A Multivariate Analysis of Forest Communities in the Western Great Smoky Mountains National Park

Abstract

An integrated sequence of multivariate techniques was applied to the vegetation of the western Great Smoky Mountains National Park. Included in the sequence were hierarchial classification, detrended correspondence analysis and multiple discriminant analysis. Based on the importance of landform in previous research, a system of topographical quantification was developed and also used in the classification. Elevation and the topographical index, termed protection, were the most important variables associated with the 12 classified forest types. Drainage area, another topographic measurement, soil p H and water-holding capacity were also significant in the vegetation analysis. Logging and farming disturbances prior to the formation of the national park were probable causal factors for some forest types. INTRODUCTION The Great Smoky Mountains of Tennessee and North Carolina have been a focal point of vegetation analysis since 1930 (Cain, 1930). Because the Smoky Mountains provide elevation-related temperature and precipitation gradients, complex topographical patterns, and a rich woody-species composition, they have been used repeatedly in studies of the relationships of plants to the environment and within communities. Whittaker (1956) identified species associations throughout the Great Smoky Mountains National Park (GRSM) and defined their positions on a moisture complexgradient. H e concluded that the interaction of elevation, topographic shape and slope aspect determined the vegetation present at a given site. Golden (1974, 1981) approached the problem of vegetation distribution in the central G R S M with an integrated sequence of multivariate techniques (cluster analysis and similarity sorting, discriminant analysis, reciprocal averaging, ordination and canonical correlation) using quantitative environmental variables. H e found the overwhelming importance of topography and elevation as described by Whittaker was also indicated by his data and analyses. Soils data collected by Golden (1981) indicated that the p H of the A horizon and the percent clay in the B horizon were also important correlative factors. The major purposes of this paper are (1) to develop a method for quantifying topographic shape in the Smoky Mountains; (2) to provide an integrated multivariate analysis, including the topographic index, of the western Great Smoky Mountains, and (3) to examine stands disturbed by prepark logging and agriculture. Neither Whittaker (1956) nor Golden (1981) satisfactorily quantified topographic shape, which they cited as being important. Whittaker (1956) assigned a sequential order to land shapes and assumed that the order represented moisture characteristics. Golden (1981) measured the position of stands on slopes and the slope aspect but did not include slope shape. We have constructed an index of topographic shape and included it in our vegetation analysis. Most of the study area was on three major topographic features in the western 'Present address: Department of Biological Sciences, University of California, Santa Barbara, CA 93106.