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North Cascades Ecoregion: Biodiversity
Home to lynx and mountain goats, rare alpine daisies and thousand-year old cedars, the North Cascades Ecoregion contains some of the largest expanses of wilderness in the lower forty-eight. LocationThe ecoregion (about 10% of Washington) includes the Cascade Mountains north of Snoqualmie Pass and west of the Cascade crest northward into British Columbia. Only a small part of this ecoregion lies in Washington; in British Columbia, it encompasses all of the mainland coast. In Washington, U.S. Highway 2 and the North Cascades Highway (State Route 20) traverse the ecoregion. It takes in the eastern parts of four counties: Whatcom, Skagit, Snohomish, and King. Although towns such as Gold Bar, Index, Skykomish, Darrington, and Concrete lie in the North Cascades, a combination of natural and cultural factors have prevented much urbanization. Outstanding Biodiversity Features
Landforms
The North Cascades are steep, rugged, glaciated mountains formed by volcanic activity. The highest peaks are volcanoes such as Mt. Baker and Glacier Peak, which rise to more than 10,000 feet. Valleys bottoms go down as low as 500 feet. Glacially carved U-shaped valleys and cirques are prominent features. Many rivers drain the North Cascades and flow toward Puget Sound, including the Skagit, Stillaguamish, Snohomish, and Nooksack. Some drainages have been dammed for hydroelectric power and have created large reservoirs, such as Ross and Baker Lakes ClimateThe North Cascades receive high levels of precipitation, from 60 to 160 inches per year as rain or snow, mostly between October and April. Snow, often 20 feet deep, covers the high elevations many months of the year.The Mt. Baker Ski Area holds the record for the most snowfall ever measured in the United States in a single season. It reported 1,140 inches (95 feet) of snowfall for the 1998-99 snowfall season. At middle elevations snowpacks fluctuate through the winter, while little snow accumulates in the lowest valleys.
VegetationThe vegetation here is highly diverse. At lower elevations, forests of Douglas-fir, western red cedar, and western hemlock intermix with riparian areas that support broadleaf trees such as red alder and big leaf maple. At middle elevations, forests of Pacific silver fir and western hemlock cover the slopes. A mosaic of mountain hemlock, Pacific silver fir, yellow cedar, and subalpine parklands occurs at higher elevations. Avalanche chutes can be lined with Sitka alder or vine maple. Throughout the forests of the North Cascades, natural fires large enough to cause significant tree replacement occur at irregular intervals of 90 to 250 years. Here, as elsewhere in Washington, forest dynamics have changed due to human intervention in the form of fire suppression and logging practices, among others. Above timberline, alpine heaths, meadows, and fellfields are interspersed with barren rock, ice, and snow. WildlifeThe North Cascades are home to many species of animals:
This ecoregion provides important habitat for large mammals such as mountain goats, elk, and black bear. Wide-ranging and rarely seen carnivores, including lynx, gray wolves, grizzly bears, and wolverines, can find a home here because it has experienced less residential development and logging disturbance than other regions of the Cascade Mountains. The North Cascades host a wide variety of breeding birds, including bald eagles, osprey, harlequin ducks, spotted owls, marbled murrelets, and many species of Neotropical migrants, such as Wilson’s warbler, Swainson’s thrush, and rufous hummingbird. People in the North CascadesPeople have inhabited the North Cascades for at least 8,400 years, with some evidence indicating habitation 10,000 years ago. The ancestors of Coast Salish and Interior Salish speaking peoples lived in the area, and archaeological evidence shows that they hunted, gathered, and processed plant foods here. Euro-American settlement within the remote and rugged North Cascades occurred slowly over many years. Access was difficult and the good farmland scarce. In addition, homesteaders may have been discouraged by the lack of surveyed lands and the creation of the Washington Forest Reserve in 1897. The Washington Forest Reserve eventually became Mt. Baker-Snoqualmie National Forest. Much of the North Cascades ecoregion belongs to the public and is administered by the National Park Service, the USDA Forest Service (Mt. Baker-Snoqualmie National Forest), and the Washington Department of Natural Resources. The North Cascades National Park Service Complex is made up of three units managed as one: North Cascades National Park, Ross Lake National Recreation Area, and Lake Chelan National Recreational Area. Over 93% of the park complex is managed as the Stephen T. Mather Wilderness, established by Congress in 1988. Mt. Baker-Snoqualmie National Forest encompasses a large portion of the west side slopes of the North Cascades Ecoregion. About 41% of this National Forest is designated wilderness. The Upper Skagit River Hydroelectric Project, which supplies about 20% of the electrical power used in the city of Seattle, encompasses three dams on the Skagit River. Planning began in 1905, and construction on the dams was finished in 1961. Private land in the ecoregion is a legacy of the 1864 Northern Pacific Land Grant, which bestowed vast amounts of land on the railroad that built a trans-continental link to the Pacific Northwest. Many towns in the region started as places that housed and fed railroad construction workers. The Weyerhaeuser Company moved into the region just over a century ago, through a 900,000-acre land sale by railroad baron James J. Hill to his Minnesota neighbor, timber magnate Frederick Weyerhaeuser. The Plum Creek Timber Company is an independent company but has its origins as the Burlington Northern railroad subsidiary that managed the company's timber holdings from western Montana to the Washington Cascades. The economic base for people in the North Cascades ecoregion is primarily forestry and tourism. Human ImpactThe habitats and ecosystems in the North Cascades ecoregion are largely intact, but a number of human activities pose risks to its biodiversity. These include:
The dominant land uses in the North Cascades—forestry, recreation, and conservation—give us ample opportunity to address these risks and find solutions. Definitions:
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