Assessing bioenergy-driven agricultural land use change and biomass quantities in the U.S. Midwest with MODIS time series

Abstract

Bioenergy land use is expanding today as biofuel is consuming higher amount of agricultural production. In 2007, a widespread expansion of corn planting areas was recorded in the United States Department of Agriculture crop census. To better document the corn-related land use change, this study mapped the spatial distributions of four major annual crops (corn, soybean, winter wheat, and spring wheat) and three perennial crops (shortgrass, warm-season tallgrass, and cool-season tallgrass) in the Midwest. From 2006 to 2008, the 8-day, 500-m moderate resolution imaging spectroradiometer (MODIS) surface reflectance products were used to retrieve the normalized difference vegetation index (NDVI) composites. A support vector machine classifier was applied to identify these crops based on their unique growth cycles reflected from NDVI trajectories. The results showed a net increase of 15% of corn fields in 2007 accompanied by a net decrease of 16% in 2008. With the season-long integrated NDVI, this study also explored the geographic context and biomass proxy of native perennial grasses, an important feedstock of cellulosic biofuel. Mostly growing in North Dakota, South Dakota, Nebraska, and Kansas, their biomass quantities increased from west to east. This study indicates that frequent satellite observations may provide an efficient tool for monitoring biomass supplies and land use changes to assist national bioenergy decision-making.