Fragmented Forests

Fragmentation affects the full range of ecosystem benefits provided by forests. Photo by U.S. Environmental Protection Agency.

The Southern Forest Resource Assessment published by the Southern Research Station defined forest fragmentation as the breaking up of large, contiguous (touching one another) forested tracts into smaller or less contiguous tracts. This means that forests become islands or peninsulas — patches of woods disconnected from one another by roads, farms, suburbs, cities, and other human activities.

Forest fragmentation affects a wide range on ecosystem services, defined as the benefits that forests provide to us. In addition to providing wood products, fuel, medicine, and recreation, forests:

  • Clean water and air;
  • Provide habitatĀ for a huge diversity of life forms;
  • Take up carbon dioxide and produce oxygen;
  • Regulate climate by sequestering carbon;
  • Maintain the health of soil;
  • Absorb and detoxify pollutants; and
  • Provide settings for a wide range of recreational activities;

When forests are divided into smaller and smaller parcels, the biological diversity of native animals and plants is diminished, water cycles are altered, nonnative invasive plants and animals are introduced, and air and water quality are affected. Forests weakened by fragmentation become more susceptible to damage from insects and diseases, and coming under stress, often degenerate into a condition of chronic ill health.

Forest fragmentation creates “edge effects” in areas where forests meet roads and lawns. As the proportion of undisturbed interior forest to edges decreases, some wildlife species decline. Others, such as white-tailed deer, increase and become seen as pests by those who live near forest edges.

In the South, the highest concentrations of intact interior forests are on public lands in the Blue Ridge Mountains, the Cumberland Plateau, and the Allegheny Mountains. The lands surrounding these intact forests are, unfortunately, highly susceptible to fragmentation from roads and increasing development. Other areas especially susceptible include the Ozark and Ouachita Mountains in Arkansas, the Piedmont of North Carolina, and areas in the Mississippi River Valley, west Coastal Plain, and Interior Low Plateau.

Additional reading:

Macie, Edward A.; Hermansen, L. Annie, eds. 2002. Human influences on forest ecosystems: the southern wildland-urban interface assessment. Gen. Tech. Rep. SRS-55. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 159.

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