Habitat models and their transfer for single and multi species groups: a case study of carabids in an alluvial forest

Environmental factors influencing the occurrence of single species and mult i species groups of carabids in alluvial forest at the River Elbe were dete rmined with habitat suitability models. Two representative species for diff erent ecotypes present in the investigated community, Agonum livens and Pte rostichus oblongopunctatus, were defined by means of a discriminant analysi s. The two species differed greatly in their microhabitat distribution. Ago num livens was chosen as target species for a multi species group of wetlan d species that inhabited the fringes of temporary waters in the forest. In contrast, P. oblongopunctatus should represent species of deciduous forests . Using stepwise multiple logistic regression statistically significant hab itat suitability models were estimated, reliably predicting the species' oc currence. A subsequent evaluation by cross-validations and receiver operati ng characteristic (ROC) curves indicated a high discriminatory power. A tra nsfer of the model onto different data sets in time was applied to validate the model. Alternatively, a multi species habitat model, taking into accou nt weighted occurrence data of the wetland species group, was estimated. In order to show that the chosen target species truly holds an umbrella effec t upon the represented multi species group, we used ROC curves to indicate the transferability of the target species' habitat model for the multi spec ies group and vice versa.