Vegetation dynamics after a prescribed fire in the southern Appalachians

In April 1995, the USDA Forest Service conducted a prescribed burn along wi th a south-facing slope of southern Appalachian watershed, Nantahala Nation al Forest, western NC. Fire had been excluded for over 70 years and the pur pose of the burn was to create a mosaic of fire intensities to restore a de graded pine/hardwood community and to stimulate forage production and promo te oak regeneration along a hillslope gradient. Permanent plots were sample d at three locations along a gradient from 1500 to 1700 m. Plot locations c orresponded to three community types: mesic, near-riparian cove (low slope) ; dry, mixed-oak (mid slope); and xeric, pine/hardwood (ridge). Before burn ing (1994-1995) and post-burn (summer, 1995 and summer, 1996) vegetation me asurements were used to determine the effects of fire on the mortality and regeneration of overstory trees, understory shrubs, and herbaceous species. After the burn, mortality was highest (31%) at the ridge location, substan tially reducing overstory (from 26.84 pre-bum to 19.05 m(2) ha(-1) post-bur n) and understory shrub (from 6.52 pre-burn to 0.37 m(2) ha(-1) post-bum) b asal area. At the mid-slope position, mortality was only 3%, and no mortali ty occurred at the low slope. Not surprisingly, percent mortality correspon ded to the level of fire intensity. Basal area of Kalmia latifolia, Gayluss acia baccata, and Vaccinium spp. were substantially reduced after the fire, but density increased due to prolific sprouting. The prescribed fire had v arying effects on species richness and diversity across the hillslope gradi ent. On the ridge, diversity was significantly increased in the understory and herb-layer, but decreased in the overstory. On the mid slope, no change was observed in the overstory, but diversity significantly decreased in th e understory. On the low slope, no change was observed in the overstory or understory. (C) 1999 Elsevier Science B.V. All rights reserved.