Land Cover Trends Task

Project Introduction

Land Cover Trends Geographers at Work Land Cover Trends Geographers conduct research that is a subset of the work of the Geography Discipline. Their research goals are to determine: (1) how the Nation’s land cover has changed over time; (2) what forces have caused these changes; and (3) what are the consequences of these changes. To achieve these goals, Trends Geographers perform several tasks. They visit each ecoregion to observe the land cover of randomly selected sample sites and of the ecoregion as a whole. Next, data are assembled and prepared to determine the land cover change for each sample site during the study period. The Trends Geographers interpret and analyze these data, which include: Landsat satellite imagery, aerial photography, topographic maps, field notes, and ancillary socioeconomic data. State and local land use/land cover data are sometimes used. Often, some of the data must be scanned or otherwise transformed so it can be analyzed using image processing systems and geographic information systems (GIS). Once a Trends Geographer has completed the interpretation and analysis of a specific sample site, the work is peer reviewed and revised if necessary. When all the sample sites in an ecoregion have been interpreted and analyzed, the research results are documented in a professional, peer-reviewed paper.

The USGS Land Cover Trends Project is a joint effort between the U.S. Geological Survey, the U.S. Environmental Protection Agency, and National Aeronautics and Space Administration (NASA) to study the rates, causes, and consequences of land use and land cover change in the conterminous United States for the 1973 – 2000 period.  Eighty-four “ecoregions”, each containing a geographically distinct assemblage of environmental conditions, natural communities, and species, provide a geographic framework for the project and serve as separate reporting units.  A sampling approach using randomly selected 10-km by 10-km sample blocks is used to estimate land cover change in each ecoregion.  Historical Landsat multispectral scanner (MSS) and thematic mapper (TM) satellite imagery, along with historical aerial photography, topographic maps, field observations, and socioeconomic data are used to derive land cover maps for five separate dates (1973, 1980, 1986, 1992, and 2000).  The sample block land cover data are used to analyze the spatial, temporal, and sectoral dimensions of change. 

Goals and Objectives:

• Estimate the types, rates and temporal variability of change in each ecoregion.
• Document regional driving forces and consequences of change.
• Prepare a national synthesis of land cover change.

Project History – The Land Cover Trends Project originated at the USGS EROS Data Center under the leadership of Thomas R. Loveland, PhD., who serves as the project leader. The support of the U.S. Environmental Protection Agency (Landscape Ecology Branch, Las Vegas), which continues today, has been instrumental in the project's progress and success. The support of the NASA Land Cover Land Use Change Program is also an important element of the Trends project. The Eastern Geographic Science Center (EGSC) Land Cover Trends task began in FY2002, and is the EGSC contribution to this project.

EGSC Land Cover Trends Team Members

Top