Ecology of the North Cascades

North Cascades
The North Cascades are high and rugged with varied conifer species.
Ecology
Realm	Nearctic
Geography
Country	United States Canada
State	Washington British Columbia

The Ecology of the North Cascades is heavily influenced by the high elevation and rain shadow effects of the mountain range. The North Cascades is a section of the Cascade Range from the South Fork of the Snoqualmie River in Washington, United States, to the confluence of the Thompson and Fraser Rivers in British Columbia, Canada, where the range is officially called the Cascade Mountains but is usually referred to as the Canadian Cascades. The North Cascades Ecoregion is a Level III ecoregion in the Commission for Environmental Cooperation's classification system.^[1]

The terrain of the North Cascades is composed of high, rugged mountains. It contains the greatest concentration of active alpine glaciers in the conterminous United States and has a variety of climatic zones. A dry continental climate occurs in the east and mild, maritime, rainforest conditions are found in the west. It is underlain by sedimentary and metamorphic rock in contrast to the adjoining Cascades which are composed of volcanics.^[2]

The North Cascades has a diversity of plant and animal species.^[3] It contains more than 1630 vascular plant species.^[4] The range has a number of top predators, including bald eagles, wolves, grizzly bears, mountain lions and black bears.^[3] The range is home to at least 75 species of mammals and 200 species of birds that either pass through or use the North Cascades for a breeding area. There are also 11 species of fish on the west side of the Cascades.^[3] Examples of amphibian species occurring in the North Cascades include the western toad (Bufo boreas) and the rough-skinned newt (Taricha granulosa).^[5]

The ecology of the area can be understood by following a west-to-east line at the southern end of the North Cascades, at approximately 47.5 degrees north. As the line passes through the Cascade range, it passes through a number of ecoregions, first getting higher and colder, then getting warmer, yet drier. Each of these component ecoregions can be described by either a tree indicator species, or by a lack of trees: western hemlock, Pacific silver fir, subalpine mountain hemlock, alpine, subalpine fir, and grand fir/Douglas fir.^[6]