Vegetation as an Ecological Indicator of Surface Instability in Rock Glaciers
Nicoletta Cannone, Renato Gerdol
We studied relationships between vegetation, substrate texture, and surface movement velocity in two active rock glaciers in the Central Alps (northern Italy). We also compared the vegetation on the two active rock glaciers with that of adjacent stable areas and with that of an inactive rock glacier. The vegetation patterns on the two active rock glaciers differed sharply from those on the stable areas nearby and on the inactive rock glacier with respect to both total plant cover and floristic composition. Surface movement on the two active rock glaciers ranged from 0-5 to 35-40 cm yr-1 and was largely independent of slope inclination. The most unstable sites were almost free of mosses and lichens and were characterized by vascular species tolerating surface instability in virtue of varying morphological adaptations. However, the distributional pattern of vascular species could not be directly related to surface instability but depended on a combination of substrate texture and movement intensity.