Hidden threat: How non-native plants fuel wildfires, degrade ecosystems

Invasive grasses have also wreaked havoc on the threatened Oregon spotted frog. Efforts are underway to save its habitat

By Sue Kusch. October 1, 2020. Many of us drive through the open rangelands of the Columbia River Basin on our way to somewhere else. The honey-colored dried grasses that blanket the midsummer landscape appear innocuous as they sway in the wind.

What we don’t see is the potential of the vast swaths of dried grass to explode into a fast-moving and volatile grass wildfire that blackens the land, eliminates native plant vegetation and destroys rural economies.

One of the biggest invasive species problems in the United States, cheatgrass has taken root in every state and dominates over 50 million acres of western grassland and sagebrush steppe habitat.

In the last 20 years, an increased number of wildfires on cheatgrass-infested lands is proving to be the most damaging of its many negative consequences.

Cheatgrass blooms early in the wet spring and dries out by June, forming a thick thatch similar to our green suburban lawns. This dried thatch becomes both tinder and a sustained fuel base for wildfire, extending the natural fire season by months.

“Basically cheatgrass is comparable to tissue paper covering the landscape—an easily ignited fuel that carries fire quickly and spreads it rapidly,” says Mike Pellent, retired Bureau of Land Management (BLM) rangeland ecologist.

[perfectpullquote align=”full” bordertop=”false” cite=”” link=”” color=”” class=”” size=””]Cheatgrass’s ability to dominate land has essentially created millions of acres of wasteland.[/perfectpullquote]

Once a grassland fire has occurred, cheatgrass moves onto the disturbed soil, utilizing nitrogen in the soil, creating a vicious cycle.

“Wildfires promote more cheatgrass, which in turn further increases the impacts and probability of wildfires,” says Pellent.

While forest fires receive media attention and are given far more resources than rangelands, the reality is that since the year 2000 more acres of grasslands have burned than forests.

Fast-moving wildfire destroys the rural infrastructure used to maintain the ranching economy: fencing, water troughs, cultivated hayfields and cattle are repeatedly destroyed by wildfires that now occur every three to five years.

How the invaders invaded

Native to Europe and East Asia, cheatgrass (Bromus tectorum), like many non-native plants, sailed across the Atlantic from Europe mixed in with straw and grain sent to support North American settlers’ introduction of cattle in the mid-to-late 1800s. Railroads enabled the grass seed to continue west where it thrived on grassland denuded by the introduced livestock.

Adapting to the cold, wet winters and hot, dry summers of the Great Basin and Columbia River Basin, cheatgrass found an inviting landscape throughout western rangelands. It’s particularly aggressive in the sagebrush steppe ecosystem where it has earned the designation of a noxious weed, dominating the land to the exclusion of all other plants.

Beyond wildfires, the environmental and economic impacts of cheatgrass invasion are significant and long-lasting. Eliminating native vegetation like sagebrush and Idaho fescue alters the evolved relationships between plants and animals, affecting 350 species that depend on the sagebrush habitat for food, protective cover and nesting.

Cheatgrass’s ability to dominate land has essentially created millions of acres of wasteland. The loss of native flora and fauna and the threat of wildfire greatly diminishes the ability of people to use the land not only for grazing but for recreational activities such as hunting, birding and hiking.

Efforts to contain it cost government at all levels millions of dollars a year.

Threatening Oregon spotted frogs

In the wetter landscapes of the Pacific Northwest, another non-native grass is altering wetland ecosystems, using its aggressive rhizomes to quickly create monocultures around the edges of ponds, lakes and streams.

Reed canary grass (Pharlaris arundinacea) is a perennial grass that was initially introduced as highly productive forage on pastureland.

Eventually, the grass escaped pastures, thriving in nutrient-rich riparian environments scattered throughout the Pacific Northwest.

Unlike the short-stemmed cheatgrass, reed canary grass grows six-foot stems that tower over the edges of wetlands while simultaneously developing a thick mat of roots that encourages the accumulation of sediments, inhibiting the growth of native vegetation. Its annual production and release of wind-blown seeds contribute significantly to the spread of this grass.

“Reed canary grass can dominate seasonally wet meadows, which creates large areas of dense, coarse vegetation that limit feeding options for the Sandhill cranes and other ground nesting birds that prefer to feed in short vegetation,” says Keyna Bugner, natural areas manager for the Washington Department of Natural Resources, Southeast Region. “In addition, the tall grasses make it difficult for the birds to travel through, and also provide cover from predators that could harm the Sandhill cranes and their young during the vulnerable time before the young are able to fly.”

One of the contributing factors in the decline of the federally listed threatened Oregon spotted frog, reed canary grass alters the native habitat necessary to the frog’s reproduction. The red-bellied frogs lay egg masses among short grasses in the open and un-shaded low water levels of ponds.

For several years, a joint effort by federal and state agencies has been underway to restore habitat for the Oregon spotted frog at the Trout Lake Natural Area Preserve in the Columbia River Gorge.

The removal of reed canary grass is key to the success of the project. Bugner employs a variety of removal methods: hand pulling, herbicides, mowing and solarization, which involves placing heavy, black weed cloths on the invasive grass to kill it. When the cloths are removed several years later, the bare ground is planted with native plants endemic to the area.

Re-establishing native plant species is critical to the success of restoration projects.

“Using locally sourced plants and seed from your project area will greatly increase the success of re-establishing native vegetation,” says Bugner.

Fighting invasive plants

One of the challenges in managing invasive plant species is fragmented ownership of land. State and federal agencies have partnered with private landowners, creating plans to jointly manage invasive species.

The Sage Grouse Initiative is one example of the many partnerships created to coordinate efforts for the eradication of invasive species and the restoration of native habitat.

This can appear to be an overwhelming problem, best left to professionals. But Greg Peters of the Sage Grouse Initiative, and DNR’s Bugner, offer the following recommendations to individuals and property owners who can help deal with the problem:

• Monitor and eradicate invasive plants regularly

• Plant and maintain native plants to prevent invasive plants from taking hold

• Limit disturbance of native ecosystems

• Avoid bringing fire to grasslands—campfires, cigarettes, fireworks, ATV travel—during the driest time of the year

• Become informed and volunteer with local organizations working on restoration projects

Invasive non-native plant species are wreaking havoc on many of our native ecosystems. After an invasive species has been introduced, it becomes a time-consuming and expensive problem to manage. Prevention is the best way to manage invasive species.

A former college educator and adviser in Vancouver, Washington, Sue Kusch cultivates edible, medicinal and native plants. She currently serves as president of the Suksdorfia Chapter of the Washington Native Plant Society.