Approaches to a quantification of the decrease of dragonfly species in industrialized countries

A quantification of the decrease of dragonfly spp. will be achieved by preparing distribution maps which, by using different symbols, should allow an identification of spatial and temporal distribution of records. Recent records should be further classified and commented with regard to their actual status. Stable populations should be especially denoted in the maps. Criteria for estimating the status of a dragonfly population are given, using Gomphus vulgatissimus in Schleswig-Holstein, northern German Federal Republic, as an example.