One of the primary objectives in landscape approaches to management is the protection of multiple ecosystem services. Last week researchers from the World Agroforestry Centre provided lessons on how adopting a landscape scale can improve incentives to manage land for a spectrum of ecosystem services. But a better understanding of how agricultural systems themselves provide these services, and to what extent, is still desperately needed. Today, Claire Kremen and Albie Miles (University of California, Berkeley) begin to tackle this question, discussing the findings of a new study on ecosystem services in biologically diversified farming systems, and the benefits, tradeoffs, and externalities in comparison with conventional agricultural systems.
While achieving impressive levels of crop productivity over the past six decades, modern agricultural systems have accomplished this feat at significant ecological and social costs. With the industrialization of agriculture, biologically diversified farming systems have gradually been replaced with biologically simplified monocultures highly dependent on fossil energy and industrial inputs. The industrialization of agriculture and the loss of biodiversity in and around agroecosystems has led to a significant reduction in the provisioning of globally important ecosystem services to and from agriculture, including crop pollination, natural pest control, soil and water quality maintenance, efficient nutrient cycling, carbon sequestration, and biodiversity conservation. Further, the suite of practices and agrochemical inputs that substitute for ecosystem services in much of modern agriculture contribute to significant environmental, social, and economic impacts: soil and water quality degradation, eutrophication of surface and groundwater, loss of wild biodiversity, increased greenhouse gas emissions, marine hypoxic zones and occupational and dietary exposure to agricultural chemicals.
Biologically diversified farming systems are agricultural systems that integrate a cluster of farming practices and/or landscape management strategies. These strategies intentionally incorporate the various ecological functions plants, animals, and microbes perform (e.g. decomposition or water filtration) at multiple spatial or temporal scales to enhance the ecosystem services critical for agriculture. In a new major study published in the journal Ecology and Society, we note that a large body of scientific research supports the claim that these types of systems outperform conventional monocultures across a wide range of globally important ecological and social services.
Compared to chemically managed monocultures, biologically diversified farming systems support substantially greater biodiversity, improve soil quality and water-holding capacity, sequester carbon, use energy more efficiently, and increase the resistance and resilience to climate change. When contrasted with conventional agriculture, biologically diversified farming systems also tend to enhance the biological control of weeds, diseases, and arthropod pests, while increasing pollination services from native insects. Importantly, the available evidence indicates that farming system diversification alone may not provide these latter ecosystem services at levels sufficient for optimum production and economic needs. However, the above findings illustrate the potential of biologically diversified farming systems to reduce or ameliorate many pressing global environmental impacts caused by agriculture while still enhancing key ecosystem services and producing similar yields. With a significant increase in support for agroecological research and development, the full potential of biologically diversified farming systems may be realized.
Kremen, C. and A. Miles. 2012. Ecosystem services in biologically diversified versus conventional farming systems: benefits, externalities, and trade-offs. Ecology and Society 17(4): 40. http://dx.doi. org/10.5751/ES-05035-170440. Synthesis, part of a Special Feature on A Social-Ecological Analysis of Diversified Farming Systems: Benefits, Costs, Obstacles, and Enabling Policy Frameworks.