ScienceDaily (May 3, 2011) — Rock climbers are having a negative impact on rare cliff-dwelling plants, ecologists have found. Writing in the British Ecological Society's Journal of Applied Ecology they say that in areas popular with climbers, conservation management plans should be drawn up so that some cliffs are protected from climbers.
http://www.sciencedaily.com/releases/2011/05/110503203822.htm