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- Info
Historical and ecological roles of disturbance in eastern North American forests: 9,000 years of change
| Author: |
Lorimer, C.G. |
| Date: |
2001 |
| Periodical: |
Wildlife Society Bulletin |
| Abstract: |
Recent declines in habitat suitable for early successional wildlife species are interpreted in a broad historical context, using several types of scientific and historical evidence to estimate changes in amount of young forest habitat in presettlement and post-settlement eras. A major contrast in disturbance regimes between northern mesophytic hardwood forests and the oak-pine forests of the central and southern United States is evident for several thousand years before European contact. Catastrophic wind disturbance is a dominant feature in northern hardwood forests, but frequency is fairly low except in areas affected by Atlantic hurricanes. Most northern hardwood regions were dominated by old-growth forest in presettlement times, with young forest habitat (up to 15 years old) occupying <1% to 13% of the landscape in different states. In contrast, fire was a dominant force in shaping species composition and structure of oak-hickory and oak-pine forests with savanna and grassland habitat occupying up to 65% of the landscape in some midwestern regions. Numerical estimates of the presettlement extent of young forests and savanna habitat are not possible for the Atlantic slope and Gulf regions, but the composition and structure of the vegetation seemed to bear the imprint of frequent fires in most areas where evidence is available. Comparison of historic fire frequency with modern lightning fire data suggests that humans caused most of these fires. Young forest habitat reached a peak of up to 55-60% of the forest cover in most states in the late 19th century because of logging, wildfires, fuelwood cutting, and farm abandonment, but has since declined to 20% or less in many regions. |
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