Biodiversity Programme Advisory Group - sub group EH and I indicator: recommendations

6. Expanding the three identified options

Ahead of the sub-group meeting some more detail has been provided for the three options outlined and the indicators within them. In addition, a simple preliminary Strength, Weakness, Opportunity and Threat (SWOT) assessment has been provided for each to aid discussion.

Before going into detail on each of the options it is worth outlining some of the challenges, constraints and questions around selecting indicators for ecosystem integrity and health that need to be accounted for in the groups discussion:

• The set of indicators selected need to be representative of all of the ecosystems in Scotland (terrestrial and marine). This presents challenges as aspects of composition, structure and functionality will vary between ecosystem types.
• The scale and representativeness of indicators will be important to consider. Some indicators will be able to provide a full national assessment at a low resolution (e.g. Nitrogen Balance Sheet), whereas others might only assess certain areas/regions that can be scaled up to be representative of the whole country (e.g. health of protected areas).
• There is a risk that a large number of indicators will be needed to fully represent ecosystem integrity and health which may not align with the resource availability and the desire from the policy unit to have a streamlined set of targets that are not necessarily all inclusive.
• Indicators that already exist or are already committed to be developed in Scotland should be prioritised.
• A combination of approaches from the three options set initially outlined by the PAG should still be a consideration.

6.1 Option 1 - Specific ecosystem health indicators

In the long list provided to the PAG for the March 2024 workshop there were three indicators identified that were deemed specific indicators:

• Delivering healthy ecosystems - This is a redevelopment of the current protected area condition indicator. It will provide greater capability to assess out with protected areas with more of an ecosystem health outcome focus. At the moment it is not set up to provide coverage for all ecosystems nationally
• Services provided by ecosystems - Provides an assessment of services provided by ecosystems using a globally derived methodology.
• Ecosystem red list - International indicator that assesses the status of ecosystems using IUCN defined criteria.

These indicators are either still in development or have not yet been fully applied to Scotland. In addition, while the aim of the Delivering healthy ecosystems approach is to be more widely applicable it is centred on the health of protected areas.

Other indicators have also been identified and/or suggested for further consideration by the NatureScot SAC sub-group that have been developed as specific ecosystem integrity and health indicators. These include:

• The Species Habitat Index – Developed through GEO BON the SHI “measures changes in the estimated size and quality of ecologically intact areas supporting species populations. Ecosystems are made up of species, and as multi-species aggregate, the SHI provide a compound estimate of the ecological quality of natural ecosystems and the health and resilience of species populations.”.
• The Ecosystem Integrity Index – Focuses on forest ecosystems and measures structure (using human modification index), composition (using the biodiversity intactness index) and function (using an index of net primary productivity) with three indices scaled from 0-1.
• Biodiversity Intactness Index – Developed by the Natural History Museum and using the PREDICTS tool the BII is an estimated percentage of the original number of species that remain and their abundance in any given area, despite human impacts. It is averaged across areas (countries, regions or global) to give the remaining biodiversity across that area.

Of these, only the BII has been developed and applied to Scotland as part of the State of Nature (SoN) report.

A SWOT (Strengths, Weaknesses, Opportunities and Threats) assessment for each of these options is outlined in Table 1.

6.2 Table 1 – a simple SWOT analysis of specific ecosystem health indicator options

6.2.1 Indicator: Expanding delivering healthy ecosystems methodology

Strengths:

• Bespoke methodology that is already being developed for Scotland’s protected areas

Weaknesses:

• Would need to be developed for ecosystems that are not within protected areas
• Might not be data availability for all ecosystems

Opportunities:

• Chance to align protected area assessment with wider ecosystem assessment

Threats:

• Large resource and data requirement to implement for all of Scotland’s ecosystems

6.2.2 Indicator: Ecosystem red list

Strengths:

• Methodology already established
• Headline indicators for the GBF and will be developed for Scotland regardless
• Provides flexibility in assessment for all ecosystem types (i.e. different approaches for each ecosystem)
• Includes assessment of integrity (metric for this varies according to ecosystem type)
• Applies to both terrestrial and marine

Weaknesses:

• Still needs to be developed for Scotland
• Unclear on whether assessment of function is included

Opportunities:

• Approach will be developed by Scotland for UK anyway as part of GBF reporting

Threats:

• Large resource requirement to undertake for all in scope Scottish ecosystems

6.2.3 Indicator: Species Habitat Index (NS SAC recommendation)

Strengths:

• Component indicators for the GBF
• Uses available species and habitat data to assess modification, estimated size, quality, fragmentation, and connectivity of ecologically intact areas

Weaknesses:

• Does not assess all aspects of ecosystem integrity (e.g. function)
• Not yet applied to Scotland
• Too similar in approach to species and habitat indicators
• Not applicable to marine

