Browsing by Author "Kremen, Claire"

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Diversified Farming Systems: An Agroecological, Systems-based Alternative to Modern Industrial Agriculture
(2012) Kremen, Claire; Iles, Alastair; Bacon, Christopher M.
"This Special Issue on Diversified Farming Systems is motivated by a desire to understand how agriculture designed according to whole systems, agroecological principles can contribute to creating a more sustainable, socially just, and secure global food system. We first define Diversified Farming Systems (DFS) as farming practices and landscapes that intentionally include functional biodiversity at multiple spatial and/or temporal scales in order to maintain ecosystem services that provide critical inputs to agriculture, such as soil fertility, pest and disease control, water use efficiency, and pollination. We explore to what extent DFS overlap or are differentiated from existing concepts such as sustainable, multifunctional, organic or ecoagriculture. DFS are components of social-ecological systems that depend on certain combinations of traditional and contemporary knowledge, cultures, practices, and governance structures. Further, as ecosystem services are generated and regenerated within a DFS, the resulting social benefits in turn support the maintenance of the DFS, enhancing its ability to provision these services sustainably. We explore how social institutions, particularly alternative agri-food networks and agrarian movements, may serve to promote DFS approaches, but note that such networks and movements have other primary goals and are not always explicitly connected to the environmental and agroecological concerns embodied within the DFS concept. We examine global trends in agriculture to investigate to what extent industrialized forms of agriculture are replacing former DFS, assess the current and potential contributions of DFS to food security, food sovereignty and the global food supply, and determine where and under what circumstances DFS are expanding rather than contracting."
Ecosystem Services in Biologically Diversified versus Conventional Farming Systems: Benefits, Externalities, and Trade-Offs
(2012) Kremen, Claire; Miles, Albie
"We hypothesize that biological diversification across ecological, spatial, and temporal scales maintains and regenerates 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 multiple ecosystem services to agriculture, thus reducing environmental externalities and the need for off-farm inputs. We reviewed the literature that compares biologically diversified farming systems with conventional farming systems, and we examined 12 ecosystem services: biodiversity; soil quality; nutrient management; water-holding capacity; control of weeds, diseases, and pests; pollination services; carbon sequestration; energy efficiency and reduction of warming potential; resistance and resilience to climate change; and crop productivity. We found that compared with conventional farming systems, diversified farming systems 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 farming systems also enhance control of weeds, diseases, and arthropod pests and they increase pollination services; however, available evidence 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 systems than to conventional systems. Despite this lack of support, diversified farming systems have only somewhat reduced mean crop productivity relative to conventional farming systems, but they produce far fewer environmental and social harms. We recommend that more research and crop breeding be conducted to improve diversified farming systems and reduce yield gaps when they occur. Because single diversified farming system practices, such as crop rotation, influence multiple ecosystem services, such research should be holistic and integrated across many components of the farming system. Detailed agroecological research especially is needed to develop crop- and region-specific approaches to control of weeds, diseases, and pests."
Monitoring Impacts of Natural Resource Extraction on Lemurs of the Masoala Peninsula, Madagascar
(1998) Merenlender, Adina; Kremen, Claire; Rakotondratsima, Marius; Weiss, Andrew
"Monitoring the influence of human actions on flagship species is an important part of conserving biodiversity, because the information gained is crucial for the development and adaptation of conservation management plans. On the Masoala Peninsula in Madagascar, we are monitoring the two largest prosimian species, Eulemur fulvus albifrons and Varecia variegata rubra, at disturbed and undisturbed forest sites to determine if extraction of forest resources has a significant impact on the population viability of these species. To test the sensitivity of lemur species to routine extraction of natural resources by local villagers, we compared population demography and density for both species across six study sites, using a new census technique. Three of the study sites were closer to villages and, therefore, were more impacted by resource extraction than the others. Our data on more than 600 individual primates suggest that the level of resource extraction did not significantly influence group size, fecundity, or density for either species over the two-year period of this study; however sex ratios in Eulemur were biased toward juvenile and adult females in more disturbed areas, suggesting that males may be emigrating from areas of less suitable habitat. Population densities at each site and estimates of population size across the entire peninsula were calculated and used to evaluate the design of a new park in the area, and to ensure that it will be large enough to support viable populations of these threatened primates. These estimates were calculated by obtaining the surface area of each study region from a geographic information system. Monitoring of these species continues in buffer zone areas of the park, where resource extraction is still permitted."