Charred Forests, Melting Snow
A study, conducted by Oregon State University researchers, funded by the National Science Foundation and published in Geophysical Research Letters, found that snowpack melts faster in forests which have been charred by wildfire. The researchers explain that as the charred particles are shed from the tree throughout the winter, they darken the snow, reducing its reflectivity.
How much of a difference could a few burned bits make? The researchers found a 40 percent decrease in the surface’s reflectivity, or “albedo,” and a 60 percent increase in solar radiation reaching the snow’s surface. At a test site 5,000 feet in elevation in Oregon’s Cascade Range, snowpack was found to disappear 23 days earlier due to the phenomenon. The shedding of charred particles after a burn will last at least two years and can last as long as 10, so these effects could be seen for multiple winters.
While fires are a natural part of these forest ecosystems, the situation today is compounded by an increase in the intensity of wildfires, as well as the expected increase in wildfire numbers due to climate change. In high elevations of the Rocky Mountains, such as those in the Greater Yellowstone Area, climate change has led to earlier snowmelt in other ways as well. As warming temperatures have allowed for a population boom of mountain pine beetles, the whitebark pine trees that provide the shade and soil stability that aid in retaining snowpack are dying, leading to earlier melting.
Earlier snowmelts have the potential to wreak a lot of havoc on communities. In addition to increased flooding, a faster snowmelt can also alter an area’s water supply. As spring runoff begins earlier, it may not last as late into the year. The study’s findings could help resource managers plan for fluctuations in water availability.
At American Forests, we advocate for sound policies to manage wildfire and the complications that are arising as the climate changes. We also launched our Endangered Western Forests initiative to address the challenges of the whitebark pine.
As study co-author Anne Nolin asks Phys.org, “What does it mean for your water supply when headwater catchments burn, the snow melts faster and the spring runoff begins even earlier? It is a provocative question for resource managers.”