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North Cascades: Status and Threats
> Biodiversity Conservation StatusThe North Cascades ecoregion is one of Washington’s best conserved areas. Steep slopes and inaccessibility have favored the preservation of large areas with close to original vegetation. Less than 2% has been converted to urban or agricultural development. These significant stretches of undeveloped habitat foster connectivity and thus benefit wide-ranging carnivores. Most of the ecoregion is in public ownership. The U.S. Forest Service (Mt. Baker-Snoqualmie National Forest) manages the largest amount of land, followed by the National Park Service (North Cascades National Park), and the Washington Department of Natural Resources. The Mt. Baker-Snoqualmie National Forest is charged with managing its land for multiple uses and benefits, and for the sustained yield of renewable resources such as water, forage, wildlife, wood, and recreation. About 41% of Mt. Baker-Snoqualmie National Forest is managed as wilderness. The North Cascades National Park Service Complex is made up of the Park, Ross Lake National Recreation Area, and the Lake Chelan National Recreation Area in the adjacent East Cascades ecoregion. Most of the Park Complex, over 93%, is managed as the Stephen T. Mather Wilderness, established by Congress in 1988. North Cascades National Park is notable for its large size and strict protection status. Most of the Washington Department of Natural Resource’s lands occur on the western edge of the ecoregion. These lands include state trust lands, which are managed to earn money to help fund school construction or local services, as well as several Natural Areas. The four Natural Area Preserves (NAP) in the North Cascades are: Dailey Prairie NAP, Olivine Bridge NAP, Skagit Bald Eagle NAP, and Snoqualmie Bog NAP. The five Natural Resource Conservation Areas are: Granite Lake, Greider Ridge, Morning Star, Mount Pilchuck, and Mount Si. Habitat OverviewForest habitats. In the North Cascades, forest covers about 75% of the ecoregion, with the majority of forest habitats falling into two broad classifications, Westside Lowland Conifer-Hardwood Forest and Montane Mixed Conifer Forest. Westside Lowlands Conifer-Hardwood Forest, extending up to about an elevation of 2,000 feet, is comprised mostly of stands of Douglas-fir, western red cedar, and western hemlock. Sitka spruce and red alder are also common, and a rich array of shrubs and ferns makes up the understory. Much of this habitat type remains on the western slope of the Cascade Mountains in the North Cascades ecoregion, but most of it has been logged in the last 150 years. Only a small amount remains that is older than 200 years; in this ecoregion, these old-growth stands lie primarily in North Cascades National Park. Old-growth Westside Lowlands Conifer-Hardwood Forest exhibits complexity in its structure, including trees taller than 150 feet, a forest canopy that is multi-layered, dead trees (snags), and large logs on the forest floor. This kind of complexity provides habitat to the northern spotted owl and the marbled murrelet, which are species at risk of extinction. The Westside Lowlands Conifer-Hardwood Forest contains 62 plant associations in the National Vegetation Classification; of these, 17 (27%) are considered globally or critically imperiled. This habitat is one that is considered of highest conservation priority in the Washington Department of Fish & Wildlife’s Comprehensive Wildlife Conservation Strategy. Higher in elevation, about 2000 to 5000 feet, the Montane Mixed Conifer Forest includes mountain hemlock, Pacific silver fir, and yellow cedar, with Douglas-fir occurring in drier sites. Most of the Montane Mixed Conifer Forest in the ecoregion lies in the wilderness areas of Mt. Baker-Snoqualmie National Forest and the North Cascades National Park Complex and is well protected. Subalpine and Alpine Habitats. In the North Cascades, these habitats lie at elevations from about 4,500 up to 9,500 feet. They accumulate deep snow in winter and summers are cool. Subalpine Parkland, at roughly 4,500 to 6,000 feet elevation, includes several different plant associations in parklands (mosaics of treeless openings and small patches of trees) and woodlands or savannahs (stands of scattered trees). Tree species occurring here are subalpine fir, mountain hemlock, Alaska yellow cedar, and near the eastern edge of the ecoregion in Washington, whitebark pine. Wildflower meadows, avalanche chutes of slide alder and false azalea, stands of heather, and shrubby moist thickets are among other plant associations found in this habitat. At-risk animals such as the grizzly bear, the wolverine, and the Nooksack elk herd are closely associated with this habitat. While most of the Subalpine Parkland habitat in the North Cascades ecoregion has protected status, it is vulnerable to degradation from recreational use, invasive species, and climate change. Subalpine Parkland habitat is considered of highest conservation priority in the Washington Department of Fish & Wildlife’s Comprehensive Wildlife Conservation Strategy. Alpine Grasslands and Shrublands occur above treeline, from about 5,000 feet up to 10,000 feet. Blowing snow and ice in winter make life too difficult for tree species to grow higher than the depth of the winter snowpack; tree species growing at high elevations are kept to a shrub form known as krummholz. Plant associations at these elevations include grasslands, sedge turfs, heather shrublands, and fellfields. Alpine areas are popular destinations for hikers and mountaineers, and they are extremely vulnerable to trampling and degradation through overuse. Once plant cover has been removed or damaged at these high elevations, recovery is infinitesimally slow without restoration efforts. Ice and snow persist year round at the highest elevations, and the North Cascades ecoregion contains about 