Productivity and Carrying Capacity of a Subarctic Sheep Winter Range
DOI:
https://doi.org/10.14430/arctic2179Keywords:
Alpine tundra ecology, Animal ecology, Animal population, Mountain sheep, Primary production (Biology), Tundra ecology, Winter ecology, Aspect, Kluane National Park, Yukon, Sheep Mountain (61 03 N, 138 35 W)Abstract
Estimates of range composition and net primary productivity for a 10-year period are presented for the semi-arid grasslands of Sheep Mountain, Kluane National Park, Yukon, the winter range of a Dall's sheep (Ovis dalli dalli) population. Estimates varied among plots, depending on altitude and aspect, as well as among years, according to rainfall during the growing season. Extremes were 29.1 g/sq m and 120.1 g/sq m. Over the 10-year assessment period, the vegetative composition did not change nor was there a grazing-related reduction in productivity. Winter range use by about 200 sheep was within the carrying capacity of the range. A 40% utilization rate of the winter range forage can evidently be sustained and provides a stocking rate of about 1.9 sheep-months/ha. A significant correlation is demonstrated between forage production of the winter range, lamb survival the following winter, and lamb production the following spring. This correlation indicates that a form of self-regulation of the sheep population is functioning.
Key words: productivity of subarctic, semi-arid grasslands; Dall's sheep, carrying capacity, Kluane National Park, Yukon
