Live tree species basal area of the contiguous United States (2000-2009)

This data publication contains raster maps of live tree basal area for each tree species along with corresponding assessment data. An efficient approach for mapping multiple individual tree species over large spatial domains was used to develop these raster datasets. The method integrates vegetation phenology derived from MODIS imagery and raster data describing relevant environmental parameters with extensive field plot data of tree species basal area to create maps of tree species abundance and distribution at a 250-meter (m) pixel size for the contiguous United States. The approach uses the modeling techniques of k-nearest neighbors and canonical correspondence analysis, where model predictions are calculated using a weighting of nearest neighbors based on proximity in a feature space derived from the model. The approach also utilizes a stratification derived from the 2001 National Land-Cover Database tree canopy cover layer.
The mapping methodology and resultant datasets were intended to address three major issues. 1) Land use policy decisions are often made at the landscape scale because landscape processes, like risk of forest pests or fire, occur over large areas. 2) Distribution and abundance information is often needed for individual species as opposed to forest types because individual species can play significant roles in natural systems, may have high economic impact, or may be indicators for ecosystem health. 3) The maintenance of a realistic species covariance structure across a set of maps of individual species is important because species assemblage information is used in coarse scale modeling of ecosystem processes like response to disturbance, urbanization, and climate change.
Original metadata date was 09/09/2013. Minor metadata updates on 12/15/2016.