Alnus rubra, the red alder,[3][4] is a deciduous broadleaf tree native to western North America (Alaska, Yukon, British Columbia, Washington, Oregon, California, Idaho and Montana).

[8] In moist forest areas, Alnus rubra will rapidly cover a former burn or clearcut, often preventing the establishment of conifers.

This association allows alder to grow in nitrogen-poor soils, and makes the species an important early colonizer of disturbed forests and riparian areas.

This self-fertilizing trait allows red alder to grow rapidly, and makes it effective in covering disturbed and/or degraded land, such as mine spoils.

[12] Alder leaves, shed in the fall, decay readily to form a nitrogen-enriched humus making the nitrogen available to other species.

), red osier dogwood (Cornus stolonifera), Oregon ash (Fraxinus latifolia), and bigleaf maple (Acer macrophyllum).

[8] Native Americans used red alder bark to treat poison oak reactions, insect bites, and skin irritations.

Recent clinical studies have verified that red alder contains betulin and lupeol, compounds shown to be effective against a variety of tumors.

Alnus rubra are occasionally planted as ornamental trees and will do well in Swales, riparian areas, or on stream banks, in light-textured soils that drain well.

The appearance of alder lumber ranges from white through pinkish to light brown, has a relatively soft texture, minimal grain, and has medium luster.

Since most forest land in the Northwest is managed for conifer production, over 200,000 acres (80,000 hectares) of timberland are sprayed with herbicides annually in Oregon alone to control red alder and other competing hardwood species.

[21][22] In addition to adding soil nitrogen, rotations of red alder are used to reduce laminated root rot in Douglas-fir forests.

[24] This interest is limited by red alder's total stand productivity, which is significantly lower than that of Douglas-fir and western hemlock.