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Introduction
The Global Ecosystems Database was compiled and published by NGDC as a
result of collaboration with the U.S. Environmental Protection Agency in
the early 1990's. Individual data layers have been contributed by many
scientific laboratories and individuals. Two compilations of these datasets
were published as CD-ROM products; Disc-A (September 1992), and Disc-B
(November 1997). These data products have been combined into a single product
with digital documentation (GED-II). Altogether the database contains 30
datasets, each of which is an originally authored work resulting from or
intended for use in global and regional biogeographical modeling.
Each dataset is presented in a geographically integrated form within three databases
defined by geographic area and projection. These are: Global Geographic
(GLGEO), in a Cartesian geodetic (latitude/longitude) projection; United
States Albers (USALB), in an Albers Equal Area Conic projection; and South-East
Asia Geographic (SEAGEO), in a Cartesian geodetic (latitude/longitude)
projection. The integration environment is constituted by conventional
Geographic Information Systems (GIS) data structures for both raster and
vector digital maps. The distribution format is an open (non-proprietary)
format that is easily converted to various formats using tools provided
by NGDC or user programs. It is also fully compatible with an existing
GIS (IDRISI version 4+ and IDRISI for Windows version 2,
from Clark University, Worcester, Massachusets).
Each file has been prepared for optimal usability for analysis, given
the current state of data development. Parameters have been chosen for
their potential use in integrated studies of the global environment with
particular focus on climate, soils, human disturbance, and vegetation;
under present conditions and under global warming scenarios for the USA.
Georeference and terrain data are also provided for significant land features.
Spatial resolution of the data ranges primarily from 10-minutes to 1-degree,
with a few variables at higher resolutions and data for GCM models at coarser
resolution. This range is considered suitable for modeling climatic and
other environmental determinants of global and continental scale biogeographical
regions, and analyzing broad changes in vegetation cover and distribution.
The database is available on-line, for browsing and downloading
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