Your vision of a rainforest might run toward palm trees and tropical birds. You may be surprised, but the definition of a rainforest is actually a little different. Rainforests are characterized by the amount of rainfall they receive in a year. In the Pacific Northwest temperate rainforests, which you can find along the California coast and up into Canada, this can be more than 10 feet of rain per year. Moderate temperatures in both the summer and winter also define these areas.
In fact, these temperate rainforests can be far more productive than any tropical rainforest—up to four times more productive as far as biomass. This includes living and decaying material from trees, soil, shrubs, and mosses. Often, these forests will grow right up to the shoreline of the Pacific Ocean.
If you’re interested in seeing these forests up close, visit Olympic National Park or the Redwood National and State Parks. While you’re there, Mr. Tree has a list of some of the beautiful trees you’ll find in these Pacific Northwest rainforests.
1. Sitka Spruce
These temperate rainforests are composed mainly of conifers of one kind or another, chief of which is the Sitka spruce. This majestic species can grow as tall as 330 feet tall and can have a trunk diameter more than 16 feet wide. It is the third tallest conifer species, only after the coast redwood and coast Douglas fir. You can identify this species not only from its height, but also from its thin, scaly bark, which sheds little discs.
Logging of these trees began before precise measurements could be taken, but these days, the tallest specimens may be found in Pacific Rim National and Carmanah Walbran Provincial Parks. In Olympic National Park, you’ll find the Queets Spruce, which is the largest Sitka spruce tree in the world. This beautiful spruce is 244 feet tall and has a diameter of 14.5 feet. At 350 to 450 years old, it is only beginning to enter its middle age. Sitka spruces are a long-lived species, with individuals being known to live for over 700 years.
2. Bigleaf Maple
Also known as the Oregon maple, this is one of the deciduous species in these lush rainforest locations. They are the largest type of maple tree that grows in the area. However, they don’t grow nearly as tall as the Sitka spruce. Usually, a bigleaf maple will grow to 15 or 20 feet tall.
There are several cultivars of the bigleaf maple—cultivars are varieties of a species that was produced by selective breeding. First is the Mocha Rose, on which the foliage grows red flowers and shows various shades of pink in the growing season. There is also the Santiam Snows, which has green leaves speckled with white. The Seattle Sentinel is characterized by its upright, columnar look and its vibrant gold shade in the fall.
You may think that only East Coast maples give syrup, but these maples are able to do it too. However, there isn’t much demand, and commercial interest is low since the flavor is different from what you’d expect, though it has the same sugar concentration.
3. Coast Redwood
This one goes by several different names, including sequoia, coastal redwood, and California redwood. If you thought the Sitka was long-lived, the redwood is practically immortal. These trees have been known to live for 2,200 years or more and are among some of the oldest living things on Earth, period. You’ll find these regal trees along the coast of southwestern Oregon and most of the California coast, including Southern California. Rainfall is much more limited there, so these trees tend to be not as tall as their northern counterparts.
Unlike the other trees listed here, redwoods tend to have much thicker bark, making them more fire-resistant than the spruce and the maple. These trees love water: the tallest of them live in valleys where regular year-round streams flow and where fog drip is almost continuous. They can live at sea level but are most successful if they live at a slightly higher elevation and inland, where the incoming precipitation from the ocean is higher.
These trees are members of the birch family and are vital to the success of the Pacific Northwest rainforests because they are nitrogen fixers. The trees themselves do not handle this, but they have a symbiotic relationship with a nitrogen-fixing bacterium called Frankia alni. The bacterium lives in root nodules of the alder trees and absorbs ambient nitrogen in the air. The alders then use the nitrogen and improve the fertility of the soil around them. New species and other plants then find it easy to establish themselves in the area. In return, the bacterium receives sugars from the tree, which it creates through photosynthesis.
Forests with alders are typically healthier and lusher and are able to resist forest fires. Not only are the trees less flammable than conifers, but the foliage and leaf litter make it difficult for surface fires to catch and spread. After a major flood, windstorm, or other event, the first trees to recolonize an affected area will usually be alders.
5. Shore Pine
This evergreen conifer was historically used by the indigenous people of the Pacific Northwest, both internally and externally, as traditional medicine. One use was as an antiseptic for wounds and infections. You can also extract turpentine from the resin, which is a diuretic and was used in the treatment of kidney and bladder complaints.
This tree and its variations grow widely across North America. You can identify this tree most easily through the shape it creates—the crown of the tree is rounded, and the top of the tree has a “flattened” appearance. Some populations in British Columbia also form twin trees. There are four varieties of this species altogether, and one of them is a shrub. The tallest of them can reach 130 to 150 feet tall, while the shrub grows only 3 to 10 feet high.