October 9th, 2012 by

Flooding in southwest Washington

Flooding in southwest Washington. Credit: Washington State Department of Transportation (WSDOT)/Flickr

Maybe it’s because I grew up as a snowbunny, skiing the slopes of the Rocky Mountains during many a spring break, but one of my favorite “ecosystem functions” of forests is their impact on snow. When I accidently hugged that tree at age 12, I had no idea how grateful I should have been that it was there.

As many a forest lover knows, trees have multiple impacts on snow, including slowing its melt through the shade they provide and stabilizing the soil upon which it lies. While these might seem like simple things, a new study makes it clear just how vital these functions are.

Kim Green and Younes Alila’s new research published in Water Resources Research reveals that deforestation doubles — and may even quadruple — the number of large floods in waterways affected by those forested areas. Studying data from four creeks in Colorado, the authors discovered that deforestation caused 10-year floods to occur every three to five years, 20-year floods every 10 to 12 years and 50-year floods every 13 years! As Green mentions in the announcement on the study’s publication, “Once you look at how the frequency has changed, you start to realize that deforestation has had a pretty dramatic effect on floods.”

Glacier National Park, Montana

Glacier National Park, Montana. Credit: dr-scott/Flickr

Unfortunately, deforestation isn’t the only way we’re losing forests’ impact on snowy peaks. In the Mountain West, white pine blister rust and mountain pine beetles are decimating five-needle pines that live at high-altitudes. More than 40 million acres of forest across 10 states in the West are thought to be dead or dying. Since these pines live at high-altitudes, they play a significant role in protecting the snow and water supply, which is just one of the reasons American Forests is working to restore these endangered western forests.

If we continue to lose high-elevation forests to deforestation, disease and pests, we could be facing serious financial and health consequences. The National Oceanic Atmospheric Administration reports that the 30-year average per year for flood damage is $7.82 billion. If the frequency of flooding events increases, so too will this figure. Plus, more than half of the drinking water in the U.S. originates in forests. Both of these seem to be pretty convincing arguments as to why we should be deeply concerned about the state of our forests and how they are protecting our nation’s beautiful, snow-capped peaks.