September 1, 2016.
Overgrazing on Santa Rosa Island led to loss of topsoil in ridgeline groves of endemic island oaks (Quercus tomentella). Restoration specialists attempting to mitigate the impacts of wind and water erosion must determine efficient methods of reestablishing native vegetation. Planting pillows, burlap sacks filled with planting mix and attached to the bedrock substrate, may nurture seedlings long enough for their roots to penetrate the underlying sandstone. Since the island’s ridgeline habitat is often inaccessible during the rainy season, restoration efforts are largely confined to the dry summer months, during which condensed fog is an important source of moisture for plants. This study examined the performance of native seedlings in planting pillows under different conditions. Groups of seedlings including coyote brush (Baccharis pilularis), purple needle grass (Stipa pulchra), and yarrow (Achillea millefolium) were planted into each pillow, along with pretreated seeds of island ceanothus (Ceanothus arboreus). Seedling growth and survivorship was compared between pillows placed in the dripline of existing oak canopy, pillows fitted with fog capture structures, and pillows lacking any specific fog capture mechanism. Over a five week period, dripline seedlings demonstrated the highest growth and survivorship, seedlings planted with fog capture structures demonstrated intermediate success, and seedlings without the support of any fog capture source were the least successful.
Botany | Other Ecology and Evolutionary Biology
Kathryn McEachern, U.S. Geological Survey
California State University, Channel Islands (CSUCI)
Thanks to the Howard Hughes Medical Institute for making this research possible. Thanks to Cause Hanna, CSU Channel Islands for hosting our group so hospitably at the Santa Rosa Island Research Station. Thanks to Jim Roberts, NPS for his generous GPS support. Thanks to Sarah Chaney for inspiring this project with her ingenuity.