Get to know INSTAAR’s 2025 summer scholars
INSTAAR 2025 summer scholars Harry Allbrook (left) and Hunter Geist-Sanchez. Photos courtesy of Harry Allbrook and Hunter Geist-Sanchez.
Each year, INSTAAR selects two graduate students for the INSTAAR summer scholarship, which provides funding for ongoing research over the summer months. These scholars are engaged in multi-year research efforts in the Earth sciences, and the scholarship amplifies their ability to produce high-impact, rigorous work.
In 2025, PhD students Harry Allbrook and Hunter Geist-Sanchez were awarded the scholarship. Allbrook studies marine microbial communities in Julio ú岹’s lab. Geist-Sanchez is a restoration ecologist studying plant communities from a rangeland management perspective under Katharine Suding.
This week, INSTAAR sat down with Allbrook and Geist-Sanchez to discuss their summer plans.
What are you working on this summer?
Harry Allbrook: I’m analyzing data from semi-controlled mesocosm experiments, where we simulate marine environments within an enclosed space. In particular, I’m exposing marine microbial communities to environmental stressors by manipulating oxygen, PH and nutrient levels, and seeing how they respond.
This summer, I will transform raw measurements (from liquid chromatography mass spectrometry analyses) into lists of molecular identities using open-source analytical methods. This will allow me to investigate the phenomenon of “lipid remodeling” in these mesocosms, whereby microbes adapt their cell membranes in response to environmental stress.
Microbial membranes serve as a source of nutrition for higher trophic organisms, like the fish essential to marine fisheries and indigenous communities. They also serve as fingerprints of ecosystem health, which are preserved in geologic sediments for thousands of years.
Hunter Geist-Sanchez: I’m managing two research projects. In the first, I’m hoping to identify plant species that can improve rangeland restoration efforts. Specifically, I’m testing whether certain species are more successful in bare ground interspaces within semi-arid and arid rangelands along the Front Range. If we can identify species with traits that promote establishment in these bare areas, we may be able to reverse ongoing degradation in these systems and instead promote vegetation recovery.
The second project is a long-term drought study, now in its eighth year, which stems from a partnership with the international and . In this study, we are manipulating precipitation to simulate extreme drought and excess rainfall, respectively. We also incorporate seasonal livestock grazing. The goal is to better understand the interactions between drought, excess precipitation and grazing on plant life.
Rangelands make up about one-third of terrestrial ecosystems in the U.S. and provide vital services, such as food, clean water and outdoor recreation. Climate change is increasing temperature and precipitation variability, which makes understanding these dynamics critical to preserving the ecological, cultural, and economic value of these systems.
Suding lab members set up equipment at a research site for Drought-Net in South 91PORN. From left: Hunter Geist-Sanchez, Sam Ahler, Sarah Elizabeth Stockman and Tom Merchant. Photo courtesy of Hunter Geist-Sanchez.
Harry Allbrook loads equipment aboard the German research vessel RV Sonne in the Port of Talcahuano in Chile. Photo courtesy of Harry Allbrook.
How will the summer scholarship support this work?
Harry Allbrook: The scholarship will enable me to complete a vital step in my thesis project. I’m also looking forward to developing educational outreach tools (“microcosm in a mason jar”) that enhance ocean literacy and share my team's work with middle-school students.
Hunter Geist Sanchez: With my summer funding covered by the scholarship, I’m able to use other grant funds to hire undergraduate research assistants and purchase essential equipment. This includes soil temperature and moisture sensors as well as soil nutrient testing tools to assess how drought conditions affect nutrients in the soil.
I’ve hired two current CU undergraduates and a 2025 CU graduate to assist with both projects. They will get hands-on experience in ecological research, preparing them for a career in rangeland health and management.
What do you like to do when you’re not doing research?
Harry Allbrook: When I'm not doing research, I love to rock climb, cook, collect vinyl records (particularly electronic music) and paint with watercolors!
Hunter Geist-Sanchez: Outside of research, I enjoy spending time with my family and friends, hiking and doing other outdoor activities, cooking, and traveling!
To support INSTAAR's summer scholarship for graduate students, .
If you have questions about this story, or would like to reach out to INSTAAR for further comment, you can contact Senior Communications Specialist Gabe Allen atgabriel.allen@colorado.edu.