Northern Cascade Ecology

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The Northern Cascade Range with its high, rugged peaks and a variety of coniferous forests

The ecology of the Northern Cascade Range is strongly influenced by the altitude and the rain shadow effects of the mountain range. The Northern Cascades are a section of the cascade chain from the South Fork Snoqualmie River in Washington State to the confluence of the Thompson River with the Fraser River in the Canadian province of British Columbia , where the chain is officially called the Cascade Mountains, but is usually referred to as the Canadian Cascades . The North Cascades Ecoregion is a level III ecoregion on the list of ecoregions in North America (CEC) in the classification system of the Commission for Environmental Cooperation .

The terrain of the North Cascades is characterized by the high, rugged mountains. It contains the highest concentration of active alpine glaciers in the Continental United States and encompasses a variety of climatic zones. There is a dry continental climate in the east and a mild maritime climate with ideal conditions for rainforests in the west. The subsurface consists of sedimentary and metamorphic rocks in contrast to the rest of the cascades, which consist of volcanoes.

Various animal and plant species can be found in the North Cascades. There are more than 1,630 species of vascular plants . Several top predators live in the mountains, such as bald eagles , wolves , grizzly bears , pumas and black bears . In the North Cascades, at least 75 species of mammals and 200 species of birds have been recorded that either cross the North Cascades or breed here. There are also 11 species of fish on the west side of the cascades. Examples of occurring here amphibian species are the Polar toad ( Bufo boreas ) and the Rauhäutige yellow-bellied newt ( Taricha granulosa ).

The ecological conditions of the area can be understood by following a west-east line at the southern end of the North Cascades, about 47.5 ° north latitude. When this line crosses the Cascade Range, it crosses a series of ecoregions; at first it gets colder with increasing altitude, then warmer and finally drier. Each of these ecoregions can either be described by a tree as an indicator species or by the absence of trees: West American hemlock , purple fir , subalpine mountain hemlock , alpine mats (without trees), rocky mountain fir and the common occurrence of coastal fir and Douglas fir .

West American hemlock ecoregion

Coal Creek Falls and surrounding dense vegetation in Cougar Mountain Regional Wildland Park .

The West American hemlock ecoregion nestles in the lower western regions of the North Cascades. The West American hemlock is found at altitudes from sea level to 2,500 ft (762 m). In the Alpine Lakes Wilderness , this ecoregion can be found in the lower elevations around 300 ... 600 m. The mean annual temperature is 47 ° F (8.3 ° C) and the mean annual precipitation 700… 3,000 mm. This region is characterized by dense populations of West American hemlocks , common Douglas fir , giant arborvitae and red alder . The undergrowth is primarily made up of Shallon shamrock , hazel , magnificent raspberry , Igelkraftwurz and common Oregon grape . The West American hemlock ( Tsuga heterophylla ) is an extremely shade-tolerant tree and its young plants are usually found in the undergrowth on the forest floor. She prefers humid, temperate conditions. Where the conditions are drier and colder, they do not get along so well. Western hemlocks can reach heights of over 200 ft (61 m) and diameters of 0.9 ... 1.2 meters. They can be easily recognized by the overhanging tree top. It is not uncommon to see the trees growing in a row on a fallen log. The West American hemlock ecoregion is home to a number of animal species. Black- tailed deer graze in the understory. Foxes, coyotes, pumas and a number of herbivorous mammals can also be found in these lowland forests.

Ecoregion of the purple fir

The circular back wall of Lake Twenty-two at 2,400 ft (732 m) altitude

The forests of the middle altitudes in the North Cascades (600… 1,300 m) belong to the ecoregion of the purple fir. This region makes up the majority of the valleys in the Alpine Lakes area. The mean annual temperature in this ecoregion is 42 ° F (6 ° C) and the mean annual precipitation is between 2,200 and 2,800 millimeters. Typical montane forests in the region are dominated by purple firs , but also contain noble fir , common Douglas fir and Nootka cypress . Deadwood is very characteristic of the purple fir region; this provides small habitats for many plants and animals. The purple fir region is found in the steepest areas of the North Cascades; heavy snowfalls lead to avalanche gullies . In every major catchment area on the western slopes of the Cascades, there is evidence that avalanches cut aisles in the wooded areas in the form of unforested areas. These gullies leave behind succession areas that will develop again towards the forest. Because of the dense forests, the purple fir regions were the preferred area for commercial deforestation before being designated as wilderness areas.

