Driving forces from soil invertebrates to ecosystem functioning: the allometric perspective.

The European soil policy is being focussed towards a more conscious and sustainable use of the soil, taking into account ecological, economical and societal dimensions. Living soil organisms are reliable bioindicators, as they provide the best reflection of the soil system, ecological services and ecosystem functioning therein. These most complex (bio)physical systems indicate, among others, the energy flow. Such processes can be described by rather simple power law relationships. In fact, the average body mass (dry weight) can be seen as an inherent species property, while population density is a much more flexible parameter reflecting ecosystem state. In this study, I review the interactions between these items in relation to feedbacks and conjectured relationships which can be seen as ecological networks. From this novel perspective, allometry can be used as an integrated measure for the anthropogenic influence on landscapes and related food webs. Allometry is, therefore, a perfect surrogate for land use intensity in modelling of field effects for restoration ecology and conservation biology. Robust correlations will be addressed between the density dependence of invertebrates and the ability of soil systems themselves to recover after disturbance. Quantitative indicators of soil community composition and related ecological services are proposed and their application for ecological risk assessment is illustrated.