Connectivity of the American agricultural landscape: Assessing the national risk of crop pest and disease spread

摘要

More than two-thirds of cropland in the United States is devoted to the production of just four crop species—maize, wheat, soybeans, and cotton—raising concerns that homogenization of the American agricultural landscape could facilitate widespread disease and pest outbreaks, compromisingthe national food supply. As a new component in national agricultural risk assessment, we employed a graph-theoretic approach to examine theconnectivity of these crops across the United States. We used county crop acreage to evaluate the landscape resistance to transmission—the degree towhich host availability limits spread in any given region—for pests or pathogens dependent on each crop. For organisms that can disperse underconditions of lower host availability, maize and soybean are highly connected at a national scale, compared with the more discrete regions of wheatand cotton production. Determining the scales at which connectivity becomes disrupted for organisms with different dispersal abilities may helptarget rapid-response regions and the development of strategic policies to enhance agricultural landscape heterogeneity.