The Ecology of the North Cascades is heavily influenced by the high elevation and rain shadow effects of the mountain range.

[3] Examples of amphibian species occurring in the North Cascades include the western toad (Bufo boreas) and the rough-skinned newt (Taricha granulosa).

[6] In the Alpine Lakes Wilderness this ecoregion can be found in the lower elevations around 1,000 to 2,000 feet (300 to 600 m)[7] The average annual temperature is 47 °F (8 °C) and it gets between 70 and 300 centimetres (30 and 120 in) in precipitation per year.

[7] The western hemlock (Tsuga heterophylla) is an extremely shade tolerant tree and it is common to find its seedlings and saplings in the understories of the forest floors.

[6] Fox, coyotes, cougars, and an assortment of herbivore mammals and birds can also be found in these low elevation forests.

The Pacific silver fir zone is in some of the steepest parts of the topography and heavy snow often leads to avalanche gullies.

The Pacific silver fir (Abies amabilis) is extremely tolerant of shade and does not fare as well in drought or warmer temperatures.

[6] The microclimate of the understory is moderated by the forest canopy causing the conditions to be cooler and moister in the summer and warmer in the winter.

[6] Along streams in this ecoregion, breaks in the forest are replaced by mountain alder, willow and vine maple and herbs such as saxifrage, yellow willow-herb, monkey flowers, and bluebells can be found.

[6] Mountain alder and vine maple can also be found around lake edges and in areas of flat or gentle slopes, bogs, or marsh habitat.

[8] This ecoregion consists of mountain hemlock forests, subalpine meadows, streams, lakes, wetlands and avalanche gullies creating distinct patterns of new succession.

Trees of this upper boundary will take on a flag appearance with branches extending from one side indicating the prevailing wind directions.

Strong winds combined with ice particles will cause abrasion scouring the waxy cuticle from one side of the tree creating damage that will prevent branch formation and growth.

Events such as fire, avalanches, snow slumping and climate change make the boundaries of these areas and the balance of trees and meadows dynamic.

The amount of solar radiation and UV exposure can vary substantially in our northern latitude largely based on the time of day, slope, season, cloud cover and vegetation.

Because of the extreme temperatures and low precipitation there are few plant species as compared to lower elevation ecosystems and they are simpler in structure.

[10] Increased elevations usually lead to shorter breeding season in animals, as is the case in the alpine ecosystems in the North Cascades.

[10] However, species such as the white-tailed ptarmigan, hoary marmots, and pikas remain in high elevations of the Cascades year round left only to go to patchy and scattered alpine vegetation.

In the winter while there is extensive snow pack there are also strong winds that will expose herbaceous stems and seeds for animals to forage on.

[10] Insects that are blown up from lower elevations will land on the snow beds in the spring offering much nutrition for birds and other mammals that breed in the alpine.

[10] When snowfields melt it creates a gradient of plant phenology which provides emerging vegetation over a period of time for herbivores to feed on and migrate along this line.

[10] Leaf budding and fruiting in late summer past the edges of snowfields also offer food for the animals that depend on this area.

[10] Black bears, songbirds and marmots in the North Cascades and Alpine Lakes can find cover in lush vegetation in avalanche chutes adjacent to the subalpine forests.

[10] Other animal species in the summer months will migrate into the higher alpine elevations to avoid insects and forage in the meadows.

[7] This diverse landscape offers habitat to many species including grazers such as deer, elk, black bear, herbivores, and a variety of birds.

A small number of grizzly bears (Ursus arctos horribilis) inhabit the far northern Cascades, near the Canada–United States border.

[14] Over 75 species of mammals occur in the range, including the mountain goat that lives in the high alpine tundra.

[14] Examples of amphibians occurring in the North Cascades include the western toad, Bufo boreas, and the rough-skinned newt, Taricha granulosa.