Abstract
In European agricultural landscapes, conventional farming and climate changes can amplify soil erosion susceptibility. Recent policies have encouraged agroforestry practices that are believed to provide a number of ecosystem services and improve biodiversity. However, fundamental and applied research is still required to determine how best to plant and manage, depending on land use, climate and topography. Within this context, our project investigates the ecosystem services provided by crop/forest systems, in relation to soil structural stability. We chose to study the following variables: stability of soil aggregates, root traits and distribution, microbial activity and microbial metabolic diversity. The project involves eight field sites representative of different agro-forests which have distinct ages and pedoclimatic characteristics. On each site, a systematic sampling was performed to assess the influence of the tree row, the distance to the trees and the perennial plant cover on the variables listed above. The relationship between soil aggregates and functional traits of plants and soil microbes is studied with substantial field measurements involving a large network in French agroforests. The preliminary results of this project suggest that the tree row and the proximity of trees are beneficial for soil aggregate stability. This result is related to the quantity of roots. The magnitude of these effects seems however to depend on the characteristics of the agroforestry system. The results of this research should allow stakeholders and agroforesters to better determine adapted spatial management strategies with regard to plant root traits and erosion risks.