Major World Ecosystem Complexes Ranked By Carbon In Live Vegetation: A Database, CDIAC NDP-017

This package contains a computerized database used to generate a global vegetation map of 44 different land ecosystem complexes comprising seven broad groups. The database and accompanying map provides a basis for making improved estimates of vegetation areas and carbon quantities, of natural biological exchanges of CO2, and, eventually, of the net historic shifts of carbon between the biosphere and the atmosphere. The map is derived from patterns of preagricultural vegetation, modern areal surveys, and intensive biomass data from research sites. The cells of each type in each 0.5 degree latitude band and adding their areas over latitude bands gave total area estimates for these ecosystem complexes. Some independent area estimates are brought together in Olson et al. (1983) and confirm the thesis that some earlier estimates of forest area and forest contribution to global carbon inventories were apparently overestimated. Current estimates of the range in density of carbon- per-unit area are discussed in Olson et al. (1983). Multiplying the low, medium, and high-density estimates by ecosystem area gives corresponding estimates of the global total carbon by ecosystem complexes. Estimating the inventory of carbon in major world ecosystems and the exchanges with the atmosphere and other major reservoirs has been approached in two ways. In the first approach, developing broad global patterns uses potential vegetation maps, or associates vegetation types with climatic or other environmental factors independent of local disturbance. In the second approach, developing modern regional or stand-type estimates is based on analyses of current vegetation and land-use practices. This method uses updated resource maps of natural vegetation, forestry surveys, agricultural yields and human, economic, and geopolitical considerations. Both approaches were applied in the development of the ecosystem map. In 1980, this data base and the corresponding map were completed after more than 20 years of field investigations, consultations, and analyses of published literature. They characterize the use and vegetative cover of the Earth's land surface with a 0.50 x 0.50 degree grid. This world-ecosystem-complex data set and the accompanying map provide a current reference base for interpreting the role of vegetation in the global cycling of CO2 and other gases and a basis for improved estimates of vegetation and soil carbon, of natural exchanges of CO2, and of net historic shifts of carbon between the biosphere and the atmosphere. The data are presented in two alternative files: one matrix file of 122 kB, providing latitude, longitude, and ecosystem code; and one flat file (simpler format and additional information on ecosystem name; gridcell area; and medium, revised medium, minimum, and maximum estimates of carbon density) of 16.8 MB uncompressed or 2 MB compressed.