National Land Cover Trends Program

Figure 1. Level III Ecoregions of the United States.
Figure 2. Trends Status Graphic w/change rates from EROS.

Land Cover Trends is a national project that describes for specific geographic areas within the conterminous United States the rates, causes, and consequences of land use and land cover change for the period 1972 to 2000. The project relies on sampling through both time and space (geographic area). The geographic areas being studied are the Environmental Protection Agency's (EPA) Level III Ecoregions of the United States (fig 1.) Five time intervals-1973, 1980, 1986, 1992, and 2000-were selected for evaluation using manual interpretation of Landsat Multispectral Scanner, Thematic Mapper, and Thematic Mapper Plus imagery to map change. These time intervals were evaluated using a modified 11-class Anderson system for image interpretation. Once mapping is completed for an ecoregion, land cover change statistics are generated and a full descriptive change matrix is produced (fig 2).

The Western Geographic Science Center has completed mapping in the following ecoregions: Mojave Basin and Range, Central Basin and Range, Puget Lowlands, Wilamette Valley, Sierra Nevada Mountains, California Central Valley, Northern Basin and Range, Central and Southern Chaparral and Oak Woodlands, Southern California Mountains, and Klamath Mountains ecoregions. The Southwest Geographic Science Team has completed work on the Chihuahuan Deserts and Sonoran Basin and Range ecoregions. We are currently in various stages of work in the Cascades, Snake River Plain, Eastern Cascades, and Arizona/New Mexico Mountains ecoregions.

Point of Contact: Benjamin M. Sleeter (Geographer)

Publications and Websites:

Central Valley Ecoregion Summary Report: http://geography.wr.usgs.gov/science/docs/Ecoregion7_Summary_webversion.pdf

Central Basin and Range Ecoregion Report: http://pubs.usgs.gov/sir/2006/5288/

Sierra Nevada Ecoregion Report:http://pubs.usgs.gov/sir/2007/5011/.

Mojave Basin and Range Ecoregion Report: http://pubs.usgs.gov/sir/2006/5098/

Eastern Region Synthesis Report: http://eros.usgs.gov/LT/coverpage.html

Southern California Mountains Ecoregion Report: http://pubs.usgs.gov/sir/2007/5235/