Sixty years ago, I lived just a few hundred feet from the banks of Cherry Creek, which was lined with groves of majestic cottonwood trees. And every year, as summer approached, we kids enjoyed the “snow.” It wasn’t the wet snow of winter, but that of near-summer: a profusion of cottonwood seeds, attached to “cotton” tufts, blowing in the breeze. In my memory, it piled up like snowflakes ankle-deep.
I doubt I connected the flurry of cotton to the trees along the creek. Certainly I didn’t know that the creek and its banks and the trees and the “cotton” were all linked in a magical way. In those days—the late 1950s and early ‘60s—the term “ecosystem” had been coined but not yet taught in schools. Later I would learn about the very essence of an ecosystem: the interconnectedness between plants and animals and water and wind and soil and climate in a geographical area. How they all work together to form an intricate, exquisite net.
In late spring, mountain snowmelt heads downland and pours into rivers and streams and creeks, resulting in rising water levels. As the water moves higher and faster, it scours the riverbeds and flushes away vegetation detrimental to the river. It is at this time of year when levels reach their highest point; it’s called the “June Rise.”
When the water begins to recede, it is then, like magic, that female cottonwoods release their cotton-attached-seeds to the wind — an ancient, primitive method of procreation.
A mature female tree will disperse 25 million seeds or more in a single season. Few of these seeds, tiny voyagers the size of a pinhead, land “on target,” settling instead on roadways and window screens, in gutters and barbecue pits. But a fortunate few will drift downstream in the wind or water and land on a perfect, bare, moist spot, often on the side of the freshly-scoured riverbed. The conditions and timing must be just right.
If the seed makes it this far, it still needs moisture and sunlight to germinate. But if successful and left undisturbed, it can put down roots from 3-5 feet in one summer. The seedling still has challenges to face: summer droughts, hungry animals, hard summer downpours. But it has gotten a good start.
Once grown, cottonwoods provide habitat for 80% of Colorado’s bird species, according to Kathleen Cain in her book, “The Cottonwood Tree: An American Champion.” Eagles and hawks and herons use their thick branches for nesting. Numerous species dwell in the cavities, including Northern flickers, black-capped chickadees and red-headed woodpeckers.
The rivers depend upon cottonwood trees, too. The trees serve to anchor the banks, stabilize the soil, and prevent erosion. Their shade helps moderate water temperatures for the survival of many aquatic species. The organic matter that drops from the trees feeds microorganisms and insects, which in turn feeds the fish. Interconnectedness.
Cottonwoods once served as beacons for weary Western pioneers, signaling the presence of water. Their huge canopies offered refuge from the unrelenting heat. Often they were the only trees travelers encountered on the plains.
Now, in many areas of Colorado, we’re in danger of losing this priceless native champion. Climate change has already caused critically low water levels, and efforts to protect rivers seem to have gone by the wayside. Cities and municipalities everywhere are clamoring for more water to support their new developments. Plans for new dams are in the works.
Whenever we build dams or divert water from our rivers, when we manipulate the flow rates, the changes can be brutal for the survival of our cottonwoods. The cotton still flies, but the “June rise” isn’t high or vigorous enough to create the right conditions for regeneration.
And those cottonwoods we do have often compete for water with non-native trees, such as the Russian olive or the tamarisk tree, which poisons the soil and crowds out native flora. Cottonwood trees are resilient but they aren’t invincible. When they disappear, birds and other animals that depend upon these trees will begin to disappear as well. The net will tear, and keep tearing, and there’ll be no way to mend it.
It’s so easy to take trees and rivers and birds for granted. I know I have. But the possibility of their disappearance is real, and critical, and just in front of us. I hope we can join together, today, to save what we can for generations to come. Life goes by so quickly.
Colleen Fullbright lives in Fort Collins.
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