Abstract
Agricultural management is a major factor driving the change of faunal
richness in anthropogenic landscapes. Thus, there is an urgent need to
develop tools that allow decision-makers to understand better intended
and unintended effects of agricultural policy measures on biodiversity.
Here we demonstrate the potential of such a tool by combining a
socio-economic model with the biodiversity model GEPARD to forecast the
response of bird and carabid species richness to two scenarios of
agricultural subsidies: (1) subsidies based on production levels and
prices and (2) direct income support that is independent of production
levels. We focussed on farmland of the Lahn-Dill area, Germany, as an
example of European regions with low intensity farming. GEPARD predicts
faunal richness and is based on multi-scaled resource-selection
functions. Under both scenarios the area of predicted losses in species
richness of birds and carabids was larger than the area of predicted
gains in species richness. However, the area with predicted losses of
avian richness was smaller under the direct income support scenario
than under the production-based subsidy scenario, whereas the area with
predicted losses of carabid species richness was smaller under the
production-based subsidy scenario than under the direct income support.
Yet locally, richness gains of up to four species were predicted for
carabids under both scenarios. We conclude that the sometimes
contrasting and heterogeneous responses of birds and carabids at
different localities suggest the need for spatially targeted subsidy
schemes. With the help of the GIS-based approach presented in this
study, prediction maps on potential changes in local and regional
species richness can be easily generated.
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