At the Tree Line
Travel north from almost anywhere in North America and you'll come to a place where, due to increasingly severe weather and unsuitable soil conditions, trees stop growing and low-lying bushes and other plants take over. Nearly one quarter the length of this "tree line" is encompassed by the Northern Canadian Shield Taiga ecoregion. The ecoregion is a transition zone between the boreal forests and the tundra, supporting both woodland and barren-ground caribou. Also it is perhaps the place in northwestern Canada most frequented by caribou during the winter. It is common for wolves to make their homes, or dens, along the tree line.
Large rock outcrops are common features of this ecoregion. Small lakes and streams feed into the Great Slave Lake. Some of the streams follow eskers, the gravelly remnants of streams that formed under melting glaciers.
Mosses, lichens, cottongrass, and very short dwarf birches cover the ground of this ecoregion, providing food for herbivores such as moose, barren-ground caribou, muskrats, and snowshoe hares. A variety of trees are supported within the ecoregion, including black spruce, white spruce, tamarack, quaking aspen, balsam poplar, and balsam fir. Wolverines, weasels, mink, otters, grizzlies and black bears call the ecoregion home, as do several species of birds, including willow and rock ptarmigans, ravens, and spruce grouse.
Cause for Concern
An estimated 90 to 95 percent of the habitat in this ecoregion remains intact. Mining and mineral exploration, particularly for uranium, diamonds, nickel, and copper, are the most widespread forms of habitat disturbance and are growing rapidly in the western half of the ecoregion. Caribou hunting is poorly monitored and has the potential to impact the population if excessive. Hydroelectric development poses an additional threat, as does urban development along the north shore of the Great Slave Lake.
For more information on this ecoregion, go to the World Wildlife Fund Scientific Report.All text by World Wildlife Fund © 2001