Ecological validation of soil food-web robustness for managed grasslands

The actual relationship between biodiversity and ecosystem functioning is a challenging and intriguing issue which always fascinated many ecologists. In this study the detrital soil food webs of three temperate sandy ecosystems have been compared in the attempt to quantify the extent to which anthropogenic action affects them. The structure of the corresponding food webs was analysed and their topological robustness was calculated through the use of a dynamic model, which is briefly introduced. Our Alteration Index has been used here for the first time to enable a direct comparison between different food-web architectures. The results show that all soil networks have a disassortative nature, as expected for theoretical food webs. The values of the clustering coefficient, of the connectance and of the complexity, together with the calculation of the robustness suggest that the fallowed pasture with low pressure management is more robust than the other two grasslands under middle intensity management. The robustness shown by ecological networks could be useful elsewhere for evaluating the sustainability of agricultural practices to which the soil system is subject.