Geomorphological limits to self-organization of alpine forest-tundra ecotone vegetation

Feedback in the establishment of vegetation has been shown to produce spatial patterns that differ from the geomorphological basis for resources. The dynamics of these spatial patterns have been characterized as self-organization because local processes produce them at landscape scales. Geomorphic patterns could, however, enhance or disrupt the processes that lead to patterns and the interpretation of self-organization. A simulation model that showed such indication of self-organization at alpine forest-tundra ecotones is modified to incorporate a geomorphic feature commonly seen in this environment – solifluction steps – as an exogenous condition in the model. Analyses linking spatial patterns and rates of advance of vegetation indicate that such geomorphic patterns do not alter the dynamics of vegetation until the size of the patterns is about double that of the dimension within which endogenous dynamics operate. The sizes of some geomorphic patterns incorporated in the model are probably larger than any realistic solifluction feature at such ecotones in western North America.