Description:

This indicator is based on trends for combinations of Scottish species in order to reflect the overall status of Scottish biodiversity across marine and terrestrial (including freshwater) habitats.

Performance is assessed based on three measures:

  • Index of abundance of marine species
  • Index of abundance of terrestrial species
  • Index of occupancy of terrestrial species.

Source of Data:

The data for this indicator are gathered from the publication “Marine and Terrestrial Species Indicators“, a new experimental official statistics product by NatureScot. Updates to this indicator can be found on the NatureScot official statistics webpages.

Data on individual species come from a variety of sources, principally:

  • Abundance-based data generated by well-established national monitoring schemes. For marine species, only data on seabirds is used.
  • Occupancy-based metrics using more ad hoc presence-only biological records. Following several years of development and refinement of methods to produce such trends at the UK scale (e.g. Outhwaite et al. 2018), trends for the UK’s four constituent countries have been produced by the UK Centre for Ecology and Hydrology (UKCEH; previously the CEH). Where data is available for both abundance and occupancy for a particular terrestrial species the abundance data is used.

Further details on sources is provided in the NatureScot publication. The great majority of the contributing data sources are collected through the efforts of expert and dedicated volunteer surveyors and recorders, without whom our knowledge of biodiversity in Scotland would be much poorer, and this indicator would not be possible.

A report describing the background to this indicator was published by Scottish Government in March 2021.

Definitions:

Abundance trends reflect changes in the number of individuals of a species,

Occupancy trends are based on the number of sites where a species is present, reflecting the size of the range within which it is found, and can be less sensitive to change than measures of abundance.

Terrestrial species include freshwater species.

Criteria for Change:

The performance arrow for this indicator is assigned based on the performance of all three measures:

  • If one or more  measures are decreasing, then a performance worsening arrow is assigned.
  • If one measure or more measures is increasing whilst any other(s) is(are) stable, a performance improving arrow is assigned.
  • Otherwise a performance maintaining arrow is assigned.

In order to determine whether the individual measures are increasing, decreasing, or stable, the symmetrical thresholds below are used. If the recent change in the figure is less than the value of this threshold, performance is considered to be stable.

  •  Index of abundance of marine species:  5 per cent

  • Index of abundance of terrestrial species: 6 per cent

  •  Index of occupancy of terrestrial species:  1 per cent

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