The stability of crop production: trade-offs in pollination-dependent agriculture
Résumé
Historically, demand for increased crop production has been satisfied by agricultural practices that include land conversion into agricultural land and improvements in crop yield. The benefits of persisting in this approach are challenged by the existence of apparent yield plateaus for many major crops and of crop yield saturating responses to increasing levels of pesticides. Notably, despite the importance of yield stability and the empirical evidence that magnitude and stability of ecosystem functions do not necessarily co-vary positively, few studies on the stability of crop yield have been attempted. Here, we develop a model for crop yield dynamics in a spatially heterogeneous agricultural landscape to explore possible trade-offs between crop production (yield mean and stability) and biodiversity conservation (pollinators) in agroecosystems. We focus on how landscape composition (proportion of semi-natural habitat within the agricultural landscape) and crop pollination dependence shape these trade-offs and how they influence the mean and stability of pollinators, and that of crop yield. We find that agricultural practices impose trade-offs in pollination-dependent agriculture between provisioning and regulating/cultural services in agroecosystems, such as between crop area and semi-natural habitat for pollinator communities, which not only affect the production of crops, but also their stability. These trade-offs are conditioned by mechanisms associated with the pollinator dependence of crops, and the crop relative responsiveness. Agriculture has become more pollinator-dependent over time, and, in order to develop more efficient and sustainable management policies, it is essential to understand the mechanisms driving these trade-offs.