Indicator framework for measuring quantity and quality of biodiversity—Exemplified in the Nordic countries

In 2002, world leaders made a commitment through the Convention on Biological Diversity (CBD), to achieve a significant reduction in the rate of biodiversity loss by 2010. At the Conference of the Parties of the CBD in Nagoya, Japan in 2010, the target was renewed for 2020. We have developed a Biodiversity Change Index (BCI) to help measure progress towards this target. The BCI is constructed with a two-dimensional resolution, allowing for a direct evaluation of the relative importance of changes in quantity and quality, respectively, to the overall change in biodiversity. Quantity is measured as the area of a specified habitat type and quality as the abundance of indicator species and other habitat quality parameters, such as the proportion of old trees or dead wood in forests. The BCI enables easy comparison of changes in biodiversity between different habitat types and between different regions and nations. We illustrate the use of BCI by calculating the index for the Nordic countries for two common habitat types, farmland and forest, and one habitat type of similar importance in the northern hemisphere; mires. In the period 1990–2005 declines in biodiversity of similar magnitudes are seen for farmland and mires across the Nordic countries, while for forest, trends vary considerably. Our results show that the BCI framework can be a useful tool to communicate the complex issue of biodiversity change in a simple manner. However, in accordance with other studies of biodiversity change we conclude that existing monitoring data are too scarce to consistently calculate BCI for all habitat types in all Nordic countries. In order to reasonably evaluate changes in biodiversity, further efforts towards monitoring programmes to obtain reliable and quality assured data on biodiversity at acceptable spatial and temporal resolutions are needed. Moreover, common methods to apply and harmonise data from different monitoring schemes should be developed.