A FRAMEWORK FOR REGIONAL AGROECOSYSTEMS CHARACTERIZATION USING THE NATIONAL RESOURCES INVENTORY

An agroecological framework is used to examine the relations among nat ural resources and agriculture. Spatial representation of selected agr oecosystems characteristics was accomplished using the National Resour ces Inventory (NRI). Natural resource and anthropogenic variables from the NRI were spatially aggregated to produce maps showing the regiona l variability in area-weighted values of agroecosystem components. Map s of natural vegetation, agricultural land use, crop diversity, artifi cial drainage, irrigation, net soil loss, and conservation practices s how the extent to which resources have been modified to support agricu lture in the Midwest. The frequency of land used for crops and pasture exceeds 70% in much of the region. Natural vegetation occupies less t han 10% of the land in many areas. Subsurface and surface drainage, mo re than 35% of some areas, has contributed to loss of wetlands having a direct effect on water quality. Irrigation has diverted water from n atural ecosystems and increased the potential for leaching of agrichem icals. Excess erosion may threaten long-term productivity in parts of the region even though conservation practices have been implemented. E xamination of these and other elements in an agroecosystem framework m ay be useful in the search for systems to sustain agriculture and natu ral resources in the region. Such a framework can also be used to loca te areas where mitigation of degraded resources is most needed; identi fy areas where research into causes of degradation can yield the most information; and where policies to improve off-site damage may be most effectively implemented.