Cheatgrass: threatening homes, stealing rangelands

By John Fairchild
Division of Wildlife Resources

Virtually every part of Utah is within a watershed, and some areas are more threatened than others. Sagebrush and pinyon-juniper areas — dry, rugged terrain between the desert lowlands and the areas above about 7,500 feet — are especially at risk across the state and across the West.

Western landscapes are burning now more than ever, and Utah is no exception. With rangeland fires through sagebrush ecosystems now twice as common as they were before the settlers arrived, constant fires are becoming a major threat to our watersheds.

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Each year in Utah, cheatgrass-fueled fires burn thousands of acres of imporant rangeland.

Why is Utah burning? Surprisingly, an unassuming grass is the culprit. Not native to North America, cheatgrass has invaded our natural areas and it's spreading rapidly.

Cheatgrass grows faster than native plants, and becomes established early in the growing season, monopolizing water and nutrients. Its seeds are set long before those of native plants, making it hard for native plants to compete. The dense stands of cheatgrass are easily ignited, and fires spread quickly through the grass.

Cheatgrass is unaffected by the fires, coming back even stronger the following year, while native plants struggle. It's a cycle that will continue unless we step in and set a new course for our watersheds.

You probably saw the scene on more than one news broadcast in Utah this past year. With flames burning within sight of homes in the background and air tankers dropping fire retardant out of the sky, the reporter stoops down and points to the culprit behind the rangeland fire you're witnessing; a highly flammable, non-native grass called cheatgrass.

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Cheatgrass

Cheatgrass

Also known also as "junegrass" and "downy brome," cheatgrass escaped from its native Mediterranean rangelands in the late 1800s and found its way to the Columbia River Basin in contaminated grain seed. By 1920, it was well established. It's been increasing throughout Utah and the Intermountain Region ever since.

Cheatgrass deserves the "culprit" status reporters often give it but because of time constraints, reporters can't tell you the whole story on the six o'clock news. That's because there's so much to the story and the changes that are taking place on our rangelands have been "in the works" for a long time.

Unfortunately the impact of this story, to wildlife habitat and Utah's wildlife, is unprecedented.

Fires more often and more intense

Few invasive weeds have affected semi-desert plant communities in the Intermountain West more than cheatgrass.

In these areas, moisture in the soil is at a premium, and cheatgrass, with its long history of adaptation to similar sites in the Mediterranean Region, easily out-competes native plants for moisture and nutrients. The seeds of cheatgrass germinate and the plant establishes itself in the fall and winter. As a winter annual, it "robs" moisture and nutrients from the soil when native grasses and forbs are still dormant.

This early activity by cheatgrass has a two-fold effect: it limits the growth of the native perennials and prevents the establishment of their seedlings. Cheatgrass reaches maturity and sets seed four to six weeks before the native perennial grasses. By June, cheatgrass has cured and is ready to burn with the first lightning strikes of the year.

And the presence of dried fuel early in the year is only part of the problem. The change that a cheatgrass invasion brings to the structure of a plant community is what distinguishes the type of fires we're seeing today from those as recent as only 20 years ago.

Historically, Utah's rangelands were dominated by perennial bunchgrasses. As the name implies, bunchgrasses grow as individual plants in "bunches." Sites dominated by bunchgrasses have more open space between plants, and the plants stay green longer into the growing season. When a fire starts in an area dominated by bunchgrasses, there is a greater chance that it will die out because of the sparse vegetation. Typically, fewer acres are burned and the post-burn landscape is generally a mosaic of burned and unburned areas.

The result is much different in areas invaded by cheatgrass. Cheatgrass fills the spaces between the bunchgrasses, creating a continuous cover of highly flammable fuels. What was once a sparsely vegetated, fire "resistant" area, is now a dense, dry tinderbox. When ignited, wildfires spread through cheatgrass-dominated landscapes quickly and completely, consuming a much larger area.

The cheatgrass invasion has done more than just increase the acreage burned annually in the West. It has also dramatically changed the fire frequency. In native shrub-bunchgrass ranges, fires occurred every 30 to 75 years. In cheatgrass ranges, fires occur every 10 years or less (three- to four-year cycles are common in cheatgrass-infested areas).

The increase in fire frequency has eliminated most shrubs and reduced the density of native bunchgrasses and forbs. The native plant communities that support Utah's wildlife are being wiped out at an alarming rate.

However, as damaging as the cheatgrass invasion has been, it's not the only "culprit" cheating us out of healthy rangelands. Remember, understanding the whole story is never that simple.

Pinyon-juniper contributes to the problem

As damaging as frequent fires can be to native plant communities, the complete absence of fire can have similar consequences. Without periodic fires, sagebrush and pinyon-juniper can completely dominate their respective sites.

The combination of increasing dominance by woody plants, the historic overgrazing of western ranges by livestock in the late 1800s and early 1900s, and well-intentioned fire suppression efforts by state and federal land management agencies over the last 50 years, have produced conditions for the "perfect storm" in terms of wildfires on many of our western ranges. These stands no longer sustain a diverse understory of native grasses and forbs, and they don't have the seed reserves in the soil to get them reestablished after a wildfire. The sagebrush stands have become dense, old and decadent, and closed-canopy pinyon-juniper woodlands are common.

Pinyon and juniper trees have spread into adjacent sagebrush ranges and have depleted the understory in these areas as well. Referred to as "asbestos forests," the pinyon-juniper woodlands lack the fine fuels to keep a fire contained under moderate conditions. When a fire does get started, weather conditions are so severe that the results are catastrophic.

After the burns, expansive areas are exposed to invasion by cheatgrass and other noxious weeds. Once the conversion is made to cheatgrass, the natural process to reestablish the former native plant communities can take decades, if it takes place at all. These areas provide limited value to the remaining wildlife and are guaranteed to burn more often.

High-risk homes

If catastrophic wildfires burning up livestock grazing land and wildlife habitat aren't enough to put rangelands high on our list of concerns, then perhaps the possibility of entire subdivisions going up in smoke will.

Western range fires have been increasing in intensity for years, but because there are more homes in the woods now, we're starting to take notice. When homes are in the path of a major wildfire, the response to put those fires out is more aggressive, more costly and more hazardous to those fighting the fire on the ground and in the air.

News reporters do the lead story in yellow fire shirts and hard hats, and they've done a good job of introducing you to cheatgrass, the little annual grass behind the problems you're seeing. Now you know even more about the culprit they've introduced you to.