Yellow Pine/Mixed Conifer Ecosystems Climate Change Vulnerability, Adapta5on Strategies, and Management Implica5ons General Informaon: The mixed conifer forest is the most widely distributed forest type, covering an es=mated 10% of vegetated area in the Sierra Nevada. Mixed conifer forests are found between 1219-2438 m (4000-8000 L) elevaon and include tree species such as black oak (Quercus kellogii), ponderosa pine (Pinus ponderosa), incense cedar (Calocedrus decurrens), sugar pine (Pinus lamber5ana), 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 condi=on 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. Mar>n Although plant composi=on has changed, most species are s=ll present. Ecosystem Vulnerability: Moderate Yellow pine/mixed conifer ecosystems are sensi=ve 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 composi=on 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 poten=al 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 composi=on • 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 composi=on 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 poten=al climate impacts will likely be enhanced by their Yellow pine/mixed conifer forests in cool occurrence across a broad geographical and elevaonal distribu=on, canyons, northern aspects, and favorable u=lizaon 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 Adapta>on Strategies for Yellow Pine/Mixed Conifer Ecosystems Adapta>on Strategy Specific Management Ac>ons Restore structure, funcon, and • Assisted translocaon of species to suitable habitat in the future composi5on 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., gene=cally resistant to white pine blister and processes now and in the rust) future • Prac=ce targeted thinning of fire-intolerant species to minimize fuel loading, reduce poten=al fire severity, and reduce risk of insect and disease outbreaks • Use prescribed burning to restore ecosystem func=on, minimize fuel loading, reduce poten=al fire severity, and reduce risk of insect and disease outbreaks • Ac=vely manage natural fires by managing fire path and severity to meet management objec=ves and reduce risk of catastrophic fires Monitor success to evaluate • Iden=fy key metrics (i.e., indicator species, structure aributes, important whether adaptaon ac=ons are func=ons) to evaluate climate and non-climate impacts and management working and/or need to be revised ac=on effec=veness • Establish realis=c, long-term monitoring programs to track above metrics © Gey Images © WERC © W. Siegmund Restoring forest structure, func>on, and species composi>on through a variety of management ac>vies (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 Implica>ons 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 Ac=ons” ✔ 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 Adapta5on Strategies for Focal Resources of the Sierra Nevada, available online at the EcoAdapt Library: hcp://ecoadapt.org/library. .