Why you should care about cottonwoods
What kind of vegetation can colonize and create tremendous recovery after volcanic eruption? What kind of vegetation can impart the feeling and smell of springtime? What kind of vegetation is bemoaned by many, misunderstood by most and yet one of the most valuable plants to fish, wildlife, and in particular the nesting needs of eagles, ospreys, squirrels and woodpeckers?
These questions pertain to a family of trees and shrubs referred to as Salicaceae. In particular, they were the subject of early ship doctors of the 1870s-1890s who often served on discovery voyages led by Capts. Robert Gray, George Vancouver and James Meares. They described these plants as willows, cottonwoods, poplars and balsam. They were amazed, as should we, by the trees' values. The one I wish to speak of here is the biggest deciduous tree in western North America. We call it the "black cottonwood."
To the Native Americans of that time, all of these plants — from willows to the cottonwood — had noble and valued purposes. Their fiber was malleable, their buds, bark and roots each had great value for weaving and cord-making, and most of all, they provided resources along quiet or rampaging rivers for fish, wildlife and people.
Oregon City, West Linn, Gladstone, Milwaukie, Canby, Wilsonville, Salem and other valley cities have often bemoaned black cottonwood, just one of a family of species with more than 50 members. One value of this tree — willows and others in the family — is recolonizing after floods, volcanic events and landslides. On May 18, 1980, when Mount St. Helens erupted in what we often think as a violent volcanic eruption (but was, in fact, just a moderate one), it was the lowly black cottonwood with willows of various varieties and alders that stabilized nearly 100 miles of denuded riverbanks.
Within two years, hundreds of thousands of acres were brought back into balance by the networking activities of the cottonwood, willow and alder forests.
In the Nile River Delta, poplars and willows to this day are responsible for stabilizing vast tracts of land and making it possible for agriculture to move forward. In our Pacific Northwest region, trees that we consider "undesirable" or sometimes "unreliable" are in fact these Salicaceae trees that provide "just the right stuff."
That is, poplars have the ability to go forth quickly, store huge amounts of carbon in their trees, then make that tissue available for easy cavity nest-site development. If that is not enough, black cottonwood — which can reach 155 feet in height and 10 feet in diameter at Willamette Mission State Park in Salem — are just the right stuff for heron, owl, hawk, osprey and eagles to build their nests within their embracing, broad and branching pattern.
That carbon issue, let's talk about that: One cottonwood tree 100 feet in height and 3 feet in diameter is most often 25 years old — the fastest-growing deciduous tree in the world. That tree will weigh 50 tons. That tree also contains 25 tons of carbon within its stem and an equal amount in the ground. That's equivalent to several automobiles' worth of annual average carbon-dioxide output. The question is why are we not planting such a carbon-sequestering go-getters everywhere we can? The next question might be, "Why are we not doing something to maintain these assemblages that are doing so much work in terms of habitat, landscape stabilization and the carbon cycle?"
In springtime, rain or not, the buds of the cottonwoods and willows in particular are first to shed their sheaths. Black cottonwood bud sheaths are covered with a waxy surface, protecting them during the winter, and then are shed during the first signs of spring. Has anyone ever noticed a spring-like aroma in the air? Most often that is the black-cottonwood sheaths and buds producing the odor of the finest honey.
In addition, we may not notice what the bees and foraging insects do with cottonwood. Throughout the world, they seek out the waxy coverings of poplar buds and its sticky cementing residue to bind their hives together and make them more weather-proof. Native Americans crafted willow, cottonwood and grass-fiber baskets and would waterproof them with the cottonwood's waxy resin.
West Linn's Maddox Woods gardens, on the Willamette River adjoining the Clackamas Rapids and Goat Island, will be celebrating a series of volunteer-led viewings of great blue heron. The herons use the large size and broad branching of black cottonwood for their nest assemblages. Maddox Woods volunteers are going to conduct heron viewings from 1-3 p.m. Sundays, May 19 and June 9, at their observation deck built by Boy Scouts. You can expect to see 50 or more nesting birds at work.
The recent high floods would have not only have impaired, but would also have killed most conifers. That is why conebearing evergreens — including grand fir, Douglas fir, western hemlock and cedar — mostly grow outside the inundation zone. In the inundation zone, our noble cottonwood still does its thing, along with its cousin the willow. They provide huge amounts of food for beavers, muskrats and other foraging animals, even if they're standing in high water.
The bane of the cottonwood of course, is the low durability of the wood and strength of the tree, both of which are concerns to humans. In fact, they are advantages to nesting wildlife, be they in the air or on the ground. The real interesting issue comes when the wind blows the seed pods of this amazing annually reproducing tree. That seed is released when the humidity is high, a southwest flow of wind is underway and rain is certain. Then the seed is released in cotton pods and driven into the ground by the rain on the sandy banks. Amazingly, it germinates within a four-month period. Thus, our lowly cottonwood and many of its cousins are the most adept at restoring disturbed areas.
So let us celebrate, when we can, the smell of spring and the profusion of nesting and downed-woody-materials habitat created by this tree. The cottonwood helps reestablish our planet, providing cover, nestings and other values for us in 2019, just as it did for early people. It may not be popular, but it is a poplar.
Jerry Herrmann is president of Rivers of Life Center, a nonprofit education and training organization for at-risk youth, providing services in wildlife landscaping and environmental tours.