Undergraduate Research Conference Proceedings

Coastal sage scrub (CSS) ecosystems are home to hundreds of bird and insect species. Their range has been significantly reduced, so restoration is crucial. Unfortunately, CSS plants in North Campus Open Space struggle at the Audubon Overlook, yet they thrive on South Parcel. California sagebrush (Artemisia californica) is a foundation species in CSS ecosystems, and these plants grow best in sandy, well-draining soils. Previous researchers hypothesized that high soil compaction stunts CSS plant growth, but more research is needed on how soil bulk density and texture may affect California sagebrush. Our first hypothesis was that California sagebrush responds negatively to high soil bulk density in clay soils but not in sandy soils. Our second hypothesis was that California sagebrush are larger and CSS plants are more abundant on South Parcel due to sandier soils. We measured the dimensions of California sagebrush closest to soil bulk density locations at the Audubon Overlook and South Parcel, and we counted CSS plants in a 3 meter radius of each location. We also analyzed soil texture for 6 Audubon Overlook locations and 10 South Parcel locations. We didn’t find a significant difference in California sagebrush volume within the Audubon Overlook based on soil bulk density. However, the mean soil bulk density was higher at the Audubon Overlook, and the median California sagebrush volume, median number of living California sagebrush in a 3 meter radius, and median number of living CSS plants in a 3 meter radius were all higher for South Parcel; these differences were statistically significant. Also, the sand content was higher for the South Parcel locations. This suggests that soil bulk density relative to soil texture might affect the growth and abundance of CSS plants. This research and future research may inform coastal sage scrub restoration.