Cheatgrass (Bromus tectorum) is an annual grass native to southern Europe, northern Africa, and southwestern Asia. Cheatgrass changes the frequency, extent, and timing of fires. It matures earlier than most native grasses and tends to occupy openings that would otherwise contain sparse vegetation, promoting earlier and more continuous fires. Cheatgrass is also very flammable, increasing the chance of ignition. In Sequoia and Kings Canyon National Parks, cheatgrass has become abundant in many areas, particularly in the Cedar Grove area on the South Fork of the Kings River. It is found throughout the parks in dry locations on road- and trail-sides.

Identification

Cheatgrass is typically short, with conspicuously hairy leaves. Foliage is bright green as a seedling, reddish at maturity, and light tan after maturity. The head is dense, slender, usually drooping, and one-sided.

NPS photo

The cheatgrass head is dense, slender, usually drooping, and one-sided.

Look-Alikes

The drooping appearance, short stature, and hairy leaves of cheatgrass are distinctive in combination. Other native grasses with drooping heads may be confused with cheatgrass. Another non-native species, Bromus arenarius, has a similar drooping head, but differs in being larger and more robust.

Natural History

Cheatgrass establishes by seeds only. Seed production is very high, with single plants producing in excess of 300 seeds. As a winter annual, cheatgrass germinates in the fall if moisture is adequate, which allows it to mature early in the spring before most native herbaceous plants. Cheatgrass can interfere with seedling establishment of native woody shrubs and trees that require canopy openings or disturbance to germinate.

In Sequoia and Kings Canyon National Parks cheatgrass is widely distributed at elevations between 600 and 2500 meters (2,000 to 8,000 feet). While many of the populations are restricted to roadsides, trailsides, and disturbed areas, many other populations exist in undisturbed open areas on well-drained soils. Cheatgrass is notably absent in some wilderness areas of the park such as the Sugarloaf and Roaring River areas, and is present in relatively low abundance in the Kern River watershed.

USGS Photo

Cheatgrass is rapidly spreading into parts of Sequoia and Kings Canyon National Parks.

Management

Because cheatgrass is widespread in Sequoia and Kings Canyon National Parks, control is unfeasible in many locations. Priorities are to keep cheatgrass from spreading into currently uninfested areas, such as the Sugarloaf and Roaring River areas, and to consider control in high-value wilderness areas with low cheatgrass abundance, such as the Kern Canyon.

Cheatgrass is currently being controlled in frontcountry areas with high potential to spread cheatgrass to wilderness, such as pack stations and some campgrounds and trailheads. Small patches are pulled by hand, whereas large, dense patches that are unfeasible to pull by hand are sprayed with approved glyphosate herbicides.

Cheatgrass also has implications for the way fire is managed in the parks. In 1998 the National Park Service noticed a significant increase in cheatgrass distribution and abundance in the South Fork of the Kings River (Cedar Grove area) in areas where prescribed fire had burned. Park managers were concerned that continued burning in these dense patches or nearby areas would promote its success and spread. Burning on the valley floor of Cedar Grove was suspended until the problem could be studied further.

In 2001, researchers from the United States Geological Survey began studying how cheatgrass was affected by season of burning, soil moisture, fire intensity, and shade. Their study showed that altering burning season to coincide with seed maturation in the spring is not likely to control cheatgrass because sparse fuel loads generate low fire intensity. Increasing time between fires may inhibit cheatgrass by increasing surface fuels, which directly inhibit cheatgrass establishment, and by creating higher intensity fires capable of killing a much greater fraction of the seed bank. In 2005, prescribed burning resumed in the Cedar Grove area. Park staff continue to investigate how fire and cheatgrass interact in the parks.