Oak Woodland Ecosystems Climate Change Vulnerability, Adaptaon Strategies, and Management Implicaons

© Yath General Informaon: Oak woodlands exist largely (>80%) on private lands of the Sierra Nevada foothills. Distribuon of remaining oak woodlands occurs on public lands at higher elevaons (1219-1828 m; 4000-6000 ) with low fragmentaon. Canopy species in oak woodlands include blue oak (Quercus douglasii), valley oak (Quercus lobata), canyon live oak (Quercus chrysolepis), and California black oak (Quercus kelloggii), as well as other species present in smaller amounts, such as Oregon white oak (Quercus garryana), incense cedar (Calocedrus decurrens), ponderosa pine (Pinus ponderosa), aspen (Populus tremuloides), willow (Salix spp.), and alder (Alnus spp.). Oak woodlands support over 330 species of birds, mammals, reples, and amphibians – the highest animal biodiversity of all habitats in California.

Ecosystem Vulnerability: Low-Moderate Although oak woodlands are sensive to climate and climate-driven Very Low Very High changes that can alter species composion or recruitment success - including reduced precipitaon and soil moisture, and increased fire frequency and severity - oak woodlands are generally expected to expand in the future, as component species can tolerate warm condions, drought, and moderate fire condions. Oak woodlands are more sensive to non-climate stressors, including herbivory, pathogens, insects, and habitat conversion for agriculture and urban/suburban development. For example, herbivory by cale and wild animals in spring and summer can limit oak recruitment and seedling or sapling establishment, which may be naturally reduced by climac water deficits. Land use conversion has already significantly reduced oak woodland extent in California, and is likely to be a connued problem.

Projected Climate and Climate-Driven Changes Impacts on Oak Woodland Ecosystems Changes in precipitaon and snowpack: • Changes in species composion - Decreased summer and fall precipitaon • Reduced soil moisture, which can affect recruitment and - Decreased snowpack (-64% to -87%), establishment especially in northern range • Altered pathogen exposure - Earlier snowmelt Increased climac water deficit by up to 44%, • Reduced soil moisture, which can affect recruitment and especially in the northern range establishment Increased fire frequency and intensity, with a • Long term effects are unknown: 65% increase in area of oak woodlands burned - Low intensity fire may prevent conifer encroachment and prepare adequate seedbed condions - Moderate intensity fire resulng in oak topkill may impair and/or prolong regeneraon me Oak woodland resilience is generally enhanced by broad ecosystem distribuon, high diversity, and drought- and Oak species that can tolerate warm and dry wildfire-tolerant adult trees. Once disturbed, however, this condions (e.g., valley oak) may be more system has slow regrowth and regeneraon rates, as resilient to climate and climate-driven seedlings are sensive to soil moisture deficits and wildfire. changes than species that require cool, mesic Low elevaon oak woodlands occurring on private lands may condions (e.g., canyon live oak) be more vulnerable due to reduced management potenal. Adaptaon Strategies for Oak Woodland Ecosystems

Adaptaon Strategy Specific Management Acons Restore structure, funcon, and • Plant nave bunch grasses within oak woodlands to reduce spread of invasive composion of oak woodlands to species limit high severity fires and • Use prescribed burning at small-scales to remove non-nave grasses moisture stress • Plant and protect acorns and seedlings from browsing • Fence priority oak areas or individual plants to exclude browsers Idenfy and protect oak climate • Idenfy and priorize areas where water deficit is expected to be minimal refugia to use as priority areas for • Establish extra protecon for priority refugia areas using management conservaon and restoraon designaons, management acon plans, and by excluding humans and browsers Facilitate oak translocaon by • Plant exisng genotypes that are beer adapted to future condions (dry and planng “climate-smart” warm) seedlings in areas that will be • Plant seeds from a greater geographic range or from drier, warmer climates climacally suitable in the future • Maintain genec diversity Engage the public in oak • Increase educaon on intrinsic value and ecosystem services of oaks woodland stewardship • Encourage climate-smart restoraon acvies and volunteer work days • Engage community service organizaons • Enhance stewardship on private lands Maintain and enhance landscape • Idenfy and priorize top predators for re-introducon/re-establishment habitat connecvity and funcon and evaluate habitat needs to support top predators, which • Implement habitat mapping to locate priority areas now and in the future will reduce herbivory thus liming • Use connecvity modeling (e.g., Circuitscape, www.circuitscape.org/) to synergisc impacts on oak idenfy important pinch points for protecon, and priorize climate- woodlands informed protecon or restoraon of these important areas

Minimizing non-climate stressors that compound climate- driven impacts on oak recruitment and fitness can help make this system more resilient to climate change

Management Implicaons This informaon can be used in a variety of ways: ✔ Forest Plan Revisions ✔ U.S. Forest Service Climate Change Performance Scorecard: Element © EPA 6 - “Assessing Vulnerability” and Element 7 - “Adaptaon Acons” ✔ Naonal Park Service Resource Stewardship Strategies, Fire and Fuel Management Plans, General Management Plans, Strategic Plans, and Wilderness Stewardship Plans ✔ May help facilitate public and private partnerships

Further informaon and citaons can be found in source reports, A Climate Change Vulnerability Assessment for Focal Resources of the Sierra Nevada and Climate Change Adaptaon Strategies for Focal Resources of the Sierra Nevada, available online at the EcoAdapt Library: hp://ecoadapt.org/library.