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Where the bison wallow

Where the bison wallow

Thirty miles southwest of FLC’s campus in Durango, bison roam over rolling hills covered in rabbit brush and sage. Thick stands of piñon and cedar and unruly mobs of gambel oak reach toward the La Plata Mountains on the northern horizon and south toward New Mexico’s sprawling mesas. But the Gleason Bison Ranch is more than a sight to behold; it’s the location of senior seminar research projects for two FLC students, Abrianna Bennett and Trevor Lomaomvaya.

Five hundred years ago, bison passed freely and frequently across this land where Bennett and Lomaomvaya’s study takes place. The prairie was home to dozens of grass species, while the understory would burn in wildfires roughly every 20 years. However, over the past 150 years, wildfires have been suppressed, and bison have been replaced with cattle. As land management practices have altered over the years, conditions have emerged that allow certain species to thrive, while making it harder for other species to even survive. For instance, the piñon and juniper stands have grown denser, rabbit brush and sage have taken over, and thick masses of gambel oak encroach on the open spaces. In some places, the ground is bare, exposing clay-rich soils that shed water rather than absorb it. Once plants are removed from soil like this, it’s difficult for grasses to get reestablished. This then impacts the ability of the soil to retain water, and the process compounds itself.

Enter a herd of bison.

a bison wallows in the middle of a herd of bison in a prairie 

Bison are big animals, the bulls growing to over 2,000 pounds. They roll around on the ground from time to time in a kind of dustbath, kicking up sand that helps cool them off in the hot summer sun while making their skin less interesting to insects. When bison roll around on the dusty ground, their weight creates depressions in the earth, typically six to ten feet across and as much as five or six inches deep. These depressions, called bison wallows, then collect water during a storm, affecting the way water interacts with the soil. FLC students Bennett and Lomaomvaya are finding out how by measuring the way water soaks into the soil in a bison wallow, as well as the amount of carbon and nitrogen captured in that soil. They will then compare that data with an adjacent plot just outside of the wallow.

By reintroducing bison to this landscape, and allowing grasses to grow back between grazing seasons, Gleason Bison Ranch owner and operator Sarah Gleason aims to weave food production and land conservation together in a single effort, rather than disparate or even competing efforts. She looks at the land as a whole system, monitoring and supporting life and growth from soil bacteria and microinvertebrates, to the 70 species of birds on the Audubon-certified ranch. Her approach not only demonstrates how to make ranching easier, more productive, and more profitable, but also reflects one way to reestablish a sustainable food system in the Four Corners.

Gleason hasn’t always been a rancher, and her transition into ranch life hasn’t always been easy, but her sincere love of the natural world and her deep appreciation for the power of relationships have made for a strong start. After working in marketing and public relations for ten years, Gleason decided she wanted to work outside. She began talking with her husband, Mike, about ranching when he asked, “What about bison?”

Sarah Gleason leans on a truck amongst a herd of bison.
Sarah Gleason, owner of Gleason Bison Ranch, leans against her truck as she describes the role of bison in shortgrass prairie ecosystems.

In 2012, Gleason joined the National Bison Association and began visiting ranches and learning about the animals. In 2015, she started working with the Savory Institute, where she learned about regenerative agriculture and holistic planned grazing, an approach to ranching that is adaptive in nature, and relies on continuous experimentation and monitoring. One year later, she bought her first 15 bison cows (female bison, not to be confused with cattle). In 2020, Gleason brought her herd to Breen, Colorado, to live on land leased from Tom and Penny Compton.

The Comptons’ daughter, Leann Harbison, is a professor of Biology at FLC. Harbison introduced Gleason to another FLC Biology professor, Heidi Steltzer, with whom Gleason began brainstorming potential research projects. Steltzer put it to her students to find out what interested them. Lomaomvaya and Bennett jumped at the opportunity to study bison wallows, which could open their worlds to exploring not only the impacts of human land management but to also better understand the history of their families and communities.

For Texas-raised Bennett, agriculture is at her community’s core. A Tribal Member of the Caddo Nation in Oklahoma, Bennett says she sees herself first and last as Texan. While she’s not much for walking through snow to class in Durango, she is excited to be learning things she can bring back to her home community. At the top of that list is how to talk science with people who aren’t scientists. When she approaches a rancher, she tries to think how they think: “I know this is how you feed your family, and with what we know through science, how can we help feed future generations, too?”

“It’s important to be able to relate to someone first so we know how to get the science across in a way that’s meaningful to them,” she says. “I think that too often we just throw science at people, and I don’t think anyone likes having science thrown at them.”

Trevor Lomaomvaya and Abrianna Bennett collect soil samples for their bison wallow study.
FLC student researchers Trevor Lomaomvaya and Abrianna Bennett collect soil samples for their bison wallow study. The soil will be shipped to Colorado State University and analyzed for carbon and nitrogen.

Like Bennett, Lomaomvaya is a fanatical scientist. From hydrology to geology, he enjoys examining natural processes. For the bison wallow study, his scientific mind and worldview merge. As a member of the Hopi Tribe, he points out that his culture reveres bison as a symbol of moisture and strength.

“Where I grew up, it’s semi-arid, desert-like,” says Lomaomvaya, who is from the Hopi Reservation in Arizona. “For a long time, we sustained ourselves with agriculture, raising drought-tolerant crops. In the 1600s, livestock were introduced to the Hopi by the Spanish. In the 1950's, my great-grandfather started cattle ranching as his livelihood after selling his uncle’s sheep flock. My dad was given a calf when he was 12 and also went into cattle ranching. The drought had gotten pretty severe by 2004, and there wasn’t enough moisture to sustain the cattle, so my dad sold all his cattle.”

Through the bison wallow study, Bennett and Lomaomvaya hope to understand how reintroducing native bison to the land could support ecosystem restoration and potentially improve drought resilience so other ranchers, like Gleason, don’t have to follow the same fate as Lomaomvaya’s family.

“The more information I have, the better land manager and livestock manager I can be,” says Gleason of her partnership with FLC students. “It takes a long time to collect data—we need long-term studies. I hope to develop a lasting relationship with FLC, something where students can start doing research as sophomores, on projects that extend for years.”

Phase 1 Illustration of bison standing in a field.

A bison chooses a dusty site to cover itself in dirt to relieve skin irritations.

Phase 2 Illustration of bison wallowing - rolling on the ground.

The bison wallows, compacting the soil.

Phase 3 Illustration of a bison walking away from a depression in the ground.

Repeated wallowing creates a concave depression.

Phase 4 Illustration of rain falling, creating a puddle in the depression in the ground.

Rain fills the depression.

Phase 5 Illustration of grass, flowers, and other plants growing in the depression in the ground.

Compacted soils become mesic (holds water), allowing new plants and insects to thrive.

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