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Cottonwood Regeneration Will Protect Montana’s River and Stream Corridors

Cottonwood Regeneration Will Protect Montana’s River and Stream Corridors during Next Flood

August 25, 2011

The floods of 2011 created devastation for many people across the state of Montana. Reconstruction and repair will continue, perhaps for several years, as we try to bring some semblance of normality back to our precious river and stream corridors. Homeowners and farmers are putting their lives back together and restoring homes and farm infrastructure. Government workers and others are designing fixes to irrigation systems, bridges, riverbanks, and roads.

But there is an intriguing natural repair that is appearing on river and stream bottoms everywhere there was high water. It appears that nature has offered a means to protect those riverbanks the next time nature herself unleashes another year like 2011.

Cottonwood tree seedlings have jumped out of the new sediment deposits and bared-off hay and crop fields to carpet large acreages along the Musselshell, Yellowstone, Missouri, and other river floodplains. This year’s dramatic response to a large-scale flood event, combined with the fact that Montana’s cottonwood forests are largely the same age, indicates that cottonwood regeneration on many rivers over the years has probably been “episodic.” It doesn’t happen at a significant scale very often. Large floods along our rivers and their tributaries make it happen.

Why should we protect and manage this new crop of cottonwoods as a buffer along the waterways? Because cottonwoods and other riparian trees and shrubs are critical components of healthy stream systems. Here are a few of the things cottonwoods and other woody plants do for us and other creatures:

  • protect streambanks from erosion with their dense root systems
  • slow down and soak up flood waters across the floodplain, resulting in less water rushing downstream
  • capture and store sediment and nutrients – enriching our floodplain soils and protecting water quality
  • provide diverse wildlife habitat for bald eagles, herons, migratory birds and cavity-nesters, such as woodpeckers, owls, and some song birds
  • provide cool, shaded water for fish and other aquatic organisms
  • add large woody debris to the waterway – providing cover for fish
  • add terrestrial insects, which feeds fish
  • add organic matter fueling the food chain in smaller streams

Fish and wildlife don’t have a monopoly on the benefits provided by cottonwoods. Many livestock producers rely on cottonwood forests for protective cover during severe weather. “Banking” a good share of this year’s flood-induced cottonwood crop will provide future generations of ranchers some storm cover for their herds. Since many of our existing cottonwood forests in Montana are dominated by old and dying trees, we need to act now to regenerate these riparian forests for our children and grandchildren.

As landowners prepare now to disk down or spray these little cottonwoods, I hope they think twice about the tree’s potential to buffer the damage from future large floods and give the watershed resilience: the ability to recover rapidly after a big disturbance. The USDA Natural Resources Conservation Service, conservation districts, and other watershed groups can provide technical assistance, helping people plan for cottonwood regrowth and riparian area management. There is financial assistance available to farmers through NRCS and the Farm Service Agency to offset the costs of installing conservation practices, and in some cases, pay for the buffer you’ve provided for the public good for years to come. For conservation planning assistance, please contact your local NRCS or conservation district office.

photo show thickly growing cottonwood seedings over a broad area near the river.
Numerous cottonwood seedlings grow in new sediment deposited along the Musselshell River by spring and early summer flooding in 2011. These two photos were taken in mid-August of the same year.

Close-up photo of young cottonwoods show how close together they have sprouted.
Cottonwood seedlings grow very thickly in the rich sediment deposits.

photo show thickly growing cottonwood seedings over a broad area with river in background.
By August 2011, cottonwood regeneration was also extensive in areas along the Missouri River that had experienced heavy flooding earlier in the year.