Temperate Oak (Sessile petraea) woodland at Ariundle NNR, West Highland Area. ©Lorne Gill/SNH.

Natural Capital Asset Index - Official Statistic

https://www.nature.scot/doc/natural-capital-asset-index-official-statistic

The Natural Capital Asset Index is a human-focussed look at how well nature can contribute to people’s wellbeing through a range of ecosystem services and ecosystem characteristics. Natural capital is made up of the environmental resources that combine to yield a flow of benefits to people, such as materials (e.g. food and water), regulating services (e.g. climate regulation and air pollution removal) and non-tangible cultural benefits (e.g. aesthetics and recreation).

Release dates for future publications

February 2027: Natural Capital Asset Index. Email: [email protected]

Current Official Statistic:

Correction Notice

June 2026

The 2025 NACI has been corrected following the discovery of a couple of calculation mistakes:

The 2019 value for the pesticide use (inverse) index, which has changed from 78.22 to 77.3.
The final calculations for the latest year (2022) pulled though the habitat area from 2021, rather than 2022.

The corrected headline NCAI figure changes from 102.8 to 103.0 for 2022.

Where NCAI has been disaggregated by ecosystem service type and habitat, the changes for 2022 range from -0.6 to 0.1 percentage points. A 2 percentage point threshold is used to determine if the long- and short-term differences are increases / decreases or remained stable. Some of the corrected disaggregated results now have different conclusions in relation to this threshold. These are:

Long term cultural services trend has been corrected from stable (+1.8 percentage points) to increase (+2.0 percentage points)
Short term woodland trend has been corrected from stable (+1.4 percentage points) to increase (+2.1 percentage points)
Long term grassland trend has been corrected from stable (1.96 percentage points) to increase (+2.3 percentage points)

The statistic summary, story map, and summary data [add links] have now been updated.

Extra checks are now in place, and we are investigating moving the calculations from Excel to R.

July 2025

The 2025 NCAI has been corrected due to the discovery of an error in woodland extent reported. While we originally reported a 60% increase in broadleaf woodland extent and 0.7% increase in conifer extent since 2000, the real figures are 61% increase for broadleaf woodland and 0.5% increase for conifer. Adjusting these figures resulted in a 0.1 percentage point difference in the overall NCAI figure from 102.9 to 102.8. The error was a combined result of human error and unawareness of more accurate time series data from Forest Research which is backdated according to latest data. NCAI methodology has been updated to ensure this mistake is not repeated.

NCAI Developments

February 2025

Policy relevance to be developed for the Natural Capital Asset Index

The capital asset index (NCAI) tracks the ability of Scottish natural capital to deliver benefits, or ecosystem services. The benefits provided by natural capital can support the success of many Scottish policy areas, ranging from biodiversity to community safety to transportation. NatureScot will be investigating policy specific relevance for each ecosystem service delivered by natural capital so that the ability of natural capital to deliver benefits relating to specific policy areas can be captured. The development of policy specific NCAI results will highlight policy area dependencies on natural capital and enable targeted approaches to support various policy areas through a nature-based approach.

NatureScot has developed an initial list of 36 relevant policy areas, developed from the long list of Scottish policy areas published by the Scottish Government. This list will undergo expert and stakeholder review to determine the relevancy of natural capital to the success of each policy area and, if determined relevant, the degree of relevance of each ecosystem service measured within NCAI. This expert and stakeholder review will be conducted as a workshop in May 2025.

If you would like to take part in the NCAI policy relevancy expert review, please contact NatureScot Economist, Aidan Price, [email protected].

Changes to the Number of Bird Species Indicator Used in the Natural Capital Asset Index

One of the quality indicators used in the Natural Capital Asset Index (NCAI) is the number of bird species. The data for this comes from a summary of the Breeding Bird Survey. Previously, the number of bird species seen was number used for this indicator. For the latest update (February 2025) the list, and hence the number used, was refined.

The refinement was to only use the species recognised on the British Bird List. Where hybrid or subspecies were previously included in NCAI, the update merges these into a single recognised species. Non-native invasive species were also removed.