Tuesday, April 19, 2016

Post Fire Erosion is Shaping Landscapes in the West

Jon Pelletier, a University of Arizona professor of geosciences, walks through the forest on Cerro del Medio, a mountain in New Mexico's Valles Grande, after the 2011 Las Conchas fire. Photo: Caitlin Orem
Erosion after severe wildfires can be the dominant force shaping forested mountainous landscapes of the Intermountain West, suggests a new research paper by two University of Arizona geoscientists. The study is the first to assess the impact of wildfires on such landscapes by combining several different ways to measure short-term and long-term erosion rates. 

"We knew that wildfire increased the rate of erosion, but we didn't know how important it was over long time scales," said first author Caitlin Orem.  
Once the 2011 Las Conchas fire burned this forested region of New Mexico's Valles Grande, water from summer rainstorms tore this ravine through a grassy meadow.  Credit: Caitlin Orem

Orem and Pelletier calculated total erosion rates for their study area for time scales up to 1 million years ago. The scientists found more than 90 percent of the erosion happened in the geologically brief time intervals right after forest fires. Those post-fire intervals constituted just 3 percent of the total time.

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