Early Vegetative Response to Wildfire in a Table Mountain-Pitch Pine Forest

Abstract

Abstract. This study was established to measure vegetation in a mid-elevation Pinus pungens Larnb.- Pinus rigida Mill. (table mountain pine-pitch pine) forest following wildfire in the Shenandoah National Park, Virginia. Vegetation in the overstory, shrub, and regeneration strata were monitored one and two growing seasons following a July, 1988 wildfire. High severity burn areas were impacted greater in terms of stand composition, structure, and diversity than areas of low severity. Two years after fire occurrence, overstory basal area mortality was nearly 98 percent in areas of high severity, and only 26 percent in areas of low severity. The live, residual overstory basal area in the areas of low fire severity did not differ significantly from adjacent unburned areas until the second year due to delayed mortality following fire injury. Wildfire resulted in the mortality of nearly all shrub stratum species; however, the most significant changes in species importance values and diversity were detected in high severity areas. Unlike the overstory and shrub strata, species diversity of the regeneration stratum increased following wildfire. This increase was attributed to the invasion of early colonizer species and the germination of Pinus pungens and Pinus rigida seedlings following fire. Although changes or shifts in species importance and diversity occurred in the overstory and shrub strata, these shifts are likely temporary as stems from previous species grow into these size classes. The exclusion of fire from Pinus pungens-Pinus rigida pine forests may be a greater cause for concern than fire occurrence.