Resilience and resistance of microbial communities against drought events, in a mature agroforestry system in Mediterranean area
Résumé
The intensification of agroecosystems has so far contributed to a global increase of food production at the expense of a number of ecosystem services. To achieve food security and face global changes, a shift to sustainable or ecological intensification of agroecosystems is needed. In this context, favoring biological interactions by increasing plant diversity within agroecosystems is of growing interest. Furthermore, complex pluri-specific systems could increase resilience or resistance against climate change. Amongst pluri-specific systems, agroforestry appears as a relevant candidate for enhancing managed biodiversity by associating perennial and annual species. These systems are also expected to enhance belowground diversity and functions which could contribute to explain their higher resilience to climate change compared to agroecosystems relying on single crop species. The aim of our study was thus to assess the impact of an agroforestry system on the resistance and resilience of soil microbial communities in relation with climate change and C cycle. Our hypothesis was that microbial resistance and resilience are greater in agroforestry system than in monocrop and decreases with the distance from the tree line. More specifically, we investigated soil microbial functions related to C, N and P cycles in the topsoil, by considering a spatial gradient from the tree line to the middle of the intercrop. Soils were sampled at the Restinclières experimental site, (South of France, nearby Montpellier). This site gathers 20 year-old walnut trees and wheat/barley/pea crop rotation (agroforestry system) and agricultural field (monocrop control). The soils were sampled at several distances perpendicular to the tree line. To test our hypothesis, we simulated drying-rewetting disturbance events on these monocrop vs. mature agroforestry system soils in lab conditions, and measured the microbial resistance and resilience index. Index calculation was based on soil microbial respiration.
Domaines
Biodiversité et EcologieOrigine | Fichiers éditeurs autorisés sur une archive ouverte |
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