Vegetational Change and Ice-Wedge Polygons Through the Thaw-Lake Cycle, Arctic Alaska

摘要

Britton's thaw-lake cycle hypothesis was examined by sampling vegetation following both artificial and natural lake drainage in the wet coastal tundra of Arctic Alaska. Sizes of clonal colonies of Eriophorum angustifolium and Carex aquatilis were used in an attempt to age older, naturally drained lake basins. Ice-wedges, polygon development, and formation of thaw ponds were studied. Results show that the thaw-lake cycle does exist. The floristic composition of the vegetation through the cycle is predictable. Ice-wedges exist longer than the thaw-lakes and persist beneath them. They reassert themselves after drainage and are important in re-initiating the polygonal, terrestrial part of the cycle. Drained lake basins are very susceptible to thermokarst erosion. Vegetational succession through the thaw-lake cycle is closely attuned to geomorphic changes and therefore is cyclic.