Master of Environmental Science and Management: Master's Group Project
Conservation of Yellow Pine Mixed Conifer Forests in Southern California National Forests
US Forest Service
Fire suppression policies have led to changes in forest structure throughout California, which increases the risk of stand-replacing fires. Additionally, vegetation in California is expected to move towards higher elevations due to climate change. Understanding these shifts in forest structure is important for future resilience. To accomplish this we (1) compared changes in forest structure in yellow pine mixed conifer (YPMC) forests in Southern California over the last century and (2) created a MaxEnt model to understand the range shifts of yellow pines in the Transverse Ranges. We found significant increases in tree density, canopy cover, and basal area across Southern California YPMC forests. This change is primarily due to an increase in large diameter trees (61-91.3cm) and an increase in shade tolerant trees. Quercus chrysolepis has particularly increased at lower elevations, while conifer juveniles have decreased across these elevations. These results indicate a potential composition shift from conifer forests to oak dominated systems. Our MaxEnt model demonstrates that under climate change, suitable habitat for yellow pine saplings is shrinking across the Transverse Ranges. Our project will assist the USFS in creating targeted management goals in selecting high priority areas for the conservation of Southern California YPMC forests.
USFS: Gabrielle Bohlman, Associate Ecologist; Sarah Hennessy, Ecologist
Bren School: Frank Davis, Professor; Allison Horst, Lecturer; Ashley Larson, Assistant Professor