Plant Population Dynamics in Response to Fire in Longleaf Pine-Turkey Oak Barrens and Adjacent Wetter Communities in Southeast Virginia

Abstract

PLOCHER, A. E. (Department of Biological Sciences, Old Dominion University, Norfolk, VA 23529). Plant population dynamics in response to fire in longleaf pine-turkey oak barrens and adjacent wetter communities in southeast Virginia. J. Torrey Bot. Soc. 126:213-225. 1999.-Permanent plots in the Zuni Pine Barrens (Isle of Wight County, Virginia) were sampled for four years to quantify population dynamics and dominance shifts in response to fire and to compare these effects among different moisture regimes. Fire caused an average 38% aboveground mortality in the overstory, 84% in the sapling/large shrub layer and nearly 100% in the understory, followed by a 3 to 11 fold increase in understory density. Regeneration in this study was predominantly by vegetative means, shrub species accounted for 90% of the postfire density and 80% of the increase in density. In the xeric barrens, Pinus palustris gained dominance of the overstory and sapling layer at the expense of Quercus laevis. In the subxeric barrens Pinus serotina remained dominant throughout the study. The same overstory species (P. serotinaiP. taeda, Acer rubrumiP. serotina) remained dominant throughout the study in wetter forests, but sapling layer pines were eliminated from the sample in the majority of these stands. In both barrens sites, the same species dominated the understory before and after the fire, and these species increased in number significantly more than others. Increases occurred only in the first year after fire. In wetter areas, most prefire dominant understory species were no longer important components of the communities after the fire, and several of these species decreased in number. Most postfire understory dominants were previously inconspicuous or absent from the wetter communities and these species increased significantly more than others. Increases in density in wetter areas occurred in both the first and second year after fire. These areas also had greater increases in species richness. Following fire, the Zuni Pine Barrens overstory was similar to those of southeastern pine barrens, while the understory closely resembled those of New Jersey pine barrens.