Red Alder (Alnus rubra)
By John Hymas

Our native red alder tree is not showy or particularly appreciated by most people, but this species has been in the environmental restoration business for ages.

Among the first trees to spring up after a flood, landslide, clear-cut, burn or other soil disturbance, red alder often grows in dense stands. It's common to see terrific germination at construction sites or roadways where the ground has been scraped to bare mineral soil.
The primary reason the alder is such an important player in restoration is because it has the ability to enhance soil fertility. This fertility occurs because of a relationship between the tree and soil bacteria. This bacteria invades through root hairs and causes lumps or nodules to form on the roots. The bacteria are able to remove nitrogen from the air and make it available to the host alder tree.

In our forest succession the alder serves as a cover for conifer seedlings, then a nutrient source as they are shaded out, die and release their stored nitrogen. The red alder also loses it's leaves while they are green, providing an annual source of fertility for the plants around it.

The leaves are large, elliptical, with 10-15 parallel veins, and their double-toothed edges are slightly rolled under. The underside is gray-green with tiny rust-colored hairs.

Mature red alder bark is gray-white with black patches and lichen adds a scaly pattern. It has been described as looking, "like a white post that a boy with muddy hands and feet tried to climb.”

One of the first signs of spring is the pinkish-red hue of millions of alder buds against the dull winter green and gray hills. In bloom, the yellowish male catkins (1/2” - 3" long) are obvious, the female 1/4 " cone not so much. The fruit is a small brown cone with tiny flat nutlets, and holds in the tree through the winter.

Red alder is a short-lived tree, rarely reaching 100 years old. It can grow to 100 ft., but 50 - 60 ft. is average.
Rubra, meaning red in Latin, describes the color of the tree's inner bark when exposed to air. Native people use the bark as a dye and for medicines. A valuable hardwood, alder is used to make furniture, cabinets, tool parts, pulp and firewood.