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Ecoregion Description
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The Central Appalachian ecoregion stretches from central Pennsylvania through West Virginia, Maryland, Virginia, and Kentucky and into northern Tennessee (Omernik, 1987). The ecoregion covers approximately 59,800 km2 (23,089 mi2) (fig. 1) and is about 89 percent forested. It is primarily a high, dissected, rugged plateau composed of sandstone, shale, conglomerate, and coal. Local relief varies from less than 15 m (50 ft) to more than 594 m (1,950 ft), and the highest mountain elevations range from about 366 to 1,402 m (1,200 to 4,600 ft) (Woods and others, 1996). The rugged terrain, cool climate, and infertile soils limit agriculture and result in a mostly forested land cover. A mixed mesophytic forest with areas of Appalachian oak and northern hardwood forest cover the high hills and low mountains. Coal mining is common in the ecoregion and is one of the major drivers of change. The agricultural lands of the ecoregion are located in the valleys, where the growing season can last up to 165 days (Woods and others, 1996). The main agricultural activities include livestock and dairy farming and Christmas trees growing on plantations. The climate of the Central Appalachians is variable because of topographic influences in the region. Precipitation is distributed rather uniformly throughout the year, but the late summer and early fall seasons tend to be drier, with an average annual precipitation of about 1,125 mm (45 in) (Raitz and Ulack, 1984).
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Figure 1: Central Appalachians and surrounding ecoregions. The 32 randomly selected 100-km2 sample blocks are shown along with land use/land cover from the 1992 National Land Cover Dataset. Click to enlarge image
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Contemporary Land Cover Change (1973 to 2000)
The overall spatial change in the Central Appalachians was 9.1 percent from 1973 to 2000 (fig. 2). This was a moderate amount of change in comparison to the other eastern ecoregions. Most of the change was closely tied to coal mining in the ecoregion. An estimated 5.9 percent of the ecoregion changed only once, and the percentage of area undergoing multiple changes was estimated at 3.2 percent (table 1). Most of the multiple-change areas reflected different stages of land cover, including forest, mechanically disturbed, mining, and grassland/shrubland, as coal mines became established, expanded, an then eventually closed down and were abandoned or reclaimed. The sample blocks with the highest change were concentrated in coal mining regions. The total change per time period ranged from 2.5 percent to 4.1 percent (table 2). Our average annual rates of change show that the 1986 to 1992 period had the highest rate of change with a rate of 0.6 percent per year (table 2 and fig. 3). This was likely because of a resurgence of coal mining in West Virginia in the 1990s (Fox, 1999).
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Table 1: Amount of overall spatial change detected in ecoregion and proportion of ecoregion that experienced change during one or multiple time periods
Table 2: Raw estimates of percent change in ecoregion computed for each of four time periods and associated margin of error at 85-percent confidence level
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Figure 2: The overall spatial change in all Eastern U.S. ecoregions. Each bar chart shows the proportion of the ecoregion that experienced change on 1, 2, 3, or 4 dates. Click to enlarge image
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Figure 3: The estimates of land cover change per time interval normalized to an annual rate of change as compared to other ecoregions. Central Appalachian ecoregion is highlighted in black. Click to enlarge image
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The mining, grassland/shrubland, and forest classes had the most change during our study period (table 3). Mining nearly doubled in area from 1.7 percent of the ecoregion in 1973 to 3.2 percent in 2000. Conversely, forest decreased from 86.6 percent to 83.3 percent. The grassland/shrubland category increased throughout the study period, as old mining areas transitioned back to forest. Agriculture decreased slightly because of abandonment and subsequent conversion back to forest. Developed lands increased slightly over the four time periods, in contrast to the population of the ecoregion, which has steadily decreased since the 1980s (fig. 4).
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Table 3: Proportion of ecoregion covered by each land cover class during each of five mapped dates
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Figure 4: Central Appalachian population 1950 to 2000 (U.S. Census Bureau). Click to enlarge image
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Figure 5 shows the net changes in land cover classes in the ecoregion over the study period. The changes were relatively minor until the 1992 to 2000 period when there was resurgence in forest clearing for mining activities. The leading land cover conversions were also all related to coal mining in the ecoregion. Forest to mining was the top conversion during all time periods, ranging from 450 to 1,099 km2 (table 4). During every time period, at least 65 percent of all changes were connected to mining activities in the ecoregion.
Figure 5: Per period net change for each land cover class. Areas above zero represent net gains for a land cover class, while areas below represent a net loss. Click to enlarge image
Table 4: Leading land cover conversions during each of four time periods
1 Kristi L. Sayler – U.S. Geological Survey, Center for Earth Resources Observation and Science, Sioux Falls, SD 57198
References
Fox, J., 1999, Mountaintop removal in West Virginia—an environmental sacrifice zone: Organization and Environment, v. 12, no. 2, p. 163-183.
Omernik, J.M., 1987, Ecoregions of the conterminous United States: Annals of the Association of American Geographers, v. 77, no. 1, p. 118-125.
Raitz, K.B., and Ulack, R., 1984, Appalachia, a regional geography—land, people, and development: Boulder, Colo., Westview Press, 396 p.
U.S. Census Bureau, various years, at http://www.census.gov/prod/www/abs/decennial/index.htm.
Woods, A.J., Omernik, J.M., Brown, D.D., and Kiilsgaard, C.W., 1996, Level III and IV ecoregions of Pennsylvania and the Blue Ridge Mountains, the Ridge and Valley, and Central Appalachians of Virginia, West Virginia, and Maryland: EPA/600/R-96/077, U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Corvallis, Oreg., 50 p.
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U.S. Department of the Interior |
U.S. Geological Survey
