Prescribed Fire and Pond Cypress Wetlands

A decrease in fire frequency, nearly to the point of excluding fire from cypress wetlands has been the outcome of many prescribed fire programs. Many wetlands have historically been protected from fire by plowing fire lines around the wetland (Frost, Walker and Peet 1986). Recently though, the importance of fire to the ecology of these wetlands and the detrimental effects of fire lines that “protect” these wetlands has been recognized. The practice of protecting wetlands from fires stems from the misconception that forested wetlands shouldn’t burn and from the practical concerns of smoke management and fire control.

When implementing a prescribed fire program in cypress wetlands a number of issues should be considered:

1. For the maintenance of the natural community must be balanced with practical limitations in burning. Examination of wetlands to determine the risk of ground fires, i.e., how much organic soil or peat is actually present, and the water content of peat throughout the soil profile are important considerations. If peat is not present there is effectively no risk of a severe ground fire and using fire in these wetlands may help prevent the formation of organic soil layers (Kirkman et al. 2000). However, accumulated litter, though it is not technically peat can create similar challenges. An alternative method of keeping fires out of wetlands includes using mowed breaks.
2. Burn as often as surrounding communities and in the growing season (every 2-5 years where flatwoods or pine savannah is the surrounding community). The likelihood of Cypress wetlands burning is dependent on the moisture levels in the wetland, which tend to vary seasonally. Dormant season fires, often the norm, coincide with periods when cypress wetlands hold relatively more water, thus are less likely to burn. Conversely, wetlands often experience drawdown in spring, precisely when lightning season fires were historically most common (Kirkman et al. 2000). From an operational standpoint, the precise moisture condition required for fire to carry through these wetlands without igniting accumulated organic matter, are rare and make it challenging for fire managers to provide fire within these communities. This is further complicated because, since fire typically enters these communities from burns in the adjacent uplands, conditions dry enough to burn the cypress communities can be too dry for desirable results from a prescribed burn in adjacent uplands.
3. In cypress wetlands that have been altered through fire suppression or drainage, consideration should be given to reducing fuel loads with dormant season burns before reintroducing growing season fires. The dense shrubby midstory that often surrounds fire-suppressed cypress swamps, including species like titi, fetterbush or gallberry, may not carry a backing fire under weather conditions commonly prescribed for a burn. This effect is more pronounced in the dormant season. If the area is consistently burned with the same wind direction, a pronounced fire shadow may be left even after several prescribed fires. This dense midstory may be top-killed by burning on a variety of wind directions, altering firing techniques (strip head fires, head-firing the swamp from the inside out, etc), by introducing growing season burns, or by mowing. Fire lines, canals, and beds in wetlands or their ecotones should be rehabilitated to restore hydrology and to facilitate fire spread. Where this is not feasible, the firing technique can be altered to carry fire over barriers that prevent fire spread. Fire spread into wetlands may be hindered by the orientation of features such as beds relative to the direction of fire spread (i.e., under wet conditions fires may only spread in the direction of beds unless shrub midstories carry fire).
4. Listed species are known to occur, life histories of known species should be considered when implementing a fire program.