700 glaciers. Wetland and Riparian habitats. Interwoven among the other habitats in the ecoregion are a number of wetland and riparian habitats, including Open Water (lakes, rivers, streams), Herbaceous Wetlands, Westside Riparian Wetlands, and Montane Coniferous Wetlands. While wetland and riparian habitats have a fairly small footprint in the North Cascades ecoregion, they are rich in diversity and abundance of fish and wildlife. This is especially true of Westside Riparian Wetlands, as defined by Johnson and O’Neil (2001), which occur along the rivers and streams that flow west out of the North Cascades. These riparian wetlands encompass several plant communities, including stands of deciduous trees such as red alder, black cottonwood, and big leaf maple. Shrub thickets, made up of willows, Douglas spirea, salmonberry, and red-osier dogwood among others, are another important plant community. Westside Riparian Wetlands provide important fish and wildlife breeding habitat and movement corridors, as well as being important to people for water purification, flood control, recreation, and scenic beauty. These wetlands have been altered by many means; they are considered of highest conservation priority in the Washington Department of Fish & Wildlife’s Comprehensive Wildlife Conservation Strategy. Plants and animals of conservation concern:Both the Washington Natural Heritage Program (WNHP) and the Washington Department of Fish and Wildlife (WDFW) track species that are at-risk in the North Cascades. WNHP has identified and ranked 37 plants and 17 animals as priorities for inclusion in its Natural Areas system. WDFW has identified 28 Species of Greatest Conservation Need. These are classified as Endangered, Threatened, Candidate, or Monitor species, as well as those needing additional research. Globally Rare Plants in the North Cascades Ecoregion
Source: Washington Natural Heritage Plan (Washington Department of Natural Resources) Endangered & Threatened Animals in the North Cascades Ecoregion
Source: Comprehensive Wildlife Conservation Strategy (Washington Department of Fish and Wildlife) ThreatsThe primary threats to biodiversity conservation in the North Cascades ecoregion are habitat loss and degradation, population growth, and climate change. Of these, the most imperative is habitat loss and degradation, especially at lower elevations. Habitat Loss and Degradation. The forests of the North Cascades ecoregion are a rich resource, and forests underpin much of Washington’s identity and economy. Forest management practices on the Mt. Baker-Snoqualmie National Forest and on private forestlands continue to evolve in response to research on methods and productivity and to regulations and incentive programs. Legacies from the region’s history of supplying timber to a wood-hungry nation and world include younger stands, changes in forest dynamics, and landscape alterations.Stands throughout the lower elevations of western Washington, including the North Cascades, have been harvested in the past 100–150 years. Most old-growth forest has been harvested—only about 3% of western Washington forests are presently in this age class. Forest composition and dynamics in the North Cascade have changed in response to several management practices, including clearcut logging, plantation forestry, and fire suppression. Clearcut logging and plantation forestry (primarily of economically choice Douglas-fir) lead to less diverse tree canopies and forest stands. Fire, an occasional but integral part of the ecosystem, was formerly seen as destructive to timber resources. The resulting fire suppression has led to increased fuel loads and risk of catastrophic fires. Management practices are shifting to allow fire a role in the ecosystem. However, a factor that complicates letting natural fires burn is the increasing human population on the wildland interface. Landscape alterations include roads and other transportation corridors and many changes to riparian systems. While parts of the North Cascades ecoregion are remarkable—and nearly inaccessible!—for having no roads, roads do create wildlife barriers and hazards and cause habitat fragmentation. An additional and increasing problem is that roads serve as corridors for invasive species, such as the tansy (Tanacetum vulgare) growing along State Route 20 west of Newhalem. Road building can also cause changes to riparian systems through increased sedimentation and debris torrents. Riparian systems have been altered by forest management practices. These changes include shifting the composition of streamside forests from conifers toward alder and salmonberry, to reducing woody debris in a channel, to altering the hydrology of an area, and others. Much publicized effects of forestry on salmon-bearing waterways are being addressed by the Forests and Fish Law (pdf document), the Salmon Recovery Funding Board, and other initiatives. Population Growth. The second primary threat to the North Cascades ecoregion is population growth. Population growth drives much of the habitat loss and degradation through increased pressure for development (housing, commercial buildings, transportation needs) and increased pressure on the recreational resources of the region (more people hiking, camping, boating, fishing, hunting, etc.). More recreational use also adds to the risk of introducing invasive species deep in the backcountry. For example, infestations of reed canary grass (Phalaris arundinacea) have been found at Ross Lake. These infestations range from individual plants to five-acre patches. Global Warming. The third major threat to biodiversity conservation in the North Cascades ecoregion is global warming, driven by the accumulation of carbon dioxide and other gases. This will drive multiple changes: melting glaciers, a reduced winter snowpack, and altered plant and animal distributions.
> Biodiversity
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