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Changes in Forest Land Area in the South

Forest land, as defined by FIA, is at least 10-percent stocked by trees of any size or formerly having had such tree cover and is not currently developed for nonforest use. The minimum area considered for classification is 1 acre. Estimates of forest land include all reserved, woodland, and timberland acres in the 13 Southern States.

Although actual inventories of forest land in the United States did not begin until the 1930s, estimates of forest land for individual Southern States are available from RPA (Smith and others 2001) as far back as 1630 (table 16.1). These early estimates are based on the current area of forest land and on accounts of land clearing and settlement by Native Americans and European settlers. This "original forest" area is presented only for comparison with what remains today.

The area of forest land in the South has changed dramatically since European settlement. It is estimated that there were 354 million acres of forest land in 1630 (fig. 16.1). Descriptions and anecdotal accounts of the appearance of the forests at that time reveal a landscape very different from that which we see today (chapter 24). By 1907, the area of southern forests had declined by one-third to 236 million acres. Much of the decline was due to clearing for homes, crops, and pasture. The continued influx of people, the lack of a concerted effort to regenerate cleared forest land, and uncontrolled wildfires led to further declines over the next three decades, and by 1938 forests occupied 221 million acres.

The Civilian Conservation Corps, along with the Agricultural Conservation Program of the 1930s, and the Soil Bank Program of the 1950s, helped return millions of acres of idle pasture and eroded cropland to forest (U.S. Department of Agriculture Forest Service 1988). Between 1938 and 1963, area of forest land in the South rose by 7 million acres to 228 million. This gain was short-lived, however, and by 1982 forest area dropped to 218 million acres, as 10 million acres of forest land were cleared for farming and development. The loss of forest land continued over the next 7 years, and the total area declined to a low of 212 million acres. To help reverse this latest downward trend, the Conservation Reserve Program was established in 1985. It provided farmers with monetary incentives to plant trees on highly erodible cropland. These incentives and other efforts apparently had the intended affect. By 1999, southern forest area had increased by 3 million acres to 215 million acres. However, since 1907 the South has lost nearly 21 million acres, or 9 percent of its forest land.

Diversions of forest land to agriculture and urbanization—Since the 1930s, FIA has tracked the changes in the area of forest land by classifying current and previous land use at each sample location. Acres that were previously forested but are now cleared for agriculture or developed for some other nonforest use are called diversions. Diversions to agriculture or an urban land use account for the majority of the losses of forest land in the South. Average annual diversion of forest land to these nonforest land uses between 1968 and 1990 are shown in figure 16.2. Data for figure 16.2 were compiled from published FIA reports on file at the Southern Research Station, Knoxville, TN. Data for Kentucky were not available.

The area of cropland and pasture peaked in the 1920s and has been declining since (U.S. Department of Agriculture Forest Service 1988). The reduced demand for agricultural land is reflected in the rate at which forest land was cleared for crops and related uses. In 1968, forest land was being converted to agriculture at the rate of 1.1 million acres per year (fig. 16.2). By 1990, the annual rate of conversion had declined to 308,000 acres.

In contrast, the rate of forest land lost to urbanization, until recently, has increased steadily, closely following the upward trend in the region's population (chapter 6). FIA estimates show that 377,000 acres of forest were lost to urban and other related land uses in 1968, and by 1978 the annual rate of loss had increased to 508,000 acres (fig. 16.2). By 1983 and 1984, urbanization was removing forest land from the South's timber base at an average rate of 540,000 acres per year, surpassing agriculture as the primary cause of loss of forest land. The rate of urbanization has declined in recent years, but in 1990 diversions of forest land to urban and related uses remained substantial, amounting to 406,000 acres. Cumulatively, forest land converted to agriculture or urban land uses during this 23-year period total 25 million acres. These figures likely include acres that have undergone more than one transition.

The fact that urbanization is apparently the primary reason for reductions in forest land holds important implications. Land clearing for crops and pasture is often transitory, as economics, owner goals, and other factors dictate land use over time. For instance, timberland acres originally cleared for cotton over 50 years ago are once again supporting stands of hardwoods and pine. The same cannot be said for diversions of forest land to urban land uses, which are usually permanent.

Total change in forest land: additions and diversions—While losses to urbanization and agriculture were occurring, there were also concerted efforts throughout the South to regenerate nonforest land. Figure 16.3 shows the average annual change in total area of forest land in the South between 1970 and 1990. Total diversions include the acres of forest land converted to water, plus the diversions to agricultural or urban and other land uses already discussed. The primary source of additions to forest land is idle cropland or pasture, which regenerated naturally or was planted or seeded.

Average annual diversions to nonforest decreased steadily between 1970 and 1990, but they consistently outpaced the rate of additions (fig. 16.3). In 1970, total diversions removed 1.8 million acres from the timber base. Additions amounted to 787,000 acres, and the South experienced an average net loss of over 1 million acres of forest in that year. The rate at which nonforest was being regenerated reached a peak in 1972 at 829,000 acres. The annual rate of additions declined over the next 6 years, and the 1972 level was not surpassed until 1979 and 1980, when 839,000 acres were reforested annually. Cumulatively, 9 million acres of forest land were added between 1970 and 1980. The annual rate of diversions continued to slow, but still exceeded additions. By 1980, a total of 15 million acres of forest land had been diverted to a nonforest classification, resulting in a net loss of 6 million acres regionwide over the 10-year period. The gap between the rates of diversion and additions was closing, however. Evidence suggests that Federal Government initiatives, such as the Forestry Incentives Program of the 1970s, were helping to slow the rate of deforestation and increase the rate of planting and reseeding on cleared and other nonforest land.

From 1980 to 1986, the average annual rate of diversions remained fairly stable at around 1 million acres. Annual additions to forest land rose from 839,000 acres in 1980, to 972,000 acres by 1986. Cumulative losses of forest since 1980 amounted to 6.6 million acres, but additions totaled 5.5 million acres, for a net loss of 1.1 million acres over the period. There also is evidence that the more recent Federal incentives, such as the Conservation Reserve Program established in 1985, have helped slow the rate of diversion. A milestone was reached in 1987 when the South gained more forest land than it lost. That year, 1 million acres were added to the timber base, while 953,000 acres were diverted to other uses. By 1990, nonforest land was being converted to forest at a rate of 1.3 million acres, and diversions out of the timber base declined to 841,000 acres annually. Cumulative additions over the last 4 years of the period amount to 4.9 million acres, and diversions totaled 3.5 million acres.

The most recent year in which the additions/diversions data collected by FIA are available for each State is 1990. Current and future inventories will provide additional data to track the changes and trends in the South's forest land area in all 13 States. However, the increase of 3 million acres of forest between 1989 and 1999 shown in figure 16.1 suggests that the general trend in additions and diversions witnessed between 1987 and 1990 has continued over the past decade.