Attributes for NHDPlus Catchments (Version 1.1) for the Conterminous United States: NLCD 2001 Tree Canopy
This data set represents the mean percentage of tree canopy from the Canopy Layer of the 
National Land Cover Dataset 2001,  (LaMotte and Wieczorek, 2010), compiled for every 
catchment of NHDPlus for the conterminous United States. The source data set represents 
tree canopy percentage for the conterminous United …