Know your limits - The need for better data on species responses to soil variables

Species distribution modelling has largely focused on larger spatial scales and the significance of climatic variables for future species ranges. In this study, we argue that more attention should be paid to local processes and the responses of species along soil gradients, as habitat destruction and change in terms of an altered edaphic environment are the main factors behind the decline of many plant species in Central Europe. Examples from deciduous forests and calcareous dry grasslands show that response optima and especially response limits relative to soil pH and phosphorus availability are more closely related to the range sizes and threat levels of species than the traditionally applied Ellenberg indicator values, and that species assumed to have similar preferences show considerable, ecologically relevant differences in their thresholds. There is an urgent need for collecting more and better soil data and for analyzing the relationships between the spatial distribution of plant species and edaphic variables on regional and local scales, in order to identify optimal and marginal habitats of species as a pre-requisite for their successful conservation.