IMPACTS OF TRAILS ON CLIFF EDGE FOREST STRUCTURE

Plant community structure and soil characteristics were quantitatively studied along forested cliff edges of the Niagara Escarpment in south ern Ontario, Canada. The objective of the study was to try to differen tiate between the effects of two gradients on vegetation structure: th e environmental gradient between the cliff edge and dense forest, and an anthropogenic gradient, generated by the presence of major hiking t rails parallel to the cliff edges. Species frequencies were determined along 69 transects distributed over eight sites with different amount s of past and present trampling disturbance. The data were analyzed us ing cluster and ordination analysis as well as analyses of variance. T he results showed that soil characteristics were the major influence o rganizing the vegetation of cliff-edge forests and that soil propertie s and plant community structure were more strongly influenced by anthr opogenic factors than by the environmental gradient between cliff edge and forest. Trampled plots had some properties in common with cliff-e dge plots. Species richness was highest at intermediate trail-use leve ls; abandonment of heavily disturbed trails resulted in the restoratio n of species richness, but most new colonizing plants were disturbance -tolerant ruderals. Soil properties did not completely recover even af ter 10 years of trail abandonment. The results suggest that the curren t use of cliff edges along the Niagara Escarpment is nonsustainable, a nd reversing its effects on cliff-edge forest structure may take a con siderable amount of time.