Spatial agreement between two land-cover data sets stratified by agricultural eco-regions

Two of the most widely used land-cover data sets for the United States are the National Land-Cover Data (NLCD) at 30-m resolution and the Global Land-Cover Characteristics (GLCC) at 1-km nominal resolution. Both data sets were produced around 1992 and expected to provide similar land-cover information. This study investigated the spatial distribution of NLCD within major GLCC classes at 1-km unit over a total of 11 agricultural-related eco-regions across the continental United States. Our results exhibited that data agreement or relationship between the GLCC and NLCD was higher for the eco-regions located in the corn belt plains with homogeneous or less complicated land-cover distributions. The GLCC cropland primarily corresponded to NLCD row crops, pasture/hay and small grains, and was occasionally related to NLCD forest, grassland and shrubland in the remaining eco-regions due to high land-cover diversity. The unique GLCC classes of woody savanna and savanna were mainly related to the NLCD orchard and grassland, respectively, in the eco-region located in the Central Valley of California. The GLCC urban/built-up among vegetated areas strongly agreed to the NLCD urban for the eco- regions in the corn belt plains. A set of subclass land-cover information provided through this study is valuable to understand the degrees of spatial similarity for the major global vegetated classes. The subclass information from this study provides reference for substituting less-detailed global data sets for detailed NLCD to support national environment studies.