The purple fir ( Abies amabilis ) is extremely tolerant of shade and does not grow well in dry or warmer conditions. It can grow up to 180 ft (55 m) high and reach 0.9 ... 1.5 m in diameter. The plant communities of the undergrowth vary depending on the available moisture. Common shrubs of the understory are grape-leaf maple , shallon shamrock , common oregon , American blueberries ( Vaccinium sect. Cyanococcus ), huckleberry , Igelkraftwurz and rhododendrons . Herb-like plants in the undergrowth that are widespread are beargrass , moss bells , umbel winter love , Canadian dogwood , blue lilies, California blackberries ( Rubus ursinus ), star-shaped fragrance seals , foam blossoms , forest lilies , oak ferns and lady ferns . The microclimate is regulated by the treetops and results in cooler and wetter conditions in summer while it is warmer in winter. The saplings of the purple fir are often found under trees of the same species or under the canopy of mixed forests. Along streams, the clearings in this ecoregion of gray alder , willow and vine leaf maple and herbs such as saxifrage , fireweed , Mimulus ( spec Erythranthe. ) And Bluebells ( Mertensia spec.) Settled. Gray alder and grape-leaf maple can also be found on lake shores and in areas with flat or moderate slopes, as well as swamps and marshes. Examples of purple fir forests can be found in the Commonwealth Basin and the Snow Lake area in the Alpine Lakes Wilderness.

Subalpine ecoregion of the mountain hemlock

Mountain hemlock and subalpine fir forest around Rachel Lake at 4,640 ft (1,414 m) altitude

From the purple fir region upwards it goes over between 4,000 ft (approx. 1,200 m) and 5,400 ft (approx. 1,600 m) altitude into the subalpine ecoregion of the mountain hemlock. This region has a lower mean annual temperature of 39 ° F (3.9 ° C) with mean annual rainfall between 1,600 and 2,800 mm. The ecoregion consists of mountain hemlock forests, subalpine meadows, streams, lakes, wetlands and avalanche runways that create various patterns of succession areas. In the lower areas of this ecoregion there are closed forests, while the higher areas are characterized by a mosaic of meadows and mountain hemlock forests. The mountain hemlock forests consist of the main tree species mountain hemlock ( Tsuga mertensiana ), rock mountain fir , Nootka cypress and purple fir . Washington's alpine and sub-alpine areas make up about 4.4% of the total land area.

With increasing altitude, the mountain hemlock becomes the dominant species, although co-dominance with Nootka false cypresses and purple firs can also occur. Mountain hemlocks can be considered to be up to 1,000 years old; they live longer than purple firs. Trees between 500 and 700 years old can be 100 ft (30 m) to 125 ft (38 m) tall. The cones can be 5 ... 7.5 cm long and develop at the ends of the branches. These conifers are easy to distinguish from the others because of their dense gray-green needles. According to Franklin and Dyrness, the understory of co-dominant mountain hemlocks and purple firs consists mainly of large huckleberries ; where the Nootka false cypress co-dominates, the understory consists of dense collections of rhododendrons , huckleberries and whitebeams ( Sorbus spec.).

At the upper limits of the subalpine ecosystem, where the abiotic conditions tend to lead to stress for the plants, the trees grow patchy clumped together. Trees from this area can be recognized by their curved wood shape. Trees at these high altitudes take on a flag-like shape ("wind flies"), with the branches pointing to one side showing the prevailing wind direction. The height of the crown where no branches can grow is determined by the depth of the snow. There are several reasons trees take these shapes. Strong winds, which carry ice particles with them, sand the layers of wax on the needles on one side of the trees and damage the growth of the branches. In addition, the wind creates a drying effect in the needles, so that they die on one side.

