Tundra Vegetational Patterns and Succession in Relation to Microtopography near Atkasook, Alaska

Abstract

Spatial patterns of plant communities near Atkasook (Meade River) on the Gubik Sands of the Alaskan Arctic Coastal Plain reflect microtopographic relief caused by geomorphic processes. Ice-wedge activity, depth of summer thaw, thaw-lake processes, river meandering, and wind erosion and deposition of sands are the principal processes concerned.

Permafrost, precipitation, and stream-cutting transform microtopographic gradients into steep environmental gradients along which vegetation types sort out rather sharply. Due to annual freeze-thaw processes and large seasonal changes in river flow related to ice-melt, environmental gradients change temporally and spatially in a predictable manner. These changes cause a series of environment-community changes (succession) that can be related to soil-moisture gradients and to disturbance.

No one successional sequence is characteristic of this area, and successional pathways do not converge upon a single vegetational type. Distinct, relatively stable communities, such as tussock tundra or lichen and dwarf evergreen shrub communities, result from different successional sequences in various segments of a microtopographic-moisture gradient. In this arctic region, geomorphic processes and permafrost appear to bestow a long-term cyclic nature to succession.