On a late summer day in a grassland south of Boulder, two CU Boulder students kneel in knee-high grass counting plants in a cordoned section of the prairie, under the watchful eyes of cows grazing outside the fenced area.

Against the backdrop of the Flatirons, graduate student Julie Larson and undergraduate Emily Koke gather information on how the vegetation is responding to rainfall and grazing manipulations on city of Boulder grasslands. Koke is one of six undergraduates assisting Larson with her project this summer.

Working closely with Boulder Open Space and Mountain Parks (OSMP), Larson seeks to understand how to keep rangeland ecosystems working in the face of climate uncertainty.

Larson is a doctoral candidate affiliated with the Department of Ecology and Evolutionary Biology (EBIO) and the Institute of Arctic and Alpine Research (INSTAAR). She works in the lab of Katharine Suding, a professor in EBIO and an INSTAAR fellow. 

This summer, Larson was awarded a predoctoral fellowship from the U.S. Department of Agriculture and the National Institute of Food and Agriculture. The two-year fellowship is awarded to doctoral students to cultivate future leaders who are able to address and solve emerging agricultural challenges. For Larson, that means taking a hard look at the challenges facing a Front Range that values open spaces and sustainability alongside local agriculture, but is also faced with a changing climate and complex management decisions.

“What scientists are doing to study and understand the implications of a changing environment cannot exist in a vacuum,” Larson said. “If our science is to lead to change, our research questions and potential solutions must be developed with all those using or connected to that environment. In the case of our local open spaces, this means talking to land managers concerned with nature conservation in an ever-changing Front Range, as well as ranchers and other agricultural operations who depend on the land for a living and are important to the cultural heritage of the Front Range.

“My bigger goal here is to make those connections and to provide the science that is needed by all land users to come together and make better decisions,” she said.

Reading leaves—and roots and seeds

Located on OSMP grasslands south of Boulder, the research site is in a habitat conservation area designated to help protect larger areas of contiguous habitat on OSMP land. An online permit is required for off-trail access, which means few visitors for Larson besides the cows and their owners from the Hogan Ranch, long-term lessees on OSMP grasslands. 

For OSMP, managing the use of open space requires careful consideration of the long-term health of some special ecosystems, even as they play a role in agriculture and recreation.

“I stress the rarity and importance of the tall grass prairie communities that are preserved in the Boulder area, in part by soils that were too rocky to plow and the preservation of open space,” said Lynn Riedel, plant ecologist for OSMP. “Better understanding of how to manage these ecologically important native grasslands using cattle grazing, along with occasional prescribed fire and various weed control methods is a high priority for OSMP.”

Cattle grazing can provide key ecological and socioeconomic benefits in open spaces, but with extreme precipitation events predicted for much of the western U.S., it’s important for land managers and ranchers to understand how and why grassland pasture systems will respond. 

Using a set of fenced-off grazing test sites and rainfall manipulations in pastures outside of Boulder, Larson is taking prediction in these plant communities to the next level. Each year, she is following thousands of individual plants and seeds that are in the soil (called the seedbank) to understand how plant species differ in their survival responses, their ability to come back from the seedbank, and ultimately, their resilience to drought under different grazing scenarios. Not all plants are created equal, and she expects to see a range of different responses. To predict these, she is looking to the root, leaf and seed traits of different species as quantitative indicators of how they will respond to grazing and rainfall.

In an area the size of a football field, Larson’s team of students helps map plant communities and collect seedbank samples from all 72 plots spread across the field. They have sketched every individual plant in these communities to see which plants might be disappearing due to drought or coming back with a good wet year, and how the seedbanks fare in different conditions. 

And for the managers and users of the land, Larson is challenged to bring all that information back together, and assess how this range of plant responses ultimately impacts the overall diversity, productivity and functioning of rangelands.

‘A perfect opportunity’

Growing up in the Midwest, Larson was fascinated with nature. Growing up with limited access to wilderness areas or day hikes, the wild was always a treat. On walks with her mom, they would stop and take about “a jillion pictures” and her mom would teach her about the plants along the way.

“Even though I found myself taking notice of the nature around me far more than others growing up, I actually had no idea what it could look like to turn that interest into a career,” Larson said. “It wasn’t until I got my first college job restoring the same forests that my mom and I used to walk in that I discovered the opportunity and the need to study these systems.”

When Larson began thinking about a master’s degree, she looked west, earning an MS from Oregon State University in 2013. Before pursuing a doctorate, she worked for three years in a research lab at Chapman University in Southern California, all the while hoping to someday work in Suding’s lab. 

“For the longest time I wanted to work with Katie (Suding),” Larson said of her mentor. “I knew who she was and wanted to work with her. When I was finally ready to do a PhD program, she was my top pick.”

On this particular day, Larson is now mentoring Koke, showing her how to collect plants in a small test plot. Having come full circle and now to be mentoring a team of students of her own, Larson finds it most rewarding.

Koke had realized last spring that she wanted to explore hands-on field research as a complement to classroom studies. While talking about research with graduate students at a biology meetup, Koke was particularly interested in Larson’s work. 

“I grew up in Kansas and liked being in the grasslands with the cattle,” Koke said. “Julie seemed very supportive of undergraduate students trying to get experience. So it was a perfect opportunity for me. I’m actually a little surprised I’m involved, because I was just a freshman.

Within weeks of meeting, Koke put together a research proposal and received an assistantship from the Undergraduate Research Opportunities Program at CU Boulder, which allows her to assist Larson on this project. And it provides a stipend.

“But I would do it without the pay, because the experience is that great,” Koke said. “Since I’ve gotten into research with this environmental focus, it’s been eye opening. It’s an important topic to be focused on with the changing world. I have no idea yet where I’m going, but I’m totally ok with that because I want to explore everything.”

An important element to Larson’s research is talking with the people who have a stake in her research, including the city of Boulder and the ranchers—many of whom have lived on the land for generations. It’s not just a question of how to deal with climate change, but how to keep agriculture going on the Front Range in a resilient way.

“I’d like to especially thank Lynn Riedel and Brian Anacker with city of Boulder Open Space and Mountain Parks, and the Front Range Livestock Association, for welcoming me in and sharing their perspective,” Larson said. “My hope is that we can continue to build these relationships between CU and the community to solve the big problems, current and future, together. It’s the role of science to help find solutions, but we couldn’t get there if land managers and ranchers didn’t open their doors and gates to have conversations about their concerns and needs.”