Restoring the Sagebrush Sea, One Carbon-coated Seed at a Time

This article was originally published in The Midden – Great Basin National Park: Vol. 23, No. 2, Winter 2023.

NPS Veg Crew member M. Gardner applying blue-dyed herbicide to test plots.

NPS Photo/Dani Ruais

By Dani Ruais, Biological Science Technician

When driving through the seemingly boundless Great Basin ecoregion, you may notice the patches of silvery-green shrubs that blur into each other to form a gently rolling ocean. This sagebrush steppe ecosystem is lovingly dubbed the “Sagebrush Sea.” This area may not look like important habitat for animals, insects, and other lifeforms that belong here, but it, and those dependent on it, have been steadily declining for decades.

The combination of overgrazing, development, climate change and the Euro-centric custom of fire suppression has drastically altered this once intact system of sagebrush and native grasses and forbs. Overgrazing and other stressors have depleted the topsoil and allowed for the invasion of non-native annual grasses such as cheatgrass (Bromus tectorum L.)— introduced to the USA from Eurasia in the 1800s—to spring up, spread, and degrade native ecosystems. Cheatgrass has invaded all 50 US states, including Alaska and Hawaii.

Natural fires and frequent, intentional fires set by Great Basin’s Indigenous peoples allowed the land to undergo regeneration on a more regular basis (every 60—100 years). Since the widespread invasion of cheatgrass, wildfires get out-of-hand quickly, often burning too hot, too fast, and too intensely for the vegetation and the land to benefit. Scientists call out cheatgrass and other invasive annual grasses as some of the “primary threats” to the sagebrush sea and all those sustained by it.

So how do we help restore sagebrush and maintain biodiversity? The short answer: It takes a team! Great Basin National Park’s vegetation crew teamed up with researchers from the USDA’s Agricultural Resource Service (ARS) out of Burns, Oregon, and The Nature Conservancy to test a possible solution: revegetate areas of the sagebrush steppe with native perennial bunchgrasses that can outcompete invasive grasses.

Active carbon-coated bluebunch wheatgrass seeds.

NPS Photo/Dani Ruais

One of the current methods to control cheatgrass is to use the herbicide Imazapic to prevent invasive annual grass seeds from germinating. About a year after applying the herbicide, native plant seed can be sown onto the same area without negative effects to the new, native seeds. However, revisiting the site two years in a row costs time and money. And, by that time, a new crop of cheatgrass may have already seeded and started to germinate. Invasive annual grasses are extremely fast growers; quickly outpacing and outcompeting the native grasses. Cheatgrass can also squeeze in more growing cycles and set more seed while also being prime fuel for wildfires.

To remedy this dilemma, federal institutions have partnered with private companies to create specialized seed coatings that physically cover and protect the native bunchgrass seeds. Now, instead of a two-step process that involves a wait time of a year between steps, these seeds, with their fancy little coats, can be sown in a chosen area and then sprayed with this herbicide—right over the top—and their growth will not be adversely affected.

This type of seed coating technology uses activated carbon for its high absorption capability which deactivates many herbicides. In the picture, you can see bluebunch wheatgrass seeds (Pseudoroegneria spicata)—a bunchgrass native to the Great Basin —which have been coated with activated carbon.

Test plots are sprayed with a blue-dyed herbicide.

NPS Photo/Dani Ruais

The ARS research team lab-tested the coated seed and it performed well: germinating and growing after being sprayed with Imazapic. The next phase was to set up field trials across a range of cold desert sagebrush steppe sites. Great Basin National Park hosted two sites for the field trial. The sites within the park’s boundaries were areas with exposed soil, and minimal shrub and tree cover.

The research team measured out a control and experimental plot at each site. Then they were seeded and covered with a layer of fine-sifted, sterile soil. Next, the Park’s Vegetation Crew used a manual backpack sprayer to lay down a 1-meter-wide spray swath of herbicide mixed with blue dye.

Researchers from ARS will return to the Park to monitor the plots and record data in May 2024. Hopefully the field trials will prove as successful as the lab studies, giving land managers a new tool to control invasive annual grasses and help restore the Sagebrush Sea.

References
Davies, K. W., Leger, E. A., Boyd, C. S., & Hallett, L. M. (2021). Living with exotic annual grasses in the sagebrush ecosystem. Journal of Environmental Management, 288, 112417. https://doi.org/10.1016/j.jenvman.2021.112417

Davies, K. W., Madsen, M. D., & Hulet, A. (2017). Using Activated Carbon to Limit Herbicide Effects to Seeded Bunchgrass When Revegetating Annual Grass-Invaded Rangelands. Rangeland Ecology & Management, 70(5), 604–608. https://doi.org/10.1016/j.rama.2017.04.004

*Holfus, C. M., Rios, R. C., Boyd, C. S., & Mata-González, R. (2021). Preemergent Herbicide Protection Seed Coating: A Promising New Restoration Tool. Rangeland Ecology & Management, 76, 95–99. https://doi.org/10.1016/j.rama.2021.02.005

Madsen, M. D., Davies, K. W., Mummey, D. L., & Svejcar, T. J. (2014). Improving Restoration of Exotic Annual Grass-Invaded Rangelands Through Activated Carbon Seed Enhancement Technologies. Rangeland Ecology & Management, 67(1), 61–67. https://doi.org/10.2111/rem-d-13-00050.1

Reed-Dustin, C. M., Mata-González, R., & Rodhouse, T. J. (2016). Long-Term Fire Effects on Native and Invasive Grasses in Protected Area Sagebrush Steppe. Rangeland Ecology & Management, 69(4), 257–264. https://doi.org/10.1016/j.rama.2016.03.001

*The Holfus et al. paper above is the paper published by the ARS researchers doing this study in the park.