Red alder trees distribution in the United States Pacific Northwest for 2002 summarized for NHDPlus v2 catchments
This spatial data set was created by the U.S. Geological Survey (USGS) to represent the basal area of red alder trees 
within each incremental watershed delineated in the NHDPlus v2 dataset in the Pacific Northwest region of the United 
States (Hydro Region 17; Major River Basin 7 (MRB7)) in 2001.