Coast Live Oak, Quercus agrifolia, Planting Success: Lessons from Topanga State Park, Los Angeles County, Santa Monica Mountains

Oak woodlands not only provide critical habitat for hundreds of species, they are an iconic feature of California ecosystems. With extensive oak loss and little natural recruitment, the need for oak tree restoration increases. However, restorations can have varying success and can be a costly endeavor. We analyzed a 3 yr coast live oak restoration project, involving 367 plantings, located at Trippet Ranch within Topanga State Park of the Santa Monica Mountains, in Los Angeles County, to better understand factors that influence oak restoration success and its associated costs. After assessing environmental factors such as planting method, percolation rate, canopy cover, surrounding vegetation, soil type, rainfall, and year planted, we determined that planting sites resulted in significant differences in acorn/seedling survival. Based on a Random Forest analysis we determined that soil percolation, canopy cover, and planting year influenced survival across planting sites. We observed no significant difference in survival rate between acorns and seedlings. We also did not find rainfall to influence survival, potentially suggesting that continued maintenance/waterings contributed to restoration success.