The Importance of Disturbance versus Physiography in Defining Vegetation Composition and Predicting Possible Successional Trajectories

Abstract

ABSTRACT Regional (climate/soils) and local (aspect) physiography determine plant community composition. However, changes in initial floristic composition after a disturbance may be severe enough to alter the successional trajectory predicted by physiography. We addressed the question of which is more important, disturbance or physiography, in determining vegetation composition and the consequent successional trajectory. We evaluated understory vegetation of forest communities exposed to four disturbance types (control, single burn, diameter-limit cut, and first-removal shelterwood) 2–5 yr postdisturbance. Study sites were located within each disturbance type on northeast and southwest aspects within the Appalachian Plateau and the Ridge and Valley provinces. Vegetation composition was analyzed with nonmetric-multidimensional scaling, two-way nonparametric multivariate ANOVA, and indicator species analysis. The relationship between disturbance and key environmental variables, including canopy opening and ...