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

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Abstract
Spatial patterns of plant communities near Atkasook (Meade River) on the Gubik Sands of the Alaskan Arctic Costal 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.