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- Info
Presettlement fire regimes in southeastern marshes, peatlands, and swamps
| Author: |
Frost, Cecil C. |
| Periodical: |
In: Cerulean, Susan I.; Engstrom, R. Todd, eds. Fire in wetlands: a mangement perspective. Proceedings of the Tall Timbers fire ecology conference; 1993 November 3-6; Tallahassee, FL: Tall Timbers Research Station |
| Abstract: |
Presettlement fire regimes in wetland vegetation can be deduced or reconstructed by synthesizing knowledge of fire behavior on adjacent uplands with information about soils, salinity, landscape factors, remnant vegetation, and historical records. Presettlement fire-return intervals in different parts of the southeastern wetland landscape ranged from nearly annual, up to 300 years, and vegetation was distributed accordingly along this fire frequency gradient. Prediction of vegetation stature and species composition in relation to fire can be made with some confidence in marshes, in the wettest swamps, and on uplands. In large peatlands, however, stochastic factors created a shifting mosaic before European settlement, in which any one of several competing communities could exist for a time on the same soil series, depending upon environmental conditions at time of burn. Before modern fire suppression, peatland vegetation was controlled primarily by master gradients of fire frequency and organic matter depth. There was a third, minor fertility gradient. Distribution of peatland vegetation types along these gradients is complex but is summarized here using a table of 32 cells defined by 8 fire frequency classes and 4 organic soil depths. While many marshes and swamps in the southeast differ little form their presettlement species composition, few peatlands, even those considered natural areas, have escaped major alteration in species dominants. A large percentage or modern pocosins can be shown to be successional from canebrake and other frequent-fire types in the absence of fire. At the other end of the spectrum, in Virginia and North Carolina, large areas now categorized as pocosin were dominated by white cedar (Chamaecyparis thyoides), and infrequent-fire type, as late as 1900. In most cases, major shifts in vegetation type were selected for unwittingly in the process of fire suppression or logging. When designing a fire management regime in peatlands today, the method selected will determine whether the treatment will perpetuate what is there (the usual choice) or a return to one or more of the presettlement community types. |
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