RELATIONSHIPS OF VEGETATION, EARTH HUMMOCKS, AND TOPOGRAPHY IN THE HIGH ARCTIC ENVIRONMENT OF CANADA (15th Symposium on Polar Biology)

Relationships of vegetation, earth hummocks, and topography were studied in the high arctic environment of Ellesmere Island, N.W.T., Canada. A belt-transect 2 m wide and 114 m long was established on a south-west facing slope of a small knoll, where well developed earth hummocks were recognized. The belt-transect was sectioned in 2 m × 2 m successive quadrats. For each quadrat, cover degree of individual species and total vegetation was assessed and recorded. After earth hummocks were categorized conveniently into three types according to a degree of being covered by vegetation, the number of earth hummocks in each quadrat was counted for each type. A topographical crosssection along the belt-transect was surveyed, and vegetation and earth hummock characteristics were correlated with topographical position. Well developed earth hummocks were recognized mainly at the base of a leeward slope of the knoll where snow possibly drifted and stayed long enough to protect vegetation and earth hummocks from strong wind, especially in winter. Vegetation, too, developed well in places where earth hummocks developed well; it consisted predominantly of Salix arctica, Saxifraga oppositifolia, Poa abbreviate, Dryas integrifolia, and Pedicularis arctica. Development of the earth hummocks was regarded as a synergistic product of such factors as fine soil material, topography, snow, permafrost, and vegetation. Snow was considered to play a decisive role in developing and maintaining well developed earth hummocks and vegetation by protecting them from adverse wind effects in winter. This is why the majority of the well developed earth hummocks are confined to leeward slope-bases where wind blown snow accumulates and stays relatively long