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 significantly less common at the end of the fire-free interval, but this decline was reversed by the 2004 fire. Only Eriocaulon compressum, Dichromena latifolia, Polygala cruciata, and Rhexia lutea declined and remained infrequent after the 2004 fire. A few herbaceous species (e.g., Aristida palustris, Zigadenus glaberrimus, and Carphephorus pseudoliatris) benefited from the fire-free interval. The majority of long-lived species responded with increased flowering after the fire, and in some cases, increased flowering was delayed until the second growing season after fire. We conclude that most species in wet pine savannas can withstand periodic extended intervals between fires, and a few may even benefit from such variability. We suggest that adaptations such as fire-regulated dormancy and plasticity enable most plants in this system to tolerate naturally varying fire frequencies.
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1 October 2007
Responses of Two Frequently-Burned Wet Pine Savannas to an Extended Period Without Fire
Sarah E. Hinman,
J Stephen Brewer
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The Journal of the Torrey Botanical Society
Vol. 134 • No. 4
October 2007
Vol. 134 • No. 4
October 2007
fire-free interval
Pinus palustris
Plant community composition
wet pine savanna