An Invasive Grass Species Spreads Wildfires Quicker


A continuous cover of cheatgrass fuels an intense fire in the American West. Credit: Mike Pellant/BLM

New research indicates that an invasive species of grass is making wildfires in the western USA larger, hotter, and more frequent. A variety of grasses called cheatgrass dries out quickly, and burns more rapidly than other vegetation.

The scientists published their findings in the journal Global Change Biology. The researchers believe that it has fueled almost 80% of the largest fires in the American West over the last decade. The scientists are looking at a wide range of solutions for solving this problem, including using a fungus to attack the grass seed.


Satellite imagery shows that cheatgrass-dominated areas burned more rapidly and more frequently. Credit: NASA

The seeds were originally transported to the USA in soils on board ships. The weedy grass continued its journey west in the 1800s with settlers and cattle ranchers. The grass grows very quickly and dies, cheating other grasses out of valuable nutrients. It’s widespread throughout the Great Basin of the American West, in an area of 600,000 square kilometers (232,000 square miles), which covers parts of Nevada, Utah, Colorado, Idaho, California, and Oregon.

Scientists have long suspected that it played a key role in wildfires, but this is the most current study yet, which used satellite imagery from NASA to compare burnt areas with regions where cheatgrass dominates.

This species was easily picked out from space because it dries out earlier than native species. It influences a majority of the large fires, and it’s also fueling them. From 2000 to 2009, cheatgrass influenced 39 of the 50 largest wildfires. Cheatgrass promotes fires that are easily ignited and spread rapidly. It’s suggested that cheatgrass and fires are in a mutually beneficial relationship since the fires help cheatgrass outcompete other species and expand its range faster. Fires help spread the invasion and cheatgrass could be extending the fire season across the Great Basin.

Strategies for dealing with this threat involve brute mechanical removal or introducing a fungus that attacks the seeds.

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