Effects of prescribed fire on the buried seed bank in mixed-hardwood forests of the southern Appalachian Mountains
This study characterizes the seed bank prior to and immediately following dormant-season prescribed fire in mature, mixed-Quercus spp. (oak) forests in the southern Appalachian Mountains. Thirty samples from the litter/duff (LD) and the top 5 cm of the mineral soil (MS) were collected from five 5-ha burn units (6 plots per experimental unit) before and immediately after low-intensity prescribed fires, where maximum fire temperatures varied from <79 to 316 °C. A split-plot ANOVA and multi-response permutation procedures (MRBP) were utilized to assess the effects of burn treatment (pre- or post-fire) and seed bank layer (LD and MS) on the diversity and density of the buried seed bank. An average of 471 emergents/m2 was observed in the buried seed bank comprising 133 identifiable taxa. No differences in total seed-bank density, Shannon-Weiner’s diversity index (H'), or overall species composition between pre- and post-fire sampling or between the LD and MS layers were observed. Species richness (S) of the seed bank, however, was slightly greater pre-fire than post-fire, regardless of layer. Similarity, as defined by Sørenson’s index, of species common to the seed bank and aboveground forest understory was low, with a slight increase in Sørenson’s index observed during post-fire sampling of the seed bank and aboveground vegetation. Although we observed only negligible effects of a once-applied, low-intensity prescribed fire on the buried seed bank, the effects of a low-intensity prescribed fire management regime—one that involves repeated low intensity burns—on the buried seed bank are unknown and should be a focus of future studies across mixed-oak forests in the eastern US.