Riparian environments in Colorado would not function properly without the humble river willow amongst its ranks.
These small, spindly, bush-like willows are a far cry in appearance from their larger cousins like the weeping willow. Though, what they lack in physical stature is more than made up for by the benefits they provide to their ecosystems.
There are several species of willow native to Colorado, with varieties that grow at almost every elevation. Even mat-forming species of willow can be found above tree line.
Willow identification can be tricky, but some common species of willow found in our area are coyote, planeleaf, mountain, and Scouler’s willow.
Willows in general can be identified from their slender reddish-brown stems and branches; narrow, elongated leaves; and catkins that develop early in spring. More specific ID will certainly require a more trained eye.
They prefer moist soil and full sun, hence their predominance in local wetlands, flood plains, and along stream banks and riverbanks.
They provide habitat for many birds and small critters, notably the endangered Southwest willow flycatcher, which has become endangered due to riparian habitat loss. Willows are a favorite of grazing wildlife species like deer, elk and moose. They help prevent streambank erosion and aid in absorbing flood water.
Their root systems can even act as a natural filter, improving water quality. Canopies of willow growing on streambanks provide shade, cooling stream water, while roots stabilize and create overhanging banks, providing habitat for fish and other aquatic organisms.
In traditional cultures of the Western U.S., the willow was used in many aspects of daily life. Willow branches were used as building materials to make all sorts of items from baskets, looms, boats, snowshoes and arrows to willow-framed dwellings sheathed with cattails. The Ute used to concoct a green dye for coloring buckskin by soaking willow leaves in hot water and then boiling the mixture to concentrate the pigment. The bark of willow was used as a natural pain reliever and inflammation reducer. Aspirin itself is a derivative of salicylic acid — a compound found in Salicaceae family members. In all areas where willows grow natively, there is a long history of human use associated with these plants.
Despite the abundant goodwill these trees bring to their surroundings, too much willow can be problematic. Overpopulated thickets of willow can crowd out access to waterways for both recreating humans and water-seeking wildlife alike. They can form monocultures that shade out riparian undergrowth, reducing biodiversity. Willows can clog up irrigation ditches, reducing the amount of water available for use and providing habitat for unwanted animals in the ditches. Property owners along streams and rivers may find themselves constantly fighting back the willows from encroaching onto their land.
Controlling the willows can indeed be a challenge. Mechanical removal by pruning, brush-cutting or masticating can be effective, but the willows regrow from the root systems quickly and consistently send up new shoots to continue their spread.
Logistically, getting heavy machinery in these wetland areas to remove willows can be a dangerous endeavor, and may cause unintended damage to stream banks and sensitive wetland environments.
A combination of mechanical removal and herbicide applications of an aquatic labeled herbicide (i.e. 2,4-D or Triclopyr) may be a more effective approach. Clearing an area of willow and spraying the regrowth with herbicide can be more effective than just doing one or the other method.
Regardless of your chosen control method, it will have to be done several times to see lasting results.
Keep in mind, however, the important role the willow plays in the ecosystem before clearing stands of them. Removing them will not only reduce wildlife habitat, but provide an opportunity for the invasive tree tamarisk, or salt cedar, to establish in its place.
Tamarisk is one of the biggest threats to riparian ecosystems in the Southwest U.S. Intentionally introduced for bank stabilization, tamarisk can change soil salinity to dangerously high levels, preventing native plants from growing. They also suck up a disproportionally large amount of water compared to native riparian plant life. They do still provide habitat; the southwest willow flycatcher has taken up residence in these trees due to displacement of willow, making control of tamarisk even more complex.
Archuleta County Weed and Pest is your local resource for managing noxious weed populations and controlling other pests.
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