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The 2017 Thomas Fire (pictured) in California is included in a new analysis of more than 1,500 wildland fires that reveals how drought and fire combine to impact land in the western United States. It was Credit: USDA Forest Service/Stuart Palley
A new study using NASA satellite data reveals how drought affects fire recovery in Western ecosystems, and the results could provide meaningful information for conservation efforts. There is sex.
In the West, the number and intensity of wildland fires is on the rise. Fires, which have historically been a natural part of the region's ecosystem, have been exacerbated by climate change and past firefighting efforts, such as more frequent and severe droughts, and the loss of combustible materials such as fallen branches and leaves. This can lead to accumulation. However, quantifying how fire and drought jointly affect ecosystems has proven difficult.
In the new study, researchers analyzed more than 1,500 fires across the West from 2014 to 2020, and also collected data on drought conditions dating back to 1984. They found that drought conditions make grasslands and shrublands in states such as Nevada and Utah difficult. To recover after a fire, even if it is a less severe fire. Forests, unless severely burned, recover better than grasslands and shrublands because some of the forest's roots can access water deep underground. The team reported the results as follows. natural ecology and evolution.
“Many of the western grasslands are experiencing low-severity fires,” said Shahryar, lead author of the study and a research scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. Mr Ahmad said. “This study shows that even these fires can delay ecosystem recovery if they are preceded by drought.”
If ecosystems don't have enough time to recover before experiencing another drought or fire, the types of plants that grow there may permanently change. This can increase the risk of soil erosion and landslides, and change the normal patterns of water runoff into rivers and lakes.
“Once the fire is extinguished, that's when restoration efforts begin,” said Everett Hinckley, national remote sensing program manager for the U.S. Forest Service, who was not involved in the new study. “Understanding how specific ecosystems and land cover types respond after a fire can inform what actions need to be taken to restore landscapes.”
Without such restoration, a cascade of land cover changes could occur, potentially impacting agriculture, tourism, and other community livelihoods. To track the recovery of various ecosystems, researchers looked at changes in evapotranspiration (ET) (the movement of water into the atmosphere by evaporation from soil and open water and transpiration from plants) before and after fires. Ta. By monitoring evapotranspiration, the team helped determine whether different ecosystems, such as forests and grasslands, had fully recovered after the fires, or whether recovery was delayed or interrupted.
This evapotranspiration data comes from OpenET, a tool that calculates evapotranspiration at a quarter-acre scale across the western United States. This is done using a model that utilizes publicly available data from the Landsat program, a partnership between NASA and the U.S. Geological Survey, as well as other NASA and NOAA satellites.
“This study highlights that changes in vegetation resilience to fire in the West are a dominant control of drought,” said Erin Urquhart, water resources program manager at NASA Headquarters in Washington. Stated. “As climate change continues, land managers, policy makers, and communities need to build on research like this and work together to adapt to these changes, reduce risks, and protect water and other natural resources. Ensuring sustainable use is essential.”
The study also found that forests, grasslands and shrublands all struggle to recover from the droughts that occur around the same time as the severe fires that are common in Western countries. It could lead to potentially permanent changes not only in plant communities but also in regional hydraulics.
The researchers found that severe fires caused significant damage to plants and significantly reduced evapotranspiration in subsequent years. So instead of evaporating into the atmosphere, more water sinks to the ground as a recharge or runoff.
Using a subset of about 800 fires that occurred between 2016 and 2018, the researchers found that across all ecoregions studied, an average of about 528 billion gallons (528 billion gallons) were released in the first year after a fire. It was calculated that 2 cubic kilometers) of water was diverted as runoff or recharge. fire. This is equivalent to one-fourth of North Dakota's annual water demand, or Lake Shasta, California's largest man-made lake.
More water runoff means less water is available for ecosystem restoration and agriculture. As the Earth's climate continues to warm, understanding these changes is important to develop strategies to more effectively manage water resources and ensure water security for future generations.
For more information:
Shahryar K. Ahmad et al., Drought impedes water balance recovery from fires in the western United States, natural ecology and evolution (2024). DOI: 10.1038/s41559-023-02266-8
Magazine information:
natural ecology and evolution