Vegetation colonizing the bed of a recently drained thermokarst lake (Illisarvik), Northwest Territories

Abstract

Illisarvik is the site of a thermokarst lake that was artificially drained in August 1978. The lake bed is now dry in most areas and wind erosion is extensive. The surface material is either sandy peat or organic lake mud, except along the eastern margin, where it is sandy. Substrate type appears to have had little influence on distributional patterns of the colonizing vegetation. More important factors are probably erosion, surface wetness, and proximity of the lake-bed margin. Common on the lake bed are Puccinellia borealis and Arctagrostis latifolia. Other widespread species include Senecio congestus, Carex aquatilis, Descurainia sophioides, Matricaria ambigua, Artemisia tilesii, Arctophila fulva, and Stellaria longipes. Senecio and Arctophila form dense stands around the two small residual ponds. Eroded surfaces have a very scant cover of Descurainia seedlings and Puccinellia tussocks. Many elements of Illisarvik's flora are common to other recently disturbed sites near the Arctic coast of northwestern North America.