USGS GAP provides web service connections for its data sets, as follows:
Land Cover
- National Vegetation Classification-Land Use — dominant general growth forms adapted to basic moisture, temperature, and/or substrate or aquatic
- National Vegetation Classification-Subclass Land Use — global macroclimatic factors driven primarily by latitude and continental position, or reflect overriding substrate or aquatic conditions
- National Vegetation Classification-Formation Land Use — global macroclimatic conditions as modified by altitude, seasonality of precipitation, substrates, hydrological conditions
- National Vegetation Classification-Division Land Use — continental differences in mesoclimate, geology, substrates, hydrology, disturbance regimes
- National Vegetation Classification-Macro Group Land Use — sub-continental to regional differences in mesoclimate, geology, substrates, hydrology, disturbance regimes
- National Vegetation Classification-Ecological Systems Land Use — co-occuring plant communities influenced by similar ecological processes
