Beavers Dams Create Healthy Downstream Ecosystems

摘要

Beavers are much more than cute critters with impressive building skills. Long known for their beneficial effects on the environment near their dams, beavers are also critical to maintaining healthy ecosystems downstream, according to recent research. Researchers have found that ponds created by beaver dams elevated downstream groundwater levels in the Colorado River valley, keeping soil water levels high and providing moisture to plants in the otherwise dry valley bottom. The results were published in the June 8 issue of Water Resources Research, a journal of the American Geophysical Union (AGU; Washington, D.C.). Cherie Westbrook of Colorado State University (Fort Collins), her colleagues, and scientists from the U.S. Geological Survey conducted a 3-year study in northern Colorado's Rocky Mountain National Park, examining valley ecosystems downstream in the Colorado River. They noted that water diverted by beaver dams is forced out of the natural stream channel and spreads across and down the valley for hundreds of meters. In addition, beaver dams built on the river changed the direction of groundwater flow in the valley. The changes caused water to infiltrate the river banks and flow underground toward the sides of the valley, instead of down the center of the valley, an AGU press release states.