also be given to a simple approach that calculates connectivity as an addition to spatial risk.

Consideration should be given to how different risk multipliers (i.e. spatial, temporal and technical difficulty) interact to ensure that the biodiversity units calculated are accurate and incentivise the creation of good quality habitats. We recommend working with practitioners to test a range of realistic scenarios and case studies to ensure that the metric is fit for purpose.

ix. Determine appropriateness of habitat condition assessments (i.e., consultation with habitat experts). Habitat condition assessment approaches were drawn from UK standards and are largely appropriate to Scotland. It is recognised that slight differences may occur, and it is therefore recommended that condition criteria are assessed by habitat experts.

x. Review local strategies to ensure they are suitable to assign strategic significance. Provide guidance to assist in adapting local strategies.

xi. Allow for flexibility in assigning risk multipliers to reflect site conditions and proposed implementation plans.

xii. Explore the potential to integrate spatial datasets to alter risk multipliers to better reflect site specific risks.

xiii. Identify an appropriate means of assigning spatial risk in Scotland.

xiv. Identify means of integrating ecological connectivity into a Scottish Metric (see Recommendation 3 above). Ecological connectivity is considered important to most sectors and should be included in a Scottish metric. Habitat network modelling can help identify opportunity areas to target habitat creation to optimise connectivity. Where such modelling has not been conducted more simplistic approaches could be applied.

xv. Assess Scotland's capacity to deliver on the ground surveys and determine potential skills gap (e.g. surveyors competent in UK Hab, MoRPh River assessment accreditation).

xvi. Assess Scotland's capacity to deliver from a regulatory perspective and provide training and clear guidelines (e.g. UK Hab training, accreditation to conduct MoRPh River assessments).

xvii. Undertake Scotland-wide opportunity mapping for a range of habitats to better account for ecological connectivity.

xviii. Provide different interfaces to allow a range of classification systems to be used.

xix. Provide condition assessment criteria to meet the needs of different sectors and uses. There are differences between existing condition assessments and a standardised approach would help align policy sectors. However, it is recognised that the detail required, and the approach taken, will differ between sectors.

xx. Provide guidance and training to support sectors in tool use and assessments.

xxi. Include management/systems aspects to meet the needs of the agricultural sector. Agriculture takes a systems-approach to land management and consequently aspects relating to management, rotation and spatial/temporal dynamics are important to include to meet the end needs of this sector.

xxii. Consider how species and ecosystem health could be incorporated (see Recommendation 4 above).