Application of the national Red List Index for multiple species groups in Finland


This is an example of where National Red Lists have been used to calculate national RLIs for multiple taxonomic groups (Juslén et al. 2013). The Finnish Red Lists from 2000 and 2010 were used to calculate for the first time the national RLIs for 11 taxonomic groups, following the guidelines of Bubb et al. (2009). The organisms were from different trophic levels and with different life cycles, among others.

The aim of the research was to test the usefulness of the RLI as a tool for measuring changes in conservation status of species at the national level, in addition to evaluating the challenges of applying the method to different taxa and interpreting the results.

Data were used from two Red List assessments of species in Finland, conducted in 2000 and 2010 and following IUCN standards and criteria. The current method of RLI calculation by Bubb et al. (2009) excludes species categorized as EX in the first assessment. The national Red List of Finland does not contain any globally extinct species, but several hundred RE (Regionally Extinct) species are listed. The authors calculated separate RLI values including and excluding the species assessed as RE in both 2000 and 2010. From a national perspective, the authors felt it is reasonable to include RE species in calculations because regional extinction is not necessarily irreversible.

Results of the study showed that the overall RLI of Finnish species decreased, in other words, that in Finland, the represented taxonomic groups were heading toward extinction faster in 2010 than in 2000. However, the RLIs values and trends varied markedly between species groups.

The research demonstrates that different species groups may have different degrees of effect on the overall RLI and are also influenced by different factors. Some examples:

  • Birds: The Finnish bird RLI value declined more steeply than the RLI for any other species groups. The conservation status of many migratory species is greatly affected by processes along their migration routes and in wintering grounds. This needs to be considered when using the RLI to evaluate conservation status at national level.
  • Reptiles and amphibians: There are only 10 species of amphibian and reptile in Finland. There was a genuine change in the conservation status of one species of snake, but due to the low numbers of species, the RLI value and the trend of the group were greatly affected by this one change.
  • Insects: RLI values were calculated for three insect orders: dragonflies and damselflies, true bugs and beetles. Although the three orders are of rather different sizes in terms of species richness and represent a wide range of insect species with very different habitat requirements, it is unclear whether they are representative of insects in general.
  • Due to their short generation length and often good reproduction ability, insects can respond quickly to changes in their environment and colonise suitable areas within their dispersal range. In particular positive changes in species conservation status may thus be observed sooner than in species groups with longer generation length and lower reproduction ability.
  • Improvements in threat status are generally slower than deteriorations and their detectability varies, particularly in species with long generation length.
  • In species with short generation length it can be hard to separate natural variation in population size from an increasing or decreasing trend.
  • Vertebrates are often used to show trends in biological diversity but have only minor effect on the overall Finnish RLI, compared to the higher weight of insects (because of the higher proportion in the species included) in the Finnish RLI.

Conclusions of the authors:

  • An overall RLI should be a more reliable measure of the state of biological diversity than the RLI value of any one species group, but it is still necessary to calculate RLI values for different species groups in addition to the overall RLI to facilitate the interpretation of the latter.
  • Generalizations on the basis of RLIs of a few taxa only may yield a biased view of ongoing trends in the status of biological diversity at the species level.
  • One overall RLI that includes many different species groups may also be misleading if variation in RLI among species groups is not considered and if RLI values are not presented separately for each group.