Influences of wind and snow on northern tree-line environments at Churchill, Manitoba, Canada

Abstract

Wind profiles above the snow surface, snow crystal size and quantity were examined during abrasion experiments with white spruce branchlets. During winter, a large proportion of the snowfall was initially blown off the exposed surfaces of Hudson Bay and the coastal tundra regions, into the woodlands. As the woodlands filled up with snow in mid-winter, the rate of snow accumulation in the forest increased from double to triple the snowfall. Variations in the rate of accumulation occurred with wind speed and direction. During May, snowmelt began on exposed tundra, and occurred about three weeks later in the open forest and was characterized there by less runoff, as the water more readily permeated the thawing peat. The late snow beds are characteristic of the forest-tundra woodlands and were usually gone by mid-July. The woodlands were snow free for 1.5-2 months during the year, while the open forest was snow free for about 3 months and the tundra was largely snow free for 6 months or more. -from Authors