Desert Habitats Climate Change Vulnerability, Adaptaon Strategies, and Management Implicaons in Southern California Naonal Forests Habitat Descripon

There are three deserts in southern California: the Mojave Desert, the Colorado Desert (a subdivision of the larger