Burn Notice

Invasive cheatgrass sparks more fires in western US

An invasive grass is triggering more frequent fires in the western U.S., researchers say. Cheatgrass is more likely to burn than native plants and has been involved in many of the largest fires that occurred over the last decade.

Scientists have connected several invasive grasses to changes in fire frequency, and previous research in southern Idaho suggested that land overrun by cheatgrass burned much more often than sagebrush. But the authors of the new study, which has been accepted for publication in Global Change Biology, wanted to examine the issue on a larger scale, since cheatgrass-dominated land now extends over more than 40,000 square kilometers of the Great Basin.

The team used several data sets, including satellite data on burned areas and a U.S. Geological Survey fire registry. From 2000 to 2009, cheatgrass land was more than twice as likely to burn as land dominated by any other plant, including sagebrush and montane shrub. Cheatgrass land made up only about 6 percent of the study area, but it covered about a quarter of the land burned by the 50 biggest fires during that time.

Fires that burned longer than one day were also more likely to start on cheatgrass land than on other types of plant cover. The results suggest that “cheatgrass is not only a carrier of fire,” the team writes, but “is also highly flammable and likely to ignite.” — Roberta Kwok | 4 October 2012

Source: Balch, J.K. et al. 2012. Introduced annual grass increases regional fire activity across the arid western USA (1980-2009). Global Change Biology Accepted Article doi: 10.1111/gcb.12046.

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