The relative influence of microhabitat constraints and rock climbing disturbance to cliff face vegetation communities
This study is the first to determine the relative influence of pre-existing microhabitat conditions vs. direct rock climbing disturbance to the cliff face vegetation communities of the Niagara Escarpment in southern Ontario. Climbed and unclimbed cliff faces were sampled quantitatively for vascular plant, bryophyte and lichen species richness, percent frequency and community composition, microtopographic feature size and frequency, and measures influencing microclimate. Results revealed that certain microhabitat conditions are related to increases in the richness and cover of cliff face vegetation, and that rock climbers select for different microhabitat conditions when establishing climbing routes. No decreases in vascular plant, bryophyte or lichen species richness or cover on climbed cliff faces were attributable to direct climbing disturbance. Pre-existing microhabitat conditions explained greater proportions of variation in vegetation community composition across unclimbed and climbed cliff faces than climbing disturbance. A policy is presented that permits new climbing route establishment with limited impact.