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RESEARCH PRODUCT

Functionnal aspects of biodiversity in relation to plant health

subject

description

 Texte intégral; The most visible impact of human activities on biodiversity concerns species which are part of our cultural heritage but a huge part of the diversity is still hidden, mainly in the ocean, in extreme environments and of course in the soil. Although some estimations can be proposed, they are all considered as under-evaluations of the putative number of taxa that could be present on (in?) the planet Earth. Despite it is not yet known, this biodiversity contributes to different services through the functioning of ecosystems, and thus influences the sustainability of these ecosystems. This was the case for instance when the unsuspected major roles of the archeabacteria in the biogeochemical cycles was recently revealed. At a smaller scale, the one we can approach in the frame of this workshop, it is clear that biodiversity is modelled by farmed ecosystems but in return, it contributes directly to the farmed ecosystems, via the regulation of parasites and diseases of crops, by contributing to the fertility of the soils and to soil health. It seems therefore essential to understand the nature of the interactions between biodiversity and agriculture to both preserve the former and improve the latter but so far, none of the various indices used to measure the diversity can be used as an indicator of the soil Health. This will lead us to consider the definition of the biodiversity and the functional significance of the taxonomic descriptions of the biota in and on the soil and to admit that the gap in between diversity and soil functioning is still difficult to fill in, functional redundancies being mainly responsible for this, whatever the domains. Using some examples among the biota including bacteria, fungi, nematodes, earthworms and other "soil engineers" in agricultural soils in which diverse plant genotypes are grown, we will try to show that the result of the millennia of selection should provide a potential for the adaptation of farming systems allowing to control the bio-aggressors of the plants without eroding the biodiversity of these interacting components.