Relevance of different soil fauna and microflora groups in the monitoring of soil biodiversity: RMQS-Biodiv, a french Pilote area experience
Résumé
Soil biota play essential roles in delivering key ecosystem goods and services, and are both directly and indirectly responsible for acting in many important functions (nutrient release, soil structure maintain, contribution to water storage). It is thus essential to characterize both the species diversity and the biological functions. In order to monitor soil biodiversity (species and function) in relation to land use (mainly agricultural practices) and pedoclimatic parameters, a French program « RMQS-biodiv » was developed at a wide regional scale (Brittany). An important national research collaboration (12 research teams) supported the program, that undertook the study of several biological parameters such as macrofauna diversity (earthworms, total macro-invertebrates), mesofauna diversity (acarina and collembola), microorganisms (nematodes diversity, microbial biomass, bacterial and fungal diversity), as well as functional biological parameters (soil respiration, humus index, macrofauna and mesofauna activity: biogenic structure, feeding activity). This program was connected to a larger soil monitoring network developed at national scale (Soil Quality Measurement Network- RMQS) which monitored soil parameters (chemistry, physic) and agricultural management using a regular grid (16 X 16 km) covering the whole national territory. The link between these two programs allowed the study of biological parameters in the light of soil and agricultural characteristics, and thus the definition of biological indicators. The results obtained from the analysis of 115 sites sampled in 2006 and 2007, will be discussed in terms of relevance of these biological criteria as indicators, and in fine of their transfer to field actors (technicians) who are in charge of new tool implementation on agronomical management assistance. Furthermore, the results will also be discussed with respect to propositions and recommendations made by the ENVASSO project (Environmental Assessment of Soil for Monitoring), especially the biological criteria proposed by the European project and the hierarchy of these criteria.