Cheatgrass and Japanese Brome: Fighting Invasive Grasses in Northern Great Plains Parks

National parks aim for healthy, natural ecosystems full of plants and animals native to the region. Invasive species — non-native plants or animals that crowd out natives for limited resources — work against that. In the grasslands of the northern Great Plains and the Intermountain West, two annual grasses from Europe and Asia are a particular problem: cheatgrass (Bromus tectorum) and Japanese brome (Bromus japonicus).

Data gathered over 23 years in northern Great Plains parks show these annual bromes make up as much as 30% of the plant community in some parks.

How bromes cheat

Good grassland packs many native species into a small space. Annual bromes "cheat" by using up soil moisture and nutrients early in the year, before native plants sprout; each plant can make hundreds of seeds. Because they grow and die earlier than most grasses, invaded patches show up brown in green summer grassland.

The harm spreads:

• they displace plants that pollinators — bumble bees, butterflies, beetles — depend on, with knock-on effects up the food chain;
• they're poor forage, with little digestible material, and their sharp dry seeds can cause sores in the mouths and on the feet of mammals.

Measuring grass in a northern Great Plains park. Image from the NPS page on invasive grasses

Adaptive management

Natural processes — grazing by wildlife and fire — are the preferred controls, but often aren't enough. With the U.S. Geological Survey, the Park Service built the Annual Brome Adaptive Management (ABAM) framework to help managers use "real-time" data and science for cost-effective decisions.

Adaptive management is learning by doing: set objectives, weigh several strategies, collect data before and after acting, and use the results to do better next time. ABAM parks use a mathematical model to predict the outcomes of prescribed fire, herbicide, or both. Controlled experiments help, but real landscapes differ in weather, plants and soils; the model accounts for that, and its predictions improve every year as results come in. It takes time, resources and coordination — but with collaboration, diverse grassland can be part of each park's future.

Parks in the Annual Brome Adaptive Management program. Image from the NPS page on invasive grasses

The participating parks include Agate Fossil Beds, Badlands, Devils Tower, Fort Laramie, Little Bighorn Battlefield and Scotts Bluff.

How you can help

Seeds caught in clothing. Image from the NPS page on invasive grasses

• Check shoes, gear, pets and vehicles for seeds, especially entering or leaving a new area; bin what you find.
• Buy weed-free hay for livestock and horses.
• Burn local firewood so you don't move plant-killing insects.
• Learn the worst invasive species at home and where you travel.
• Check whether a garden plant is invasive before you buy it.
• Support prescribed fire and learn why it matters in northern Great Plains ecosystems.

More: PlayCleanGo.

Sources

Based on "Managing Invasive Grasses at Northern Great Plains Parks," National Park Service; a work of the United States government in the public domain.