Land-cover change in the conterminous United States from 1973 to 2000

https://doi.org/10.1016/j.gloenvcha.2013.03.006Get rights and content
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Highlights

  • Changes in land use and cover affected 8.6% of the conterminous United States between 1973 and 2000.

  • Change impacted 16.6% of US forests with net forest cover declining by 4.2%.

  • Agricultural land declined by 4.2% while grass/shrubland increased by 2%.

  • Developed areas increased by 33%.

  • Natural and anthropogenic ecosystem disturbance impacted 236,000 km2.

Abstract

Land-cover change in the conterminous United States was quantified by interpreting change from satellite imagery for a sample stratified by 84 ecoregions. Gross and net changes between 11 land-cover classes were estimated for 5 dates of Landsat imagery (1973, 1980, 1986, 1992, and 2000). An estimated 673,000 km2(8.6%) of the United States’ land area experienced a change in land cover at least one time during the study period. Forest cover experienced the largest net decline of any class with 97,000 km2 lost between 1973 and 2000. The large decline in forest cover was prominent in the two regions with the highest percent of overall change, the Marine West Coast Forests (24.5% of the region experienced a change in at least one time period) and the Eastern Temperate Forests (11.4% of the region with at least one change). Agriculture declined by approximately 90,000 km2 with the largest annual net loss of 12,000 km2 yr−1 occurring between 1986 and 1992. Developed area increased by 33% and with the rate of conversion to developed accelerating rate over time. The time interval with the highest annual rate of change of 47,000 km2 yr−1 (0.6% per year) was 1986–1992. This national synthesis documents a spatially and temporally dynamic era of land change between 1973 and 2000. These results quantify land change based on a nationally consistent monitoring protocol and contribute fundamental estimates critical to developing understanding of the causes and consequences of land change in the conterminous United States.

Keywords

Land use
Land cover
Ecoregions
Landsat
Urbanization
Forestry
Agriculture

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