“The Effects of Conifer Encroachment on an Eastern Sierra Nevada Aspen Population”

Prof. Stephens is a professor in the Department of Environmental Science, Policy, and Management, College of Natural Resources, UC Berkeley

Aspen support a unique and diverse ecosystem in Sierra Nevada forests due to their highly edible foliage and herbaceous understory. Many aspen stands in the Sierra Nevada are currently in decline due to conifer encroachment, as aspen are typically early successional species.  This study assesses the relationship between total live conifer basal area and dead aspen basal area to determine the impact of conifer encroachment on aspen survival. In addition, this study examines the relationship between conifer basal area, surface fuel loads, and shrub/herb cover to ascertain the impact of conifer encroachment on understory dynamics. Vegetation measurements were made in 23 plots in mixed conifer/aspen forest in the Eastern Sierra Nevada and analyzed using R, Strata and Excel. Results show a significant positive relationship between live conifer basal area and dead aspen basal area (p = 0.027).  This finding indicates that conifer encroachment may threaten the persistence and regeneration of Eastern Sierra Nevada aspen, and that restoration treatments, such as selective conifer removal, may revitalize aspen populations.

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Stephanie is a Geology major at UC Santa Cruz . She attended Skyline College where she received her Associate in Arts degrees with High Honors in Liberal Arts and Dance, and holds a current GPA of 3.92. Stephanie plans to transfer to the University of California, Berkeley in Fall 2010 with a major in Geology. She would ultimately like to pursue a career that involves field research investigating natural phenomena, natural resource management and conservation sciences in the broader field of Geology. Stephanie is the first person in her family to attend college.