Rock-weathering by the lichen Lecidea auriculata in an arctic alpine environment

Scanning electron microscopy reveals that Lecidea auriculata penetrates rock surfaces, detaching, incorporating and expelling flakes of rock. Measurements on an age sequence of moraine ridges illustrate changes in the extent and intensity of weathering over time. A minimum rate of surface lowering (0·0012 mm a^?1) is 25 to 50 times faster than weathering due to other processes in the same area. The spatial pattern of weathering is influenced by the narrow ecological range of the species. Surface rocks on dry, exposed sites are probably weathering much more rapidly than those in adjacent damp hollows and beneath snowpatches.