摘要：We hypothesize that biological diversification across ecological, spatial, and temporal scales maintains andregenerates the ecosystem services that provide critical inputs—such as maintenance of soil quality, nitrogen fixation, pollination,and pest control—to agriculture. Agrobiodiversity is sustained by diversified farming practices and it also supplies multipleecosystem services to agriculture, thus reducing environmental externalities and the need for off-farm inputs. We reviewed theliterature that compares biologically diversified farming systems with conventional farming systems, and we examined 12ecosystem services: biodiversity; soil quality; nutrient management; water-holding capacity; control of weeds, diseases, andpests; pollination services; carbon sequestration; energy efficiency and reduction of warming potential; resistance and resilienceto climate change; and crop productivity. We found that compared with conventional farming systems, diversified farmingsystems support substantially greater biodiversity, soil quality, carbon sequestration, and water-holding capacity in surface soils,energy-use efficiency, and resistance and resilience to climate change. Relative to conventional monocultures, diversified farmingsystems also enhance control of weeds, diseases, and arthropod pests and they increase pollination services; however, availableevidence suggests that these practices may often be insufficient to control pests and diseases or provide sufficient pollination.Significantly less public funding has been applied to agroecological research and the improvement of diversified farming systemsthan to conventional systems. Despite this lack of support, diversified farming systems have only somewhat reduced mean cropproductivity relative to conventional farming systems, but they produce far fewer environmental and social harms. We recommendthat more research and crop breeding be conducted to improve diversified farming systems and reduce yield gaps when theyoccur. Because single diversified farming system practices, such as crop rotation, influence multiple ecosystem services, suchresearch should be holistic and integrated across many components of the farming system. Detailed agroecological researchespecially is needed to develop crop- and region-specific approaches to control of weeds, diseases, and pests
