What is in this article?:
- Western fires worse due to invasive cheatgrass
- Remote-sensing technology
- Cheatgrass is involved in a disproportionately high number of fires in the Great Basin, a 600,000 square-kilometer arid area in the West that includes large sections of Nevada, as well as parts of Utah, Colorado, Idaho, California and Oregon.
- The fires can threaten agricultural lands and, since more people are building homes in the west, residential areas as well as habitat for threatened native wildlife.
Balch said the cheatgrass-influenced fires create a difficult management challenge. The fires can threaten agricultural lands and, since more people are building homes in the west, residential areas as well as habitat for threatened native wildlife, such as the greater sage grouse.
While cheatgrass-driven fires have been recognized for decades, remote sensing technology has allowed the researchers to take a regional approach to assessing the problem. They compared burned area detected by NASA's Moderate Resolution Imaging Spectoradiometer between 2000 to 2009 to regional land cover maps that included cover of cheatgrass.
"Historically, the way remote sensing worked, you could only tell the difference between broad land cover classes such as trees versus wetlands, for instance," Bradley said. "It is very difficult to capture those details at the species level."
However, by noticing what conditions favor the growth of certain species, the researchers were able to use the satellite imagery to better pinpoint the growth of different species. For instance, cheatgrass grows during wet periods while many other species do not, Bradley said.
"What you end up seeing is that most years when it is dry, the cheatgrass doesn't grow much," said Bradley. "But when there are wet seasons that occur due to the El Nino cycle, cheatgrass cover is very dense and continuous."
Bradley added that this is a concern because cheatgrass now dominates more than 40,000 square kilometers, an area that is more than 100 times the size of Salt Lake City, Utah.
According to the researchers, those changes in the vegetation can be detected in the satellite images.
"Being able to detect cheatgrass and burns really enabled us to ask the important question: 'How does an invasive plant change fire activity across the entire Great Basin?'" Balch said.
The National Science Foundation and the National Center for Ecological Analysis and Synthesis supported this work.