Responses of Two Frequently-Burned Wet Pine Savannas to an Extended Period Without Fire1

Abstract

Abstract Ecosystems that naturally burn at short intervals nonetheless exhibit some variability in fire-return intervals. Prolonged fire suppression and exclusion, however, potentially increase this variability beyond some tolerable threshold. Therefore frequent fires at regular intervals are often argued as necessary to maintain herbaceous plant diversity in pine savannas. We measured plant community composition after eight- and nine-year fire-free intervals, preceded by 15 years of fires every three years, at two wet pine savanna sites (Wolf Branch and Sandy Creek) in southern Mississippi. Species composition was quantified after the frequent-fire period (1997), after eight years without fire at Sandy Creek and nine years without fire at Wolf Branch, and for two seasons after a prescribed burn in 2004 at both sites. Monte Carlo randomization tests revealed significant changes in species composition at both study sites. However, most changes were temporary. Numerous herbaceous species appeared to be sign...