The vegetation of the Balsam Mountains of southwest Virginia: A phytosociological study

Abstract

RHEINHARDT, R. D. AND S. A. WARE (Dept. Biol., College of William and Mary, Williamsburg, VA 23185). The Vegetation of the Balsam Mountains of southwest Virginia: a phytosociological study. Bull. Torrey Bot. Club 111: 287-300-1984. A quantitative phytosociological survey was made of the woody and herbaceous vegetation of theBalsam Mountains of southwest Virginia. Sixty-five forest stands were sampled between 1125 and 1547m in elevation. Density measurements for understory vegetation and per cent cover for herbaceous species were measured in 20 of the 65 stands. Stands were ordinated using detrended correspondence analysis (DCA), and divided into nine community-types: spruce, spruce-fir, northern hardwoods (beech-maple and dwarf beech subtypes), yellow birch (ravine and boulder field subtypes), mesophytic, mesophytic-oak, and northern red oak. A correlation analysis was performed to test for significant correlations between community composition and environmental parameters. Canopy species importance values tended to correlate predictably with most environmental parameters (particularly with elevation and moisture, and associated parameters such as pH). Herbaceous vegetation commonly associated with mesic conditions tended to show a strong correlation with magnesium and calcium. The first ordination axis of both the canopy and herbaceous vegetation correlate with an elevation-moisture gradient. Axis 2 of the canopy ordination, which correlates with calcium levels and herbaceous species diversity, separates mesophytic from mesophytic-oak communities. Axis 2 of the herbaceous ordination, which correlates with magnesium levels and organic matter percentage, separates mesophytic, mesophytic-oak, and northern red oak communities. One fairly extensive community-type, located on open north slopes, resembles the high elevation cove forests of the Great Smokies. In fact, the vegetation of all topographic types was found to be much more mesic than forests of similar topography elsewhere in the southern Appalachians. Slopes below 1500 m in elevation may have been dominated by spruce prior to the large scale logging operations of the early 1900's. Perhaps the disturbance of former boreal forests has enabled mesic hardwood forests to exist at these higher elevations where moisture is abundant.