The effect of ski trails on the woody plant species composition and structure in adjacent old-growth forests at Wachusett Mountain State Reservation in Princeton and Westminster, Massachusetts

Williams, David K.
Peter Palmiotto, PhD
Department of Environmental Studies
The largest known old-growth forest in Massachusetts is growing on the upper slopes (480 to 600 m above sea level) of Wachusett Mountain in the towns of Princeton and Westminster. Old-growth forest on the north slope or Wachusett Mountain was fragmented by alpine ski trails developed between the 1920’s and the 1980’s. Forest fragmentation has been linked to detrimental forest impacts including the loss of genetic diversity. The extent of change and depth of penetration into adjacent forest varies due to the complex interactions of associated biotic and abiotic factors. The object of this study was to determine if and how maintained ski trails influence the composition and structure of old-growth forest and to determine if ski trails provide access for exotic species to invade old-growth forests. Ski trail impacts were assessed through data collected in a series of 61 forested sample plots established along transects running parallel with topographic contours and perpendicular to ski trails. Sample plots were established at forest edges and at twenty and forty meter distances into forest interiors. Results of this study indicate that forest edges are restructuring with minor changes in the distributions of some naturally occurring species including northern red oak and eastern hemlock. This restructuring is correlated with east and west facing forest edges. Sapling density of northern red oak, eastern hemlock, red maple, yellow birch, striped maple and witch-hazel was significantly different between edge plots and forest interior plots. Red oak densities were generally greatest along forest edges and specifically along edges with eastern exposure. Sapling densities were lower in areas dominated by hemlock. Species richness was also slightly higher in edge plots indicating that edges are restructuring although overall species composition is stable. Dominant species are reproducing and barring any catastrophic impacts, the forest is relatively stable. There were no significant differences detected between the densities of dead trees along forest edges or interiors. The process of edge restructuring or sealing is processing and should be encouraged. Edges that support dense stands of saplings and mature trees help protect interior forest species that may be susceptible to the greater fluctuations in light and humidity associated with forest edges. Special care should be taken not to disturb the process of edge sealing during maintenance of any old-growth forest edges. Ski trail construction and maintenance did not lead to the establishment of invasive woody plants within the old-growth forests in the leased ski are, despite their presence on lower elevation trails. No invasive species were detected in any sample plots. A study of the herbaceous species composition and distribution in the old-growth forest should be undertaken at the earliest opportunity to supplement the base line data collected in this study.