Land Cover Trends Project

Blue Ridge Mountains

By Janis L. Taylor, Rachel Kurtz 1

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map of Blue Ridge Mountains

Figure 1.  The Blue Ridge ecoregion. The underlying land cover is taken from the 1992 National Land Cover Database (Vogelmann and others, 2001).

Ecoregion Description

 

The Blue Ridge Mountains ecoregion is located in the southern Appalachian Mountains, and is the easternmost of the Appalachian highland ecoregions (fig. 1). At more than 1100 km long and ranging between 8 and 80 km wide, it covers approximately 47,791 km2 (18,452 mi2). The ecoregion is primarily forested with cool summers and cold winters. Almost one-third of the ecoregion is under public ownership, including two National parks—the Great Smoky Mountains National Park and Shenandoah National Park, the Blue Ridge Parkway, seven National forests, and 29 wilderness areas (Nash, 1999). Areas within the Great Smoky Mountains National Park have been declared an International Biosphere Reserve because of the high number of endemic species of flora and fauna (Bousquet, 2000). The overall landscape is a mosaic of large continuous blocks of forest intermixed with agriculture and dotted with small parcels of developed land.

 

Change from 1973 to 2000

 

The Blue Ridge Mountains ecoregion is stable. The overall areal change in land cover—the percentage of land area within the ecoregion where land cover changed at least once between 1973 and 2000—was 2.0 percent, the lowest of all Eastern U.S. ecoregions (fig. 2). Three fourths of the converted land changed only one time, while one-fourth changed twice (table 1).

Estimated changes in each of the time periods selected for this study were low, ranging from 0.5 percent in the 1973 to 1980 period to 0.9 percent in the 1992 to 2000 period (table 2). The estimates of land cover change have an associated margin of error that is shown in table 2. After normalizing the land cover change per period to an annual rate of change to avoid comparison of unequal time intervals, change was lowest in the 1980 to 1986 period, at 0.07 percent per year, and highest in the 1992 to 2000 period, at 0.11 percent per year (fig. 3).

Three classes of land cover (forest, agricultural land, and developed land) account for 99 percent of the ecoregion. Table 3 lists the percentage of each individual land cover class during each of the five mapped dates. Forest is the most common cover and makes up nearly 80 percent of the ecoregion. Over the entire study period, forest cover decreased from 79.6 percent of the ecoregion in 1972 to 78.3 percent in 2000, a 1.3 percent decrease. Changes to forest cover included both unidirectional conversions and cyclical conversions during the study period. Some forest was converted to developed land, while some was harvested for timber, and then returned to forest in subsequent years. Agriculture was the second most common land cover, occupying approximately 13.7 percent of the ecoregion (fig.4). Over the entire study period, agricultural cover remained relatively stable with minor gains and losses in each time period. Developed land, the third most common land cover, increased 1.1 percent, from 6.1 percent in 1972 to 7.2 percent in 2000 (figs. 5 and 6). 

The transition from forest to developed land dominated three of the four periods (1973 to 1980, 1980 to 1986, and 1992 to 2000) (table 4) (fig. 7).  The largest conversion of this type occurred from 1992 to 2000, when 192 km2 of forest was converted to some type of developed land (fig. 8). Between 1986 and 1992, the major land cover conversion was from forest to mechanically disturbed, when 87 km2 of forest was cut, a likely result of commercial timber harvesting for pulpwood used to produce paper and packaging materials (SAMAB 1996).

Overall, little change occurred in the ecoregion between 1973 and 2000. Most of the land cover change that did occur was to developed land. Existing urban areas expanded and exurban development increased. According to the U.S. Census Bureau (2000), seasonal housing has been increasing in high proportions in Avery and Watuga Counties, North Carolina. Between 1970 and 2000, population within the ecoregion increased by 63 percent, almost double the national increase of 34 percent. The ecoregion is also experiencing an increase in tourism and recreational activities such as golf and skiing. This amenity-rich area draws seasonal residents in the summer for a respite from the warmer and more humid South and in the winter for snow-related, winter recreation (Gade and others, 2002).

 

References

 

Bousquet, Woodward S., 2000, Outdoor Recreation, in Orr, Douglas M., Jr., and Stuart, A.W., The North Carolina atlas—portrait for a new century: Chapel Hill, N.C., The University of North Carolina Press, p. 409-433.


Gade, O., Rex, A.B., Young, J.E., and Perry, L.B., 2002, North Carolina—people and environments 2d ed.: Boone, N.C., Parkway Publishers, Inc, 602 p..

Nash, Steve, 1999, Blue Ridge 2020—an owner's manual: Chapel Hill, N.C., The University of North Carolina Press, 211 p.

Southern Appalachian Man and the Biosphere (SAMAB), 1996, The Southern Appalachian Aassessment: Atlanta, Ga., U.S. Department of Agriculture, Forest Service, Southern Region, vols. 1-5. 

U.S. Census Bureau, 2000, GCT-H5 General housing characteristic—2000,  accessed November 11, 2004,

Vogelmann, J.E, Howard, S.M.,  Yang, L., Larson, C.R., Wylie, B.K., and Van Driel, N., 2001, Completion of the 1990s National Land Cover Data Set for the coterminous United States from Landsat Thematic Mapper data and ancillary data sources: Photogrammetric Engineering & Remote Sensing, v. 61, p. 650-662.



[1] SAIC TSSC, work performed under U.S. Geological Survey contract 03CRN001 at U.S. Geological Survey, Center for Earth Resources Observation and Science, Sioux Falls, SD 57198

[2] U.S. Geological Survey, Center for Earth Resources Observation and Science, Sioux Falls, SD 57198

[3] U.S. Geological Survey Visiting Scientist, Center for Earth Resources Observation and Science, Sioux Falls, SD 57198; Geography Professor, South Dakota State University, Brookings, SD 57007

Table 1.  Amount of overall spatial change detected in ecoregion and proportion of ecoregion that experienced change during one or multiple time period

 

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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

 

[Estimates of change per period are normalized to an annual rate of change for each of the four time periods]

 

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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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Table 4.  Leading land cover conversions from 1973 to 2000 ranked by greatest to least area changed

 

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Figure 1.  The Blue Ridge ecoregion. The underlying land cover is taken from the 1992 National Land Cover Database (Vogelmann and others, 2001).

 

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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.

 

 

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Figure 3.  The estimates of land cover change per time interval normalized to an annual rate of change.

 

 

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Figure 4.  Tobacco field adjacent to a school in Barnardsville, North Carolina (photograph)

 

 

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Figure 5.  The percentage of net land cover change in each time interval.

 

 

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Figure 6.  Homes built along the ridge-line near Boone, North Carolina (photograph)

 

 

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Figure 7.  Strip mall off Interstate 40, at newly-built exit 64 near Asheville, North Carolina (photograph)

 

 

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Figure 8.  Penrose quarry in Lumpkin County, Georgia (photograph)

 

 

 

 



[1] SAIC TSSC, work performed under U.S. Geological Survey contract 03CRN001 at U.S. Geological Survey, Center for Earth Resources Observation and Science, Sioux Falls, SD 57198

[2] U.S. Geological Survey, Center for Earth Resources Observation and Science, Sioux Falls, SD 57198

[3] U.S. Geological Survey Visiting Scientist, Center for Earth Resources Observation and Science, Sioux Falls, SD 57198; Geography Professor, South Dakota State University, Brookings, SD 57007

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