Restoring the Sagebrush Sea With Carbon-Coated Seeds

Drive across the Great Basin and you'll see silvery-green shrubs rolling away like waves — the sagebrush steppe, nicknamed the "Sagebrush Sea." It may not look like prime habitat, but it supports many animals, insects and plants, and it and the life it sustains have been declining for decades. Dani Ruais, a biological science technician at Great Basin National Park, described a new approach to restoring it in the park's newsletter, The Midden (Winter 2023).

Park vegetation crew member M. Gardner applies blue-dyed herbicide to test plots. NPS photo / Dani Ruais.

The cheatgrass problem

Overgrazing, development, climate change and the suppression of fire have transformed what was once intact sagebrush with native grasses and wildflowers. Overgrazing and other stresses depleted the topsoil and opened the way for invasive annual grasses such as cheatgrass (Bromus tectorum), brought from Eurasia in the 1800s and now found in all 50 states, Alaska and Hawaii included.

Natural fires, and frequent fires set by the Great Basin's Indigenous peoples, once renewed the land every 60 to 100 years. Since cheatgrass took hold, wildfires run out of control, burning too hot and fast for the land to benefit. Scientists name cheatgrass and other invasive annual grasses among the primary threats to the Sagebrush Sea.

A two-step problem

One remedy is to replant with native perennial bunchgrasses that can outcompete invaders. Today, crews spray the herbicide Imazapic to stop invasive seeds from sprouting, then wait about a year before sowing native seed so the herbicide won't harm it. Two visits cost time and money — and by then a new crop of fast-growing cheatgrass may already have seeded. Cheatgrass also fits in more growing cycles, sets more seed and makes prime wildfire fuel.

A seed with a coat

Federal agencies and private companies have developed seed coatings of activated carbon, which soaks up and deactivates many herbicides. Coated native seed can be sown and then sprayed with herbicide right over the top, in one step, without harm.

Bluebunch wheatgrass seeds coated with activated carbon. NPS photo / Dani Ruais.

In the lab, researchers from the USDA's Agricultural Research Service in Burns, Oregon, found coated seed of bluebunch wheatgrass (Pseudoroegneria spicata), a native Great Basin bunchgrass, germinated and grew well after being sprayed with Imazapic.

Field trials in the park

The next step was field trials across cold-desert sagebrush sites, with the park's vegetation crew, ARS researchers and The Nature Conservancy. Great Basin National Park hosted two sites, on bare soil with little shrub or tree cover.

1. Researchers laid out a control plot and an experimental plot at each site.
2. The plots were seeded and covered with fine, sterile soil.
3. The park's crew sprayed a 1-meter-wide swath of herbicide, dyed blue to show coverage, with backpack sprayers.

Test plots sprayed with blue-dyed herbicide. NPS photo / Dani Ruais.

ARS researchers planned to return in May 2024 to measure results. If the field trials match the lab, land managers will have a new tool against invasive annual grasses — and a better chance of restoring the Sagebrush Sea.

Sources

Based on "Restoring the Sagebrush Sea, One Carbon-coated Seed at a Time," by Dani Ruais, The Midden, Great Basin National Park, National Park Service; a work of the United States government in the public domain.