Opportunities:

• [None listed]

Threats:

• [None listed]

6.2.4 Indicator: Ecosystem Integrity Index

Strengths:

• Provides an assessment of the three components of integrity: structure, composition and function

Weaknesses:

• Still in development
• Not yet applied to Scotland
• Not applicable to marine
• Relies on development of other indicators (e.g. human modification index, biodiversity intactness index)

Opportunities:

• [None listed]

Threats:

• Large resource requirement to develop both this indicator and the indicators it uses for Scotland

6.2.5 Indicator: Biodiversity intactness index

Strengths:

• Provides a measure of ecosystem integrity
• Approach has been applied to Scotland within the SoN report

Weaknesses:

• Does not provide an assessment of function
• Only terrestrial ecosystems
• Some issues around intactness classification of modified ecosystems (e.g. non-native coniferous woodland)
• BII suggests 10% increase in UK biodiversity intactness since 1970 which runs counter to all other metrics

Opportunities:

• Opportunity to collaborate with SoN reporting process

Threats:

• Do not have full control over SoN reporting process

6.3 Option 2 - A systems based indicator set

A systems based functionality approach focuses on the flows of energy and materials in and out of ecosystems. This is based on the premise that an ecosystem is of high integrity and health if ecosystems maintain consistent production, nutrient cycles are within natural ranges, carbon stocks are stable or growing, soils and marine sediments are conserved, water quality is high, and river levels avoid extremes . The PAG identified that this could use some of the same indicators that were identified for the Enhancing conditions for nature target topic.

Examples of the indicators available for use that could fit within this framework are (not this is not an exhaustive list):

• Nutrient status - Nitrogen Balance Sheet Scotland – The nitrogen balance sheet offers an annual assessment of the flows of nitrogen in and out of the Scottish economy. Within this is an assessment of inputs from the economy into the atmosphere and hydrophere is undertaken that could be used to assess the health of ecosystems with respect to their nutrient status.
• Carbon status - Greenhouse gas emissions inventory – The Land Use, Land Use Change and Forestry component of the official GHG statistics provides a simple assessment of whether 6 different land use categories are sinks or sources of GHG emissions.
• Freshwater health - Ecological status of rivers – The ecological status of rivers is assessed as part of River Basin Management planning. It provides an overall assessment on the condition of rivers according to ecological, chemical and physical parameters.
• Soil health - Soil health indicators - Preliminary work to develop a suite of soil health indicators has taken place and is now being further developed in the strategic research programme
• Marine health - Clean and healthy seas indicators– Uses a number of indicators (e.g. contaminant concentrations, nutrient enrichment, plastics) to assess the clean and healthy state of Scotland’s seas. These indicators are updates as part of OSPAR and Marine Strategy Framework Directive reporting.
• Ecosystem productivity - Productive and resilient ecosystems – use remote sensing indicators of consistency and stability of primary production over multi-annual cycles for terrestrial, aquatic and marine systems

A SWOT analysis of adopting a systems based indicator set is outlined in Table 2.

6.3.1 Table 2 – A simple SWOT analysis of a systems based functionality meta indicator

Strengths

• Uses already available and established indicators
• Provides a ‘systems based’ assessment of ecosystem function
• Alignment with indicators used for other environmental policy (e.g., climate adaptation and mitigation)

Weaknesses

• Unsure of full coverage of ecosystem functionality components (e.g., soil indicators, other nutrient cycles beyond nitrogen)
• Does not align with GBF approach per se
• Challenge to set target against multiple indicators
• Does not provide an assessment of composition and structure

Opportunities

• Opportunity to develop something for novel Scotland
• Links very closely to Enhancing conditions for nature target topic

Threats

• Each indicator is updated separately and under different ‘ownership’; risk of poor alignment and indicator update

6.4 Option 3 – Other target meta-indicator

A meta-indicator would encompass indicators selection for the other target topics combining as an assessment of ecosystem integrity and health. In its simplest terms if threatened species, habitat condition and extent, citizens and society and enhancing environmental conditions targets have been met then Scottish ecosystems are deemed to be of high integrity and health.

A simple SWOT analysis of this option is presented in Table 3.

6.4.1 Table 3 – A simple SWOT analysis of a meta indicator using the other target indicators

Strengths

• Does not require additional indicators

Weaknesses

• Not a full reflection of ecosystem integrity and health components (e.g., function)
• Unclear currently how a target could be set using this approach
• The oversimplification inherent in meta-indicators may make interpretation and messaging confusing
• Weighting of components can be controversial

Opportunities

• The Planetary boundary approach (Richardson et al. 2023) may offer a practical meta-indicator that also encompasses flows, but it would require substantial work to develop a Scotland version

Threats

• High dependence on maintenance and updates of all other indicators