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Multifonctionnalité des systèmes viticoles conduits en agriculture biologique : une analyse intégrant les performances écologiques, agronomiques et économiques

Abstract : The main challenge for viticulture is to develop production systems that limit environmental impacts while maintaining acceptable income for winegrowers. Optimizing ecological functions supported by biodiversity in agro-ecosystems seems to be a promising way for the development of multifunctional wine-growing systems. Current knowledge indicates that organic agriculture at the local and landscape scale can promote biodiversity and the services it provides in wine-growing landscapes. However, knowledge is currently very limited, particularly about which characteristics of communities can promote ecological functions. Moreover, how organic farming practices affect agronomical, ecological and economic performances in wine-growing landscapes beyond the simple effects on biodiversity remains largely unknown. In this work, we used an experimental design consisting in 20 pairs of fields allowing us to disentangle the effects of semi-natural habitats from the amount of organic farming in the landscape. We evaluated the multifunctionality of farming systems through the characterization of communities at different trophic levels, the measurement of several ecosystem functions as well as an evaluation of yields, production costs, agricultural practices and the use of pesticides. We first found that considering the form of the distribution of a key functional trait, predator’s biomass, within predator communities allows us to better understand trophic interactions in food webs and shade light o the relationships between biodiversity and biological pest control. Our results indicate that predator communities largely dominated by low-biomass species provide higher level of pest control. In addition, our work showed that the beneficial effects of organic farming practices on biodiversity do not apply to all trophic levels. Organic farming promotes the abundance of predator communities but decreases the abundance of wild pollinators and soil communities, due to more intensive cultural practices such as tillage. Our work also showed that the average multifunctionality of farming systems does not differ between fields conducted under organic and conventional agriculture, but that these average performances result from very contrasted profiles of individual performances. In addition to the overall beneficial effects of organic farming on biodiversity conservation, organic farming leads to lower yields, higher levels of pest infestations, lower pesticide use but lower production costs compared to systems carried out in conventional agriculture. The results of our study provide (1) novel knowledge about the importance of functional diversity in the relationships between biodiversity and agroecosystem functioning , (2) contextualized references on the multiple performances of wine-growing systems to guide the ecological intensification of wine-growing landscapes, as well as (3) innovative scientific knowledge about the consequence of organic farming expansion on the multifunctionality of farming systems.
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Submitted on : Saturday, June 5, 2021 - 3:08:09 PM
Last modification on : Sunday, June 6, 2021 - 3:27:24 AM
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Noémie Ostandie. Multifonctionnalité des systèmes viticoles conduits en agriculture biologique : une analyse intégrant les performances écologiques, agronomiques et économiques. Biodiversité et Ecologie. Université de Bordeaux, 2021. Français. ⟨NNT : 2021BORD0068⟩. ⟨tel-03250966⟩

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