07/11/2011
Impact of Bioenergy Feedstocks on Agricultural Landscapes
The Science
Simplification of the agricultural landscape due to expansive monocultures of individual crops reduces habitat diversity and has long been believed to increase insect pest pressure with a resulting need for more insecticides. This assumption seems logical, but has lacked supporting scientific evidence, evidence needed to establish a science-based land-use policy that includes dedicated bioenergy crops. Now, researchers at the DOE Great Lakes Bioenergy Research Center (GLBRC) have reported an analysis of cropping systems across 562 counties in seven Midwestern states. They found a significant correlation between insecticide use and land simplification (i.e., less natural habitat). The results suggest that plantings of more minimally managed perennial bioenergy crops requiring less insecticide use may mitigate some of the negative effects associated with continued simplification. This study provides a scientific basis for understanding the impact that the greater demand for bioenergy feedstocks will have on the agricultural landscape.
The Impact
The research team estimated that, across the seven-state region in 2007, landscape simplification was associated with insecticide application to 1.4 million hectares and an increase in direct costs totaling between $34 and $103 million. Both the direct and indirect environmental costs of landscape simplification should be considered in design of land use policy that balances multiple ecosystem goods and services.
Summary
Agronomic intensification has transformed many agricultural landscapes into expansive monocultures with little natural habitat. A pervasive concern is that such landscape simplification results in an increase in insect pest pressure, and thus an increased need for insecticides. Researchers tested this hypothesis across a range of cropping systems in the Midwestern United States, using remotely sensed land cover data, data from a national census of farm management practices, and data from a regional crop pest monitoring network. Researchers found that, independent of several other factors, the proportion of harvested cropland treated with insecticides increased with the proportion and patch size of cropland and decreased with the proportion of seminatural habitat in a county. They also found a positive relationship between the proportion of harvested cropland treated with insecticides and crop pest abundance, and a positive relationship between crop pest abundance and the proportion cropland in a county. These results provide broad correlative support for the hypothesized link between landscape simplification, pest pressure, and insecticide use.
BER Program Manager
Kari Perez
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Biological Systems Science Division
[email protected]
References
Meehan, T. D., B. P. Werling, D. A. Landis, and C. Gratton. 2011. “Agricultural Landscape Simplification and Insecticide Use in the Midwestern United States,” Proceedings of the National Academy of Sciences of the United States of America 108, 11500–505. DOI:10.1073/pnas.1100751108.