Low-severity wildland fires and prescribed burns have long been presumed by scientists and resource managers to be harmless to soils, but this may not be the case, new research shows.
Low-severity wildland fires and prescribed burns have long been presumed by scientists and resource managers to be harmless to soils, but this may not be the case, new research shows.
According to two new studies by a team from the University of California, Merced (UCM) and the Desert Research Institute (DRI), low-severity burns – in which fire moves quickly and soil temperature does not exceed 250oC (482oF) – cause damage to soil structure and organic matter in ways that are not immediately apparent after a fire.
“When you have a high-severity fire, you burn off the organic matter from the soil and the impact is immediate,” said Teamrat Ghezzehei, Ph.D., principal investigator of the two studies and Associate Professor of Environmental Soil Physics at UCM. “In a low-severity fire, the organic matter doesn’t burn off, and there is no visible destruction right away. But the burning weakens the soil structure, and unless you come back at a later time and carefully look at the soil, you wouldn’t notice the damage.”
DRI researcher Markus Berli, Ph.D., Associate Research Professor of Environmental Science, became interested in studying this phenomenon while visiting a burned area near Ely, Nev. in 2009, where he made the unexpected observation that a prescribed, low-severity fire had resulted in soil structure damage in the burned area. He and several colleagues from DRI conducted a follow-up study on another controlled burn in the area, and found that soil structure that appeared to be fine immediately after a fire but deteriorated over the weeks and months that followed. Berli then teamed up with Ghezzehei and a team from UCM that included graduate student Mathew Jian, and Associate Professor Asmeret Asefaw Berhe, Ph.D., to further investigate.
Read more at Desert Research Institute
Image: In semi-arid ecosystems such as the Humboldt-Toiyabe National Forest near Las Vegas, which burned as part of the Carpenter 1 fire during July and August 2013, fuel is limited and fires tend to be short lived and low in peak temperature. New research shows that these fires are more harmful to soils than they initially appear. This photo was taken on Jan. 6, 2015 -- approximately 18 months after the wildfire. (Credit: Teamrat Ghezzehei, UCM)
