It has been established that climate change affects the distribution of fauna and flora. These changes not only affect specific attributes of species such as diet or migratory strategy but also the interplay between species over large spatial scales, assuming that taxonomic groups with short generation time develop faster responses to pressures that are induced by climate change.
An extensive biodiversity monitoring approach has been carried out within the MACIS project in order to study birds and butterfly distributions at the European continental scale over the last two decades (i.e. 1990- 2008). Bird and butterfly communities in 9 490 and 2 130 sample sites respectively were characterized across Europe (from Spain to Finland) for each year from 1990 to 2008, using their community temperature index (CTI).
CTI expresses the relative composition of a local community of dwellers with regard to the high versus low temperature. This index was adopted in 2010 as a relevant indicator by the pan-European framework supporting the Convention on Biological Diversity (CBD) for gauging the rate of change in community towards temperature changes. CTI refers to a community of species regarding a single site, whereas STI (species temperature index) is linked to a given species and represents its average temperature range. CTI is obtained as the average of STI, weighted by species abundances.
The various results which have been obtained showed that both birds and butterflies do not keep up with temperature increase. They do not adjust their abundance according to the northward shift of their suitable climates throughout the continent. Birds have accumulated a climatic debt of 212 km and butterflies have likewise accumulated a climatic debt of 135 km. Here, climatic debt represents the delay in species response to changes in temperatures. These results indicate that birds and butterflies are not tracking climate change fast enough at large spatial scale. But butterflies developed a more rapid response than birds, probably because of their short life cycle and given they are ectothermic organisms, which means that they can track changes in temperature more closely.
The approach developed within this project is likely to be adapted to further studies in order to improve the traceability of climate change impacts on biodiversity, especially for mapping and characterizing the impact of climate change on different taxonomic groups.
Differences in the climatic debts of birds and butterflies at a continental scale.
Nature and climate change, VOL 2, 121-124, February 2012.