The distribution of groundwater habitats in Europe

Globalization and planetary environmental changes have stimulated the inventory of groundwater resources and biodiversity at continental and global scales but there has been no concurrent attempt to map the distribution of groundwater habitats even at continental scale. A vector version of the areal information contained in the international hydrogeological map of Europe (IHME) was produced, and thematic indicators for assessing its accuracy were established. Then, groundwater flow type, permeability and pore size were extracted from the vector IHME to define and map the distribution of 13 habitat types. The habitat map was used to test for latitudinal variations in habitat diversity (HD) and whether these variations might in part account for the latitudinal gradient of regional species richness. The HD of river catchments decreased significantly with increasing latitude after correcting for the effect of catchment area. HD decreased by half the amount of deviance attributed to latitude in a regression model of regional species richness, although the explanatory power of HD was probably limited by the coarse resolution of biogeographical regions. The groundwater habitat map of Europe represents a major step for the understanding, assessment and conservation of groundwater biodiversity and for incorporating ecological perspectives in groundwater management policy.