Seeds of peasant subsistence: Agrarian structure, crop ecology, and Quechua agriculture in reference to the loss of biological diversity in the southern Peruvian Andes

Diverse native crop cultivars, which are both local and global resources, are presently disappearing due to social, economic, and cultural transformations of peasant communities in Third World countries. In the Paucartambo region of the southeastern Peruvian Andes agricultural households abandon native crops while remaining subsistence cultivators. The conversion of diverse-cultivar subsistence fields to mono-varietal parcels rather than the gradual replacement of individual taxa produces the local loss of cultivars.; Genetically mixed subsistence fields persist under specific systems of land use. Peasant households in Paucartambo determine land-use patterns as they organize their resources in response to the physical environment and several forms of social and economic relations, principally product and labor markets, local patrons, and agribusiness contracts. Community institutions and the inter-household coordination of livestock and agriculture further shape land use. The contradictory labor (time) and ecological (space) requirements of alternative agricultural configurations lead to the abandonment of diverse fields. Although cultivar loss is also linked to an uneven deterioration of the "diversity ethic" and knowledge of agriculturalists, distinctive regional patterns of land-use transformation, emerging out of overarching social structures and environmental constraints, underline the phenomenon.; Contrasting agroecological templates have molded distinctive patterns of cultivar loss of Paucartambo's two major crop complexes: maize (Zea mays) and potatoes (Solanum tuberosum subsp. andigenum, S. stenotonum, S. xchaucha, S. goniocalyx, S. phureja). Maize contains a relatively small number of widely distributed cultivars. Potatoes consist of a large number of cultivars; a majority possess endemic distributions. The wholesale abandonment of potato cultivars in particular micro-regions--including numerous sub-species of S. phureja in the lower Mapacho valley--is biologically more significant than the similarly complete disappearance of widely distributed maize cultivars. Although agriculturalists intercrop several cultivars (polyvariety) for specialized purposes of production and consumption, they also employ non-utilitarian "diversity" criteria of equal importance. Comprehensive explanations of resource distribution and use are necessary for establishing genetic conservation strategies and related development policies. Yet the ecological dynamics of agriculture are specific to particular societies. The study of cultivar loss and the management of in situ genetic resources demanded an integration of human geographical and biogeographical approaches.