Master of Science Thesis submitted 1996

Effects of Clearcutting and Selective Harvesting on Hardwood Forest Understories in the Southeastern United States

Mary Margaret McKinney


Abstract

The effects of clearcutting and partial timber harvesting on the understories of three southeastern hardwood communities (coastal plain, southern piedmont, and Appalachian mountains) were examined. Vegetation data were gathered the summer before harvest and the summer following harvest. Soil disturbance and percentage slash cover were determined following harvest. Multiple response permutation procedures were used to test the hypothesis that there were no differences in understory species compositions between treatments. Detrended correspondence analyses were used to explore the relationships between community composition and environmental factors. Herbaceous species increased in average percentage cover following harvest. Results suggest that a harvest of greater than 12% of the basal area may be required to achieve this increase, and that a harvest of greater than 33% of the basal area does not result in greater increases. Treatments with similar residual basal areas had similar understory plant compositions, and this appeared to be associated with the distributions of the most abundant species. Residual basal area accounted for approximately 25% of the compositional variance at the coastal plain site and midstory cover accounted for approximately 33% of the compositional variance at the Piedmont site.