Land Cover Trends Project


Overview/Summary  •   Ecoregion Framework  •   Sampling Strategy  •   LandSat Source Data   •   Classification System  •   Interpretation Process  •   References

Ecoregion Framework

A central premise of the project strategy was that EPA Level III ecoregions can provide an ideal geographic framework for characterizing regional LULC change. The ecoregion boundaries used were originally defined by Omernik (1987) and then revised in 1999 (USEPA, 1999). The spatial boundaries were developed by synthesizing information on climate, geology, physiography, soils, vegetation, hydrology, and human factors, such that the ecoregions reflect patterns of land-cover and land-use potential that correlate with patterns visible in remotely sensed data. This set of factors makes ecoregions suitable to tell regional stories of change, highlighting how land-use/land-cover patterns, disturbance types and frequencies, environmental issues of concern, and management practices and consequences that are similar regionally yet differ across the country. Land Cover Trends also employs this framework because ecoregions (1) provide a means to localize estimates of the rates and driving forces of change, (2) play a significant role in determining the range of current LULC types, and the trajectories of land use and land cover that may take place in the future, and (3) provide a framework that can be extended globally.

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