Plant colonization and geodynamics of slopes in a polar oceanic environment (Svalbard,79° N)

Abstract

Investigations of plant colonization patterns and lichenometry have provided new insights regarding past and present slope processes on Svalbard. Major stages in slope evolution during the Holocene have been identified, and the Neoglacial period (3500–2000 B.P.) is suggested as the starting point for the formation of lobate rock glaciers. Estimates of the frequency of episodic meteorological events, which have geo‐morphological implications, indicate a recurrence interval of rainstorm‐triggered debris flows and slush avalanches of 70 to 600 years. Active and stable slope deposits have been distinguished and the importance of runoff during spring melt and subsurface percolation later in the summer is implied. In order to interpret the data it is necessary to take into account lithology and to realize that some plant communities provide better indications than others. In contrast with the great variability of phanerogamic and moss communities, which primarily reflect ecological conditions, the stability of lichens, especially Rhizocarpon geographicum colonizing acidic boulders permits chronological reconstructions back to 4000 B.P. and sometimes even earlier.