Prescribed fire is an important component of management of southeastern pine savannas. Understanding more about how fire affects their species rich groundcover may lead to better management of this threatened ecosystem. In 2004 we established three 1 m square plots at 20 different sites in a pine savanna that has been undergoing habitat restoration with prescribed fire since 1992. Plots were burned in alternate years, with half (10) of the sites burned each year. All stems growing in the plots were counted and identified to species at the end of the summer growing season. Pine savanna ground cover is dominated by herbaceous species and includes a variety of functional groups such as annuals, perennials, and C4 bunchgrasses. We evaluated how these different groups responded to fire. We considered the effects at two time scales. First, to determine which groups were stimulated or inhibited by fire we compared fire to non-fire years. Second, we evaluated the data for long-term changes over the five years of the study that may be a result of the habitat restoration at the site.
Results/Conclusions
Bunchgrass stem numbers increased through the duration of the study. Thus, although the site had already been undergoing restoration for more than 15 years at the time the study was initiated, there were still ongoing changes in the number of bunchgrass stems. The pattern of long-term increase in stem numbers was not seen in any of the other groups of herbaceous species. Thus pine savannas may continue to change even after many years of habitat restoration with prescribed fire. All groups except bunchgrasses had higher stem numbers in fire years. Although there were increases in fire years for both perennials and annuals, the amount of increase in fire years was greater for annuals than for perennials. Thus, fire increases the presence of annuals, and may facilitate their continued persistence in pine savannas.