| Vegetation dynamics after prescribed fire were modeled on three mountains in the George Washington National Forest representing a chronosequence of conditions since burning: pre-burn, and 1, 2 and 12 years post-treatment. Vegetation structure was more affected by environmental and spatial (burn intensity) gradients than by time since burning. Significant fire effects occurred on southwest aspects and upper slopes, especially among the sapling and shrub strata. Pine and oak regeneration abundance was not affected by fire but shade tolerant tree seedlings decreased, and shade intolerant seedlings increased in importance as a result. Percent cover and richness of herbaceous species increased, partly due to the post-fire germination and growth of various forbs and graminoids. Fire did not affect the abundance of exotic invasive species, but its effects on Ailanthus altissima were inconclusive. Low overstory mortality and prolific sprouting of ericaceous shrubs suggests that understory vegetation effects from single burns are temporary. |
