Mosaic indicators - theoretical approach for the development of indicators for species diversity in agricultural landscapes

Changed land use conditions, especially the intensification of agricultural production, have lead to a significant reduction in species diversity over the past several decades. In order to limit the impact of this reduction, indicators were developed and practical measures put forth which should serve to maintain biological diversity, but generally pay too little attention to different natural area conditions. In this light, an indicator concept for area species diversity on the basis of regional particularities has been developed which is based on a clear delineation of natural areas according to their unique landscape conditions. From the large number of species which appear in one area, a small number of key-species typical to the landscape, for which good ecological information is available, are selected as indicators. These species serve as the current status indicators for each area. With the goal of promoting regionally specific species diversity, the composition of indicators varies from area to area, according to each unique landscape. On the basis of an anticipated population change (target indicators) a comparison was made of habitat requirements and deficits in the existing habitats. In this manner, regionally targeted measures to improve habitats could be derived and implemented. So, the abundance of indicator species can be positively influenced and the regionally characteristic species diversity can thus be promoted. Such a set of indicators can serve as the basis for biodiversity management in completely agricultural landscapes and provide a picture of the total of all the single mosaic landscape units. (C) 2003 Elsevier Science B.V. All rights reserved.