The NCAI monitors the quality and quantity of terrestrial habitats in Scotland, according to their potential to deliver ecosystem services now and into the future. It is a composite index, based (i.e. equal to 100) in the year 2000. The latest NCAI publication can be found here: http://www.snh.gov.uk/planning-and-development/economic-value/
An evaluation of the NCAI was conducted by experts from the James Hutton Institute (JHI) in 2014 which identified issues with some of the 100 indicators included in the index as well as the methodology used to calculate the NCAI. The full report of the evaluation, which includes a detailed section on the methodology that was used to calculate the index, can be found here: http://www.snh.org.uk/pdfs/publications/commissioned_reports/751.pdf.
SNH have since taken steps to revise the methodology used to calculate the NCAI. The European Nature Information System (EUNIS) land cover classification is now used, while previous versions of the index used the Broad Habitat classifications. The following Scottish habitats are included in the NCAI:
- Inland surface waters
- Raised and blanket bogs
- Woodland and forest
- Unvegetated or sparsely vegetated
- Cultivated agricultural
- Artificial habitats
The first stage of the NCAI’s revised methodology involves an evaluation of each habitat’s potential, if in good condition, to deliver the range of ecosystem services for Scotland. Each ecosystem service is also assessed to estimate its relative contribution to human well-being.
The second stage involves the use of a number of indicators to monitor change in the quality of our habitats (in terms of ability to deliver ecosystem services). An ‘ideal’ indicator is available since at least 2000, is updated regularly and is correlated with natural capital. However, in some instances data availability has been limited and imperfect proxies have been used.