Vegetation Succession and Biogeomorphic Interactions in Glacier Forelands

Abstract

Proglacial areas are not only the stage for glacial processes and paraglacial dynamics, which shape the landscape following glacier retreat. At the same time, the new terrain is colonized quickly by plants and animals. Different plant species follow each other in a sequence of successional stages. This sequence is controlled by both abiotic and biotic processes and depends on local-, landscape- and regional-scale environmental factors, such as soil properties, topography and elevation. Yet, successional sequences are often disrupted or changed by disturbances. For example, geomorphic processes delay vegetation succession, limit its development to pioneer stages or change its pathways. However, vegetation succession is not only changed by disturbances, plants can also actively influence geomorphic processes. These biogeomorphic interactions control patterned ground, glaciofluvial floodplain and moraine slope development. Once geomorphic activity decreases to a certain degree, ecosystem engineer species can establish, e.g. the dwarf shrub Dryas octopetala on lateral moraine slopes. When plant biomass reaches a certain volume, it starts to affect geomorphic processes; e.g., interactions change the dominant process on moraine slopes from slope wash and slide to bound solifluction. These biogeomorphic feedbacks stabilize the glacial sediments and facilitate establishment for later successional species, such as trees.