This dataset represents the average height of the dominant vegetation for a 30-m grid cell within individual local and accumulated upstream catchments for NHDPlusV2 Waterbodies based on field reference data and Landsat, elevation, and ancillary data.
Catchment boundaries in LakeCat are defined in one of two ways, on-network or off-network. The on-network catchment boundaries follow the catchments provided in the NHDPlusV2 and the metrics for these lakes mirror metrics from StreamCat, but will substitute the COMID of the NHDWaterbody for that of the NHDFlowline. The off-network catchment framework uses the NHDPlusV2 flow direction rasters to define non-overlapping lake-catchment boundaries and then links them through an off-network flow table.
The Existing Vegetation Type (EVT) layer represents the species composition currently present at a given site. Vegetation map units are primarily derived from NatureServe's Ecological Systems classification, which is a nationally consistent set of mid-scale ecological units. Additional units are derived from NLCD, National Vegetation Classification Standard (NVCS) Alliances, and LANDFIRE specific types. - Reclassified into introduced managed vegetation cover - IntrodManagVeg class - reclass from EVT - groups (EVT_GP) = (701,702,703,704,705,706,707,708,709,711,731)
Canopy height is generated separately for tree, shrub and herbaceous lifeforms using training data and other layers. EVH is determined by the average height weighted by species cover and based on the existing vegetation type (EVT) lifeform. Decision tree models using field reference data and Landsat, elevation, and ancillary data are developed separately for each lifeform. Decision tree relationships are used to generate lifeform specific height class layers, which are merged into a single composite EVH layer.
The vegetation characteristics (%) were summarized to produce local catchment-level and watershed-level metrics as a continuous data type.