Author: LeeAnn Kriegh | Published: July 21, 2026 | Category: Species Spotlight
This article originally appeared in the Spring + Summer 2026 Desert Ramblings Newsletter.
Our biggest broadleaf tree builds ecosystems
If you love to play in and along rivers and streams of the West, be sure to stop and thank a cottonwood.
Black cottonwoods (Populus trichocarpa) are the tallest broadleaf tree in the West, rising far above relatives like willows and quaking aspens. Partly due to their great size, they’re considered keystone species that provide an outsized impact on life in and along local waterways.
Cottonwoods grow incredibly fast, shooting up in a hurry so they won’t get shaded out by other trees. Their rapid growth makes them ideal for restoring damaged streams, as ONDA and its generous volunteers have done by planting thousands of the trees in the John Day River Basin and along the South Fork of the Crooked River.
During their short lives, cottonwoods provide a long list of ecological benefits. Their high, sturdy branches are valuable nesting spots for large birds like eagles and osprey, and both the branches and trunks feed hungry beavers, who also use the wood to build their dams and lodges. Cottonwoods’ long roots help to prevent streamside erosion, and aquatic species depend on fallen leaves and branches for food and cover.
The ecosystem benefits of these remarkable trees seem to increase as they age and even long after they die. When a strong wind comes along, large branches readily fall off, opening up the trunk—which also hollows out as the tree ages—for insect and bird life. Within a few hundred years, the entire tree dies, and the notably soft, wet wood decays rapidly, supporting an untold number of species.
When you come across one of these tall, beautiful trees in town or in the wild, stop to take a closer look. Check out the heart-shaped leaves, darker on top and lighter on the bottom. Note the ridged trunks on older trees, the many nests in the trunks and branches, and, on female trees, the flower buds that smell like vanilla.
In summer, female trees spread seeds attached to cottony fluff; contrary to popular belief, the “snow” is not an allergen, so there’s nothing to fear. In every season of the year, these exceptional trees provide a welcoming respite for us and the species our lives depend upon.
