Yellow Pine/Mixed Conifer Ecosystems Climate Change Vulnerability, Adaptaon Strategies, and Management Implicaons General Informaon: The mixed conifer forest is the most widely distributed forest type, covering an esmated 10% of vegetated area in the Sierra Nevada. Mixed conifer forests are found between 1219-2438 m (4000-8000 ) elevaon and include tree species such as black oak (Quercus kellogii), ponderosa pine (Pinus ponderosa), incense cedar (Calocedrus decurrens), sugar pine (Pinus lamberana), giant sequoia (Sequoiadendron giganteum), white fir (Abies concolor), Jeffrey pine (Pinus jeffreyi), and red fir (Abies magnifica). Species abundances vary across the Sierra Nevada. The condion of eastside yellow pine and mixed conifer forests is comparable to westside montane pine and mixed conifer forests including denser trees, more uniform forests, fire regimes outside the natural range of variaon, and larger, higher intensity fires. © F. A. Marn Although plant composion has changed, most species are sll present.

Ecosystem Vulnerability: Moderate

Yellow pine/mixed conifer ecosystems are sensive to climate and climate- Very Low Very High driven changes that affect seedling establishment, tree growth, and survival, including increasing temperatures, reduced snowpack, reduced soil moisture, and altered fire regimes. Non-climate stressors such as mber harvest, fire suppression, and pathogens and insects can further increase yellow pine/mixed conifer forest vulnerability to moisture deficits and wildfire by altering species composion and forest structure and/or by reducing tree vigor. By 2070, the Sierra mixed conifer/white fir/Jeffrey pine vegetaon type is projected to decline by 12-32%, while the blue oak/ foothill pine and ponderosa pine/Klamath mixed conifer types are projected to increase. Projected Climate and Climate-Driven Impacts on Yellow Pine/Mixed Conifer Ecosystems Changes Increased temperatures (+2.4 to +3.4˚C), • Increased potenal evaporaon with largest increases during summer • In combinaon with moisture decreases, decreased species fitness Snowpack changes: • Earlier and prolonged dry season • Decreased snowpack (-64% to -87%), • Reduced soil moisture, which can reduce germinaon, increase seed especially in northern range mortality, negavely affect tree growth, or lead to species composion • Earlier snowmelt shis Increased climac water deficit by up to • Reduced soil moisture, which can reduce germinaon, increase seed 44%, especially in the northern range mortality, negavely affect tree growth, or lead to species composion shis Increased fire frequency and intensity • More frequent or intense fires: habitat conversion to shrub or chaparral, changes in forest structure and landscape paerns • Low severity fires: mixed conifer/yellow pine tree regeneraon The ability of yellow pine/mixed conifer ecosystems to cope with or respond to potenal climate impacts will likely be enhanced by their Yellow pine/mixed conifer forests in cool occurrence across a broad geographical and elevaonal distribuon, canyons, northern aspects, and favorable ulizaon of diverse microsites, a heterogeneous response to fire, and microclimates nestled within other high topographical and structural diversity. However, altered forest habitats may be more resilient to structure (e.g., fewer late seral stands) reduces this system’s resilience. projected climac changes Adaptaon Strategies for Yellow Pine/Mixed Conifer Ecosystems Adaptaon Strategy Specific Management Acons Restore structure, funcon, and • Assisted translocaon of species to suitable habitat in the future composion of yellow pine/mixed • Plant and promote climate-appropriate genotypes and species (e.g., drought conifer ecosystems to enhance tolerant species) and preserve ecosystem integrity • Plant disease-resistant species (e.g., genecally resistant to white pine blister and processes now and in the rust) future • Pracce targeted thinning of fire-intolerant species to minimize fuel loading, reduce potenal fire severity, and reduce risk of insect and disease outbreaks • Use prescribed burning to restore ecosystem funcon, minimize fuel loading, reduce potenal fire severity, and reduce risk of insect and disease outbreaks • Acvely manage natural fires by managing fire path and severity to meet management objecves and reduce risk of catastrophic fires Monitor success to evaluate • Idenfy key metrics (i.e., indicator species, structure aributes, important whether adaptaon acons are funcons) to evaluate climate and non-climate impacts and management working and/or need to be revised acon effecveness • Establish realisc, long-term monitoring programs to track above metrics

© Gey Images © WERC © W. Siegmund

Restoring forest structure, funcon, and species composion through a variety of management acvies (e.g., prescribed burns, targeted thinning, assisted translocaon) can increase the resilience of yellow pine/mixed conifer ecosystems to climate and climate-driven changes

Management Implicaons This informaon can be used in a variety of ways: ✔ Forest Plan Revisions ✔ U.S. Forest Service Climate Change Performance Scorecard: Element 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

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.