Penstemon davidsonii in Mount Pilchuck State Park at 5,300 ft (1,615 m) elevation.

Interspersed in the island-like patches of forest are park-like areas with magnificent meadows in the higher areas. Events such as fire, avalanches, small-scale snow movements and climate change make the boundaries of these areas and the balance of trees and meadows dynamic. The forest islands typically consist of mountain hemlocks, purple firs, and Nootka false cypresses. There is often an invasion of trees in the meadow patches; this was the case in the 1930s due to significant warming. Such invasions also occur with disturbances.

The beautiful meadows are very popular with hikers. Wild flowers from this ecoregion are Lilium columbianum (English "tiger lily"), large-flowered dog's tooth , Clintonia (English "bead lily"), Clintonia uniflora (English "queen's cup"), columbines ( Aquilegia spec.), Asters , forest lilies ( Trillium spec.), Everlasting (English "pearly everlasting"; Anaphalis ), real valerian , Ipomopsis aggregata (English "skyrocket"), flowers of gods (English "shooting star"), beard thread , lice herbs , Gentiana calycosa (engl. "mountain bog gentian") Mimulus (engl monkey flower;. Erythranthe spec). Eisenhut , blue bell (eng "blue bell";. Mertensia spec). bellflowers , heart flowers , Lewisiopsis tweedyi (eng "Tweedy's lewisia"). balsamorhiza , wild orchids and others. The main flowering time of these flowers, which can be found in meadows and along the streams, is from mid-July to mid-August. The park-like areas of the mountain hemlock ecoregion are clearly delimited by different climatic and topographical conditions.

The two dominant types of vegetation in this mountain region - forests and meadows - have very different microclimates . The amount of global and UV radiation can vary considerably depending on the time of day, the slope, the season, the degree of coverage and the type of vegetation. The temperatures adjust depending on these conditions. Compared to the hemlock forests, the park-like areas show greater temperature fluctuations. These can be up to 28 K in the park-like areas, while the fluctuations in the forests rarely exceed 10 K. This is due to the canopy, which creates more sheltered conditions than are available on the open areas of the meadows. In addition, the soil temperature has a direct influence on the biological activity of soil organisms and root systems. Daily and seasonal changes in temperatures have an enormous influence on the heat dissipation and absorption of the soil. However, the snow cover occasionally acts as a buffer against temperature changes in the soil. The mountain hemlock forests are the wettest and coldest forests in the wooded areas of the Cascades.

When wealth of this region many species migrate through at least one season, so Mountain Goat , Scharzwedelhirsch , American Black Bear , Elk , Puma and many bird species. Only the whistling ice gray marmot is restricted to the subalpine and alpine zones. In addition to the variety of mammals, there is a variety of insect species that are linked to the occurrence of flowering plants. Other important pollinators in this area are hummingbirds . There is still much to be researched and discovered in order to understand the interactions and dependencies of the species in both the alpine and subalpine ecosystems.

Alpine ecoregion

Mount Daniel , looking up from 6,100 ft (1,900 m)

The Alpine ecoregion makes up a large part of the North Cascades. Alpine areas like this are rugged with rocky ridges, snow fields and partially vegetation-covered terrain; they are above the tree line . The tree line in the Alpine Lakes Wilderness is about 6,000 ft (approx. 1,800 m). The mean annual temperature is 37.5 ° F (3.1 ° C), the mean annual precipitation is only 460 mm. These conditions, together with the prevailing winds and the ice they contain, are not conducive to the growth of trees. Due to the extreme temperatures and the low rainfall, there are only a few plants in the ecosystems compared to the lower elevations that are also more simply structured. However, precipitation or its lack is a more limiting factor than temperature. Both plant and animal species have adapted to these difficult environmental conditions in a variety of ways.

