Moisture Availability and Lichen Growth: The Effects of Snow Cover and Streams on Lichenometric Measurements

Abstract

Prolonged snow cover and streams exert an influence on the growth rates of Rhizocarpon section Rhizocarpon lichen taxa, with considerable implications for lichenometric dating. Thalli are smaller than expected close to snow patches, due to a reduced growing season and ground instability. At some sites, these negative influences may be balanced or outweighed by the effects of increased moisture availability, resulting in increased growth at a particular point. At the site investigated, streams have little effect on Rhizocarpon section Rhizocarpon growth rates. The discrepancy between this and results obtained from other environments may indicate that Storbreen does not represent a particularly moisture-stressed environment for Rhizocarpon lichens.