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5.3 Forest Conditions

5.3.1 Forest Population Density

Forest population density (FPD) measures the number of people per square mile (ppsm) of forest in counties. The index ranges from about 20 ppsm in very rural areas of the South to more than 1,000 in urbanized areas. We consider 1,000 ppsm a "saturated" condition and cap FPD values at 1000. As expected, FPD is highest near large cities (Figure 15A). Florida has the highest concentration of these saturated areas. Population density is very high throughout Florida and forest cover is low in the southern half of the State. The largest contiguous area of very low FPD is in southwestern Alabama, where more than 20 counties have an FPD of less than 50 ppsm.

Three areas of the South with interState highway corridors had relatively high FPD values in 1992: the I-85 corridor from Raleigh/Durham, NC, to Atlanta, GA; the I-65 corridor from Birmingham, AL, to Nashville, TN; and the I-81 corridor from Chattanooga, TN, to Wytheville, VA. On the periphery of the region in northern Kentucky and Virginia and along the Gulf Coast, FPD's were also relatively high in 1992.

Forecasts to 2020 indicate continued outward growth of the urban centers of the South. A characteristic "doughnut" pattern of growth emerges around the cities of Atlanta, Nashville, Charlotte, and Washington (Figure 15B). Expansion in FPD would also be concentrated along the Atlantic Coast in South Carolina and Florida, and along the Gulf Coast. Figure 16 shows the shift in the population profile of counties in the South. There is a strong movement to the right as 82 counties move out of the most rural category (FPD=0-100) and 52 counties move into the saturated category (>900).

5.3.2 Landscape Patterns

Maps of land cover in the early 1990's (Figure 17) reveal that, overall, the South is heavily forested and that the distribution of forest cover is highly variable. Two areas of the South have large blocks of counties with forest cover in excess of 80 percent of the landscape. One is the Blue Ridge Mountain Province from northern Georgia to the North Carolina-Virginia border. The other is the Cumberland Plateau/Southern Allegheny region stretching from central Tennessee (just west of Knoxville) to the Ohio River.

Areas with somewhat less forest cover than the Blue Ridge, but still substantial shares, are the Southern Appalachian Piedmont and the Gulf Coastal Plain (including nearly the entire State of Alabama). Even in the urbanizing areas of the Southern Appalachian Piedmont, forest covers a majority of the land. The other area of substantial contiguous forest cover is west of the Mississippi River in a block that stretches north from central Louisiana to the Ozark Mountains.

Forest cover does not dominate in important agricultural areas of the South. Agriculture is especially dominant in the Mississippi Alluvial Valley, in the northern and western portions of Kentucky, and in the southwestern corner of Georgia (Figure 17B).

Developed human uses are especially high in two areas. One is the "Piedmont Crescent" stretching from Raleigh/Durham, NC, to Atlanta, GA. The other is peninsular Florida. Other areas with substantial clusters of urban cover are Nashville and Knoxville, TN, and Washington, DC. All of these cities are surrounded by relatively large "footprints" of urban use.

A high proportion of interior forest in a county is an indicator of relatively contiguous forest. The highest concentrations of interior forest at the fine scale (7-ha neighborhood) are found in the Blue Ridge Mountains and in the Cumberland Plateau/Allegheny Mountain sections of the South (Figure 18A). The Smokey Mountain National Park and a part of the Daniel Boone National Forest in Kentucky (just west of where Virginia, West Virginia and Tennessee meet) are the cores of these two areas. Other areas where the share of interior forest is high include the Ouachita Highland/Ozark Mountain region of Arkansas, a region just north of the Mobile Bay, and the Apalachicola area in the Panhandle of Florida. All of these areas include relatively high shares of land in public ownership.

The broad-scale measure of interior forest (56-ha neighborhood) highlights the relative scarcity of large contiguous areas of forest cover. At this scale, blocks of interior forest are found only in far western Virginia, the Cumberland Plateau, the Blue Ridge, and the mid-Coastal Plain west of the Mississippi River.

Forests that are highly fragmented are shaped primarily by human influences. The Southern Appalachian Piedmont has a relatively high proportion of land in a edge-dominated category, especially in North Carolina (Figure 19). Two other contiguous blocks are in an area spanning northern Mississippi and western Tennessee and an area west of the Cumberland Plateau between Alabama and Cincinnati, OH. In both of these areas, agricultural cover types break up the forest cover into small patches and reduce the amount of interior forest.