The high-altitude habitats with strong winds, long-lasting snow cover, steep terrain, large temperature fluctuations and intensive UV radiation lead to special adaptations of the species. Alpine regions generally have low-oxygen conditions, which lead to increased energy expenditure by the organisms living there. The breeding times of the animals are shorter in the higher areas. In addition to the shorter breeding seasons, survival requires seasonal migrations to the adequate habitats in terms of nutrition and other living conditions. However, species such as the white-tailed ptarmigan , the ice-gray marmot and the whistling hare stay in the high elevations of the cascades all year round and only leave them to look for spots with sparse vegetation. The majority of species migrate to deeper regions at certain times throughout their life. Adaptations such as the torpor of the hummingbirds, the camouflage colors of mountain goats and coyotes, the build-up of fat reserves and the ability of birds of prey to move efficiently despite the strong winds are just a few of the ways species can cope with alpine conditions. The white-tailed ptarmigan adapts perfectly to the seasons with its change of plumage from a completely white bird in winter to a brown bird in summer. Many species have fewer juveniles in the higher areas than in the lower areas, but spend more time rearing these few.

A white-tailed ptarmigan merges with the alpine tundra east of Glacier Peak .

While alpine ecosystems offer difficult environmental conditions for the species, there are also advantages for animals to colonize these areas. In winter, when the snow cover is closed, the strong winds bring plant sprouts and seeds to the surface, which can be eaten by the animals. In spring, insects are blown from the low-lying areas onto the snowfields and are available as food for the birds and mammals of the Alpine region. When the snow melts, a gradient is created that gradually lets the plants emerge and provides herbivores with new food along this gradient. Spring food availability is considered to be the limiting factor for the reproduction of a number of species such as the mountain goat. The leaves and fruiting in late summer beyond the snowfield borders also provide a source of food for animals that are dependent on these areas. Black bears , songbirds and marmots in the North Cascades and the Alpine Lakes Wilderness find cover in the lush vegetation of the avalanche gullies that descend into the subalpine forests. There appears to be a lower rate of infection and parasitization in the higher elevations, which gives the animals another benefit. The alpine grouse provide an example of alpine animals that have fewer infections and intestinal parasites. Other animal species migrate to the higher elevations in the summer months to avoid the insects and look for food in the meadows.

Rock Mountain Fir Ecoregion

Patchy forest with rock fir, mountain hemlock, and rock larch at 6,200 ft (approx. 1,900 m) in the Wenatchee Mountains .

The ecoregion of the rock mountain fir , which extends down to the lowlands on the east side of the cascade chain, is found at altitudes of 4,200 ft (approx. 1,300 m) to 6,000 ft (approx. 1,800 m). This region has the same mean annual temperature as that of the mountain hemlock, namely 39 ° F (3.9 ° C), but a significantly lower annual precipitation of between 1,000 and 1,500 millimeters, with much more snow than rain falling. The ecosystem of this region includes rock mountain fir forests, subalpine meadows, avalanche gullies as well as wetlands, streams and lakes.

The rocky mountain fir forests in the North Cascades provide habitats for common Douglas fir, Engelmann spruce , rocky mountain larch and white-stemmed pine . The Engelmann spruce and the rock mountain fir usually occur together. In the high altitudes of this ecoregion, the rocky mountain fir takes on the shape of a Krummholz. The region of the rock mountain fir is characterized by patches of forest and meadows, which act in the high elevations as in the ecoregion of the mountain hemlock.

Coastal Fir Ecoregion / Common Douglas Fir

Common Douglas fir at 4,965 ft (1,513 m) in the Wenatchee Mountains

On the east side of the cascade chain, the coastal fir / common Douglas fir ecoregion forms highly diverse forests; they have the highest tree diversity among the forested ecoregions in Washington. In addition to coastal fir and common Douglas fir, the tree species represented there also include Engelmann spruce , rock mountain fir , yellow pine , coastal pine , western Weymouth pine , white-stemmed pine , western American larch and rock mountain larch . This ecoregion is characterized by an average annual temperature of 46 ° F (7.8 ° C) and an average annual precipitation of 600… 1,100 mm. The ecoregion is found at altitudes between 2,000 ft (approx. 600 m) and 5,000 ft (approx. 1,500 m).

