Model-based analysis of the agglomeration bonus for the conservation of twelve meadow bird species in an agricultural landscape

The agglomeration bonus has been proposed as an effective and cost-effective instrument for inducing the spatial aggregation of conservation measures. It consists of a spatially homogenous base payment (like most existing payment schemes) plus a bonus for each adjacent land parcel that is conserved, too. While the agglomeration bonus has been investigated in numerous theoretical studies, very few applied studies exist to date. We extend a recent modelling study which analysed the effect of several grassland conservation schemes on meadow bird species in the Federal State of Saxony in Germany, by adding to the homogenous payment the described bonus. As expected, the bonus induces a spatial aggregation of the conservation measures. However, for typical bird dispersal ranges this does not reflect in an increased scheme cost-effectiveness. Only for much smaller dispersal ranges, which would be typical for insect species, the cost-effectiveness of the scheme would increase. We conclude that in complex agricultural landscapes with many land-use measures and species the agglomeration bonus may have limited value. Instead it should be used as a targeted instrument for the conservation of selected species of high conservation value that depend on very particular types of land use and have a small dispersal range.