Range Impacts following the Introduction of Caribou on Southampton Island, Northwest Territories, Canada

Abstract

Changes in the vegetation for various range types subjected to grazing by an introduced caribou population in 1967 on Southampton Island, Northwest Territories, were assesed using a series of exclosures (N = 13; 5.5 m × 5.5 m) in 1990 and in 1991. Changes in the vegetation were related to range use and to prevalent snow conditions. The effect of the exclosures on some factors that are known to influence the production of arctic plant communities (snow condition, timing of snow melt, and soil temperature during the growing season) were also tested. Exclosures had little effect on these physical conditions. Associated with the increase in caribou number there has been a reduction in lichen standing crop; the other plant types were not affected. Under the prevailing snow conditions on the island, winter range appears to be restricted mainly to windswept areas which are nearly free of snow. As a result, some of these areas are showing signs of overgrazing and the past projection of caribou carrying capacity may have been too high. With respect to management, a significant increase in the annual hunting quota is recommended.