In the higher areas of this ecoregion, mountain hemlock and rocky mountain fir are the dominant species, while coastal fir and common Douglas fir are in the lower areas. There is variability in the vegetation of the understory; The species found in this ecoregion include Calamagrostis rubescens , Carex geyeri ("elk sedge"), other sour grasses , low shrubs, vine-leaf maple , white alder and huckleberry ( Vaccinium spec. and Gaylussacia spec.). The heterogeneous landscape offers habitats for many animal species, including grazers such as deer and elk , as well as black bears , many herbivores and a variety of birds.

fauna

A wide variety of reptiles , amphibians , mammals , birds and arthropods can be found in the North Cascades. A few grizzly bears ( Ursus arctos horribilis ) inhabit the northernmost cascades near the border between Canada and the United States . A pack of wolves with cubs was detected in Okanogan County in 2008 , the first such pack in Washington since the 1930s. Other predators include cougars , American black bears , fishing marten, and wolverines .

There are more than 75 species of mammals in the cascades, including the mountain goat that lives in the high alpine tundra. Bird species include the bald eagle , osprey, and collar duck . Examples of occurring in the North Cascades amphibians are the Polar toad ( Bufo boreas ) and the Rauhäutige yellow-bellied newt ( Taricha granulosa ). What is unusual for the newt population is that an estimated 90 percent of the adult animals are perennibranchiate .

See also

Commons : Category: Canadian Cascades  - Album with pictures, videos and audio files
Commons : Category: North Cascades  - Album with pictures, videos and audio files

Individual evidence

  1. ^ Ecological Regions of North America, Levels I-III . Commission for Environmental Cooperation. Retrieved April 6, 2009.
  2. Level III ecoregions . In: Western Ecology Division . US Environmental Protection Agency. Retrieved March 11, 2009.
  3. a b c d e Karen Kefauver: North Cascades National Park: Wildlife . In: GORP . Orbitz. September 15, 2010. Archived from the original on June 7, 2012. Retrieved June 6, 2012.
  4. Plants . In: North Cascades National Park . National Park Service. May 16, 2012. Retrieved June 6, 2012.
  5. a b Ashley K. Rawhouser, Ronald E. Holmes, Reed S. glesne: A Survey of Stream Amphibian Species Composition and Distribution in the North Cascades National Park Service Complex, Washington State . 2009. Archived from the original on June 7, 2012. Retrieved June 7, 2012.
  6. a b c d e f g h i j k l m n o p q r s t Arthur Kruckeberg: The Natural History of Puget Sound Country . University of Washington Press, 1991, ISBN 0-295-97477-X .
  7. a b c d e f g h i Alpine Lakes Area Land Management Plan . USDA Forest Service, 1981.
  8. a b c d e f g W. Gold: BIS258 lecture notes . University of Washington. January 28, 2008. Retrieved March 15, 2009.
  9. a b Pacific Silver Fir . Washington Department of Natural Resources. Archived from the original on May 5, 2011. Retrieved March 11, 2009.
  10. a b c d e f D.H. Johnson, TA O'Neil: Wildlife Habitat Relationships Washington and Oregon . Oregon State University Press, Oregon 2001, ISBN 0-87071-488-0 .
  11. ^ A b Jeff Smoot: Backpacking Washington's Alpine Lakes Wilderness . The Globe Pequot Press, Helena, Montana 2004, ISBN 0-7627-3098-6 .
  12. Grizzly Bears In the USA and the North Cascades: Past and Present . Grizzly Bear Outreach Project. Archived from the original on January 8, 2008. Retrieved August 24, 2009.
  13. ^ Gray Wolf Conservation and Management . Washington Department of Fish & Wildlife. Retrieved May 8, 2011.
  14. ^ A b Animals . In: North Cascades National Park . National Park Service. Retrieved June 6, 2012.
  15. C. Michael Hogan: Rough-skinned Newt (Taricha granulosa) . In: Globaltwitcher . 2008. Archived from the original on May 27, 2009. Info: The archive link was automatically inserted and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved May 21, 2009. @1@ 2Template: Webachiv / IABot / www.globaltwitcher.com