Available at: https://digitalcommons.calpoly.edu/theses/3034
Date of Award
6-2025
Degree Name
MS in Biological Sciences
Department/Program
Biological Sciences
College
College of Science and Mathematics
Advisor
Dena Grossenbacher
Advisor Department
Biological Sciences
Advisor College
College of Science and Mathematics
Abstract
Subalpine and alpine regions in California are warming more rapidly than lower elevations. In response, high-elevation plants may acclimate or adapt to the new climate, move to higher elevations or latitudes, persist in refugia, or go extinct. While models predict substantial declines in subalpine and alpine plant communities due to discontinuous population distributions and lack of upslope area, actual responses may vary due to lags in dispersal, establishment, and extinction. Although shifts in high-elevation plant communities have been documented in other regions of the world, such changes have not yet been studied in Yosemite National Park. To assess high-elevation plant community shifts in Yosemite National Park, we resurveyed historic vegetation plots spanning 2,800 to 3,800 meters from conifer forests to alpine fell-fields. Over the past 30 years, in the treed zone, species richness declined by 6%. In the treeless zone, vegetation cover increased by 31% and species richness increased by 12%. Community composition shifted slightly towards lower-elevation assemblages, with no significant change in community climate affinity. Notably, Pinus albicaulis appears to be transitioning from krummholz to upright growth, with 41.1% of previously alpine plots now supporting upright trees. These trends may indicate early stages of ecosystem transition under climate change.