Completion Date
9-2025
Advisor(s)
Dena Grossenbacher
Abstract
As climate change progresses, alpine plant communities are predicted to shift upslope as they track temperature over time. Relative to lowland environments, alpine areas are experiencing a faster rate of temperature change due to a phenomenon referred to as elevation-dependent warming. A common approach for tracking plant communities shifts over time, is to conduct resurveys of the same area at several time points, as the Global Observational Research Initiative in Alpine Environments (GLORIA) has done on mountain summits around the world since 2001. In 2011-2013, GLORIA developed a supplemental survey method whereby belt transects were established downslope of summits in order to detect elevation-based changes within a mountain slope. Initially, they established belt transects across five alpine slopes in the Great Basin region of California, providing insights into community turnover in water-limited alpine environments. However, they have yet to establish transects in less water-limited alpine areas, such as the west slope of the Sierra Nevada. Here we fill this gap, by establishing 41 transects on four Sierran alpine slopes in Yosemite National Park in 2023-2025 (Figure 1). At each site, a series of 100-meter belt transects are situated 25-vertical meters apart on southwest-facing slopes, extending from treeline to ridgeline. Each transect is split into 5-meter segments surveyed by identifying all species and completing point-intercept surveys. In addition to these baseline trends, we also explored inter-observer error whereby species are misidentified or missed altogether, leading to differences between surveys due to observers rather than species turnover. To quantify inter-observer error, we surveyed a subset of 115 segments (Figure 2) with two observer teams on the same day, and compared their species lists using the Sorensen dissimilarity index. In 2023, Rachel Friesen and a crew of four undergraduate students established 12 transects on Mt. Dana (see 2023 Baker-Koob Award Report). In 2024, Brooke Wallasch, (one of the original undergraduate students on Friesen’s crew) started her master’s project focused on expanding this vegetation monitoring effort to three other peaks in Yosemite National Park. From April to June 2024, Wallasch trained four undergraduate students (Ty Connelly, Julian Durante, Emily Staats and Marjorie Say) in backcountry safety and vegetation monitoring protocols. Wallasch and her crew established 10 of these transects on Mt. Lewis and 9 in the Gaylor Lakes Basin. During the last two weeks of the field season, these students volunteered with Yosemite National Park Service Staff where they completed vegetation surveys using additional samping protocols and participated in restoration efforts. This opportunity provided a unique opportunity to network with National Park Service staff while gaining valuable hands-on field work experience. In April 2025, Wallasch trained a new crew of three undegraduate students (Annalise Burrows, Madeleine Colbert and Michael Gottlieb). During the first week of the field season, Wallasch and her crew volunteered with the Great Basin chapter of the Global Observation Research Initiative in Alpine Environments (GLORIA) to complete vegetation surveys on White Mountain Peak and other nearby peaks in the Inyo National Forest. This event brought together many botanists from a diverse set of careers which offered a fruitful networking opportunity. During this event, Annalise Burrows connected with botanist Dylan Neubauer who shared her insights regarding Castilleja hybridization in the White Mountain area, which has since led Annalise to pursue this topic for her senior project at Cal Poly San Luis Obispo. From the July 29th to August 8th, Wallasch and her crew established 10 more transects on Mt. Gibbs. During these surveys, Annalise, Madeleine and Michael noticed that many of the cushion-like alpine plant species were in poor health. To quantify their observations, they identified a research question, developed a sampling protocol, collected data, analyzed the data using R, and communicated their results in an oral presentation as part of the 2025 Frost Summer Undergraduate Research Program Symposium at Cal Poly San Luis Obispo, allowing these students to fully engage in the scientific process. To finalize this project, Wallasch cleaned and analyzed the data, culminating in her master’s thesis which she defended on September 11, 2025. The results showed that community composition was similar across all four sites with similar species appearing in high abundance, and 36-60% of variation in species composition explained by elevation at each site. Inter-observer error was higher on Mt. Dana (20%) than Mt. Lewis (10%) and increases with higher vegetation cover at both sites. The establishment of these 41 transects marks the beginning of a long-term vegetation monitoring data set. These transects will be resurveyed every 5 years with continued collaboration between Cal Poly San Luis Obispo and the National Parks Service, strengthening this partnership and offering future opportunities for undergraduate field work and research. The information acquired in this study will inform future hypotheses related to this longterm data set. The legacy of this project will provide data that will help National Park staff to make informed management decisions when conserving alpine communities and will inform interpretations of change over time for decades to come.
URL: https://digitalcommons.calpoly.edu/bkendowments/118
Copyright
This work is licensed under a Creative Commons Attribution 4.0 International License.