Soil fauna community and ecosystem's resilience: A food web approach

There is an increasing concern for the conservation of soil biodiversity and its ecosystem functions. In this context, it is crucial to comprehend the typical response times of the community (meso and macrofauna) to disturbances associated with different land uses. If we consider a disturbance as some degree of disorganization produced by an input of energy into the system, we realise that the issue is how the surplus of energy is dissipated, and with at what efficiency. Emerging properties of a community (diversity, resilience, stability) are affected by a cascade of processes that act at different spatial and temporal scales. To diagnose disturbance effects, it is necessary to use new tools of observation. One of these tools is the analysis of food webs that clearly shows the relationships among species and energy fluxes. We present here an example of the use of the food web approach to study the effects of foresting a naturalized pasture of the humid Argentinean Pampa with exotic species of trees (Eucalyptus camadulensis and Populus nigra). We show that the basic architecture of food webs remains similar under different treatments (related to the input of new detritus source) in a short time (60 days). However, the proposed approach in this study enables to design a simple decision scheme to formulate hypotheses about possible effects of stronger disturbances.