Reverse Updating National Land Cover Data (NLCD) 2001 Canopy Layer
—Creating 1990 Percent Canopy Layer for the Northeastern US Metropolitan Areas

The USDA Forest Service Northeastern Area is studying the percent canopy cover of Northeastern US metropolitan areas. To support this work, MDA Federal performed a change detection and reverse update process utilizing NLCD 2001 products and circa 1990 Landsat imagery to derive a percent canopy layer for the year 1990. This layer was created for 163 Metropolitan Areas using MDA Federal’s Cross Correlation Analysis (CCA) change detection algorithm to identify changes between 2001 era and 1990 era Landsat images. The percent canopy in changed areas was computed for circa 1990 based on NLCD 2001 Percent Canopy layer produced by USGS to support the Multi-Resolution Land Characteristics (MRLC) Consortium.

The NLCD 2001 Percent Canopy Layer, masked with change areas, served as a dependent (training) data layer for Classification and Regression Tree Classifier (CART) to estimate canopy percentage for the year 1990. These estimates were incorporated into NLCD 2001 Canopy Layer within changed areas to generate a 1990 percent canopy layer.