Restoration Management in Redwood Forests Degraded by Sudden Oak Death.

We describe the foundation, objectives, and initial results from a stand-level experiment focused on restoration of redwood (Sequoia sempervirens (D. Don) Endl.) forests impacted by sudden oak death (SOD), caused by Phytophthora ramorum. Our study stands were primed for heavy impacts by SOD. Extensive harvesting which ended circa 1910 on Mt Tamalpais (Marin County, California) resulted in high densities of tanoak trees with interspersed residual redwood. The arrival of P. ramorum and subsequent emergence of SOD transformed these stands into tanoak shrublands with interspersed redwood trees. Pretreatment understory tanoak densities were extremely high relative to redwood forests of the north coast which have not been invaded by P. ramorum but both redwood advanced regeneration and overstory tree densities were low in the same respects. Mastication and hand-crew piling treatments were applied in 2015 on a randomly selected group of plots and each treatment type substantially reduced tanoak densities suggesting redwood establishment may now be possible. Our study is designed to assess tradeoffs of treatment costs with benefits resulting from fuels reduction, redwood regeneration, carbon sequestration, and water provisioning. We cannot yet make strong conclusions about these tradeoffs given the preliminary nature of our datasets. Instead, we describe areas of uncertainty and identify critical questions that must be evaluated to understand the utility and appropriateness of applying these treatments across a broader portion of the redwood forest landscape. [ABSTRACT FROM AUTHOR]