Population Dynamics in Response to Fire in Quercus laevis - Pinus palustris Barrens and Related Communities in Southeast Virginia
Permanent plots in the Zuni Pine Barrens (Isle of Wight Co., Virginia) were sampled in order to: quantify plant population dynamics in response to fire, compare these dynamics among different moisture regimes, compare the effect of mechanical understory removal to that of fire on tree seedling and herbaceous dynamics, and determine the effect of dense lichen (Cladonia spp.) coverage on pine seedling establishment and survival. Fire resulted in 40% aboveground mortality in the overstory, 80% in the sapling/large shrub layer, and nearly 100% in the understory, followed by a 3.3 to 10.6 fold increase in understory density. Regeneration was predominantly by vegetative means and shrub species accounted for greater than 90% of the post-fire density and 80% of the increase in density. In the wetter areas, tree and herbaceous species made up a larger percentage of post-fire understory density than was the case in drier areas, and species diversity was greater. In drier areas, the same species which dominated the understory before the fire continued to do so afterward, and these same species increased in number significantly more than other species. In the wetter areas, the majority of pre-fire dominant understory species were no longer important components of the communities after the fire, and these species either failed to increase significantly or even decreased in number. Several species that were not important components of the communities before the fire increased significantly more than others and were among the dominant post-fire understory species. In drier areas, all significant changes in density occurred in the first year following the fire, while in wetter areas, significant changes occurred in the second year as well. Burning differed from mechanical clearing of the understory in that tree seedling species exhibited greater densities and increases in density. Burned areas did not differ from mechanically cleared areas in herbaceous density or dynamics, but differences in herbaceous species composition were noted. Dense lichen patches did not differ from areas devoid of lichens with respect to pine seedling mortality. Pine seedling density, however, was significantly greater in lichen patches.
Cladonia, Zuni Pine Barrens, Longleaf pine, Oak, Fire ecology, Plant populations, Botany, Ecology and Evolutionary Biology, Forest Sciences
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