Research finds that when droughts coincide with wildfires, the recovery process takes a significant hit
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The Western United States is no stranger to wildfires. However, a recent study using National Aeronautics and Space Administration satellite data sheds light on a troubling trend: Drought is significantly hindering the ability of ecosystems to recover from these fiery events. This has serious implications for the future health of western landscapes and the communities that depend on them.
The research, published in the journal Nature Ecology & Environment, analysed over 1,500 fires that scorched the West between 2014 and 2020. Scientists also looked at data on drought conditions dating back to 1984.
Read more: Extreme wildfires are turning the world’s largest forest ecosystem from carbon sink into net-emitter
The findings paint a concerning picture. When droughts coincide with wildfires, the recovery process takes a significant hit. Even low-severity fires leave lasting scars on grasslands and shrublands, such as those found in Nevada and Utah, when drought is present. Forests, while generally more resilient, also struggle to bounce back under these combined stresses.
“Many of the West’s grasslands experience low-severity fires,” Shahryar Ahmad, lead author of the study and a research scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said in a NASA press release. “This study shows that even those blazes can trigger a slow recovery in these ecosystems if accompanied by a preceding drought.”
Severe fires — which are becoming more common due to climate change — combined with drought, can lead to potentially permanent changes in plant communities and local water dynamics. When severely burned, plants are less able to take up water, leading to increased runoff and less water filtering back into the ground, the study found.
Read more: UNEP’s Fire Ready Formula: Invest more in preventing wildfires
Researchers also observed a significant decrease in evapotranspiration (the combined process of evaporation from the Earth’s surface and transpiration from plants) in the years following severe fires that occurred during droughts. This suggests that less water is being returned to the atmosphere, potentially impacting regional water cycles.
“This study highlights the dominant control of drought on altering resilience of vegetation to fires in the West,” Erin Urquhart, the water resources programme manager at NASA Headquarters in Washington, said in the release. “With ongoing climate change, it is imperative that land managers, policymakers, and communities work together, informed by such research, to adapt to these changes, mitigating risks and ensuring the sustainable use of water and other natural resources.”
Insufficient time for ecosystems to recover between droughts or fires may result in permanent alterations to the plant species composition, the researchers underlined. Consequently, this could elevate the likelihood of soil erosion, landslides, and disrupt typical water runoff patterns into streams and lakes.
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