Effects of fuels, weather, and management on fire severity in a southeastern pine savanna

Abstract

Small scale heterogeneity in fire severity is important in pine flatwood communities of southeastern United States. Heterogeneity in fire severity, in turn, is important because if produces heterogeneity of vegetation in these habitats. By measuring fuel scorch and consumption immediately after a fire, I documented small-scale heterogeneity of fire severity. I found that pre-fire fuels and management had significant effects on fire severity, whereas weather did not. Weather, however, demonstrated variation over the 2007 fire season and is clearly a primary driver of fire behavior and effects in natural fire regimes (Johnson 1992). I attribute the lack of weather influence on fire severity to mainly to management practices within the Avon Park Air Force Range. The prescribed fire regime at the APAFR consists of two conflicting goals: 1) ecosystem integrity and 2) control. Fire managers burn particular areas under particular weather conditions to reduce the potential for spotting or jump fires. Additionally, outside agencies with other objectives often dictate when prescribed fires can occur. In particular, state forestry agencies often impose burn bans precisely when natural, lightning initiated fires historically occurred and produced ecologically sound effects. My study suggests that the range of fire severity seen in a natural fire regime is greatly reduced in a prescribed one. This effect may reduce species diversity by reducing opportunities for recruitment, removal of competitive dominants, and encroachment by plants that are not fire tolerable.