FUZZY SET ORDINATION ALONG AN ELEVATION GRADIENT ON A MOUNTAIN IN VERMONT, USA

Fuzzy set ordination was used to examine relationships between tree sp ecies and site factors on Mt. Ascutney, Vermont, USA. Prism plots were established at four elevations (455, 610, 760 and 915 m) along contou r lines that encircled the mountain. In addition to elevation, which w as the most important factor affecting tree species composition, slope , aspect and exposure to solar radiation all affected composition; how ever, these latter three factors were important only at 455 m. Topogra phic position was important at higher elevations as well. The response s of tree species to any of these factors were highly individualistic. Plots of the upper bounds of relative basal area of each species agai nst the apparent elevation of sites where that species was found were useful in predicting how important an individual species could become over the course of forest succession. For example, northern hardwoods, which comprise the most common forest type of this region, are not ve ry common on this mountain. This approach shows, however, that they ar e currently at levels well below their potential maximum; this is prob ably due to past disturbance.