Student Research Update: Leonie Casper '25
Leonie presented a poster on isotopic work at the Ecological Society of America Conference in Long Beach
For two years, Leonie Casper has been balancing the demands of an intensive ecological research project with all the conventional extracurricular activities of a talented SCU student. She capped her academic achievements by giving a solo talk at a scientific conference.
Leonie’s research has been into water-use efficiency, a component of drought tolerance, in woody plants. Along with fellow researcher Trey Grimsley ’24 (now in grad school at the University of Georgia), she has deeply explored this physiological mechanism in eleven species of trees and shrubs that are commonly planted in riparian areas, or riverbanks, in California habitat restoration projects. The work is funded through the nonprofit River Partners, which has restored thousands of acres of native floodplain forest along California’s rivers.
“Drought conditions are becoming more extreme in California due to climate change. We want to know if there are any species that are particularly suited to resisting lower water availability among these ones that River Partners plants, as this information would help inform the sustainability and long-term viability of future restoration efforts,” said Leonie.
The first phase of the research involved two weeks of difficult field work in the Sacramento Valley, enduring temperatures as high as 120°F, as Leonie and Trey needed to measure photosynthesis and transpiration at midday. The balance between how much carbon the plant gains in photosynthesis versus the water it loses in transpiration is the basis for water-use efficiency.
The team learned to use an arborist’s line launcher, aka “the giant slingshot,” to bring down branches from the 20+ meter canopy for gas analysis. After the fieldwork was through, Leonie painstakingly ground the dried leaves and meticulously filled foil capsules with the leaf powder for analysis on a mass spectrometer. The isotopic composition of these leaves is another indicator of water-use efficiency.
Finally, a third experiment in the greenhouse, which involved 10 research assistants carefully measuring every drop of water consumed by the riparian species while growing in pots, gave Leonie a second dataset with which to analyze water-use efficiency. Combined with Trey’s analysis of the gas-exchange data from the fieldwork, the team now has a very nuanced picture of the relative water-use efficiency of all these species.
In April Leonie and her mentor, Dr. Virginia Matzek, traveled to Sacramento for the California Society for Ecological Restoration conference, and Leonie covered all three analyses in a solo conference talk. (Previously, she and Trey had presented the earlier experiments as individual posters at the Ecological Society of America meetings in August 2024.) The work recommends to River Partners that, where ecologically appropriate, plantings emphasize the most water-use efficient shade-tolerant canopy trees, such as box elder, sycamore, and Oregon ash.
In addition to her scientific work in the Matzek Lab, Leonie is active in the SCU Chamber Singers ensemble, where she sings soprano, and is a devotee of the Books and Tea Club that meets weekly in the library for tea and literary discussions. An honors student from Claremont, California, Leonie maintains a 3.885 GPA and was recently inducted into Alpha Sigma Nu, the Jesuit Honors Society. Her research will constitute her honors thesis, and she will also be a co-author, along with Trey and Dr. Matzek, on the eventual publication.
Photo caption: Leonie Casper ’25 at her first conference presentation. She gave a poster on the isotopic work at the Ecological Society of America conference in Long Beach last year.
Video caption: Trey Grimsley ’24 and Leonie Casper ’25 bring down a branch from the canopy for analysis of gas exchange.