Invasive Cheatgrass Triggers Frequent Wildfires in Great Basin

Invasive cheatgrass is causing frequent wildfires in the Great Basin, reveals a new study.

A team of researchers led by Jennifer Balch from Penn State University examined wildfire data along with satellite images of the Great basin obtained from NASA's Moderate Resolution Imaging Spectoradiometer. The Great Basin is a large area composed of arid lands that stretch across Utah, Colorado, California and Oregon.

The research team found that 39 of the 50 biggest wildfires recorded from 2000 to 2009 in the Great Basin were caused by cheatgrass. These are invasive species that were accidentally introduced by settlers in the West during the 1800s.

"Over the past decade, cheatgrass fueled the majority of the largest fires, influencing 39 of the largest 50 fires," Jennifer Balch, from Penn State university, said in a statement. "That's much higher than what it should be when you consider how much of the Great Basin that cheatgrass covers." 

The average size of the fires in regions of Great Basin where cheatgrass dominates (6 percent of Great Basin is covered by cheatgrass) was larger than the average size of the fires in regions covered by other vegetations including pinyon-juniper, montane shrubland and agricultural land. Experts observed that the cheatgrass burned twice as much as any other vegetation.

They suggest that the lands covered by cheatgrass have shorter fire-return intervals - 78 years compared to other species like sagebrush, which has a 196-year fire return interval. Cheatgrass is causing a grass-fire cycle, where the grass promotes the fire and fire promotes the grass. This might likely cause more frequent wildfires in the future, say the researchers.

The invasive species has the ability to spread faster and cover more areas, causing more frequent blazes. Cheatgrass does not grow when the conditions are dry. But during the wet season, which is trigged by the El Nino cycle, the grass covers dense areas continuously. It is now dominating more than 15,000 square miles (40,000 square kilometers). 

The invasive species does not provide any nutrients or shelter for wildlife like the native grass do, Los Angeles Times reports.

This could cause a huge habitat loss for a wide range of species living in the Great Basin. The fire caused by cheatgrass could pose a major threat to agricultural lands as well as residential areas in the region, the researchers point out.

The findings of the study,"Introduced annual grass increases regional fire activity across the arid western USA (1980-2009)," appear in the online edition of journal Global Change Biology.