Analysis of Coast Live Oak (Quercus agrifolia) Survival Following Restoration Planting in the Santa Cruz Mountains of California

Oak woodland habitats have been reduced, degraded, and fragmented due to human development. The successful planting of foundational oak species is a step towards restoring lost habitat and supporting the many species that depend on oak woodlands. Previous studies have found that soil compaction, soil moisture, and a variety of other environmental factors can influence the success of Quercus (oak) seedlings. However, there is a lack of field data on the importance of these factors for the species Quercus agrifolia (coast live oak). To test the relative effect of these factors, a Q. agrifolia acorn planting was conducted in the Santa Cruz Mountains of California. Success of the seedlings, based on height and survival of germinated acorns, was measured for one year and four months following planting. Variables related to these success metrics were examined using Pearson’s correlation, Cox regression, and stepwise regression analyses. Results indicated negative associations between seedling survival and high levels of available nitrogen, soil moisture, soil compaction, and increasing distance from the tree line. Some of these results were unexpected, as a lack of nutrients and soil moisture are often linked to seedling mortality. In this case, however, it appears that waterlogging related to soil compaction, and high excessive levels of nitrogen resulting from applied fertilizers, may have been connected to reduced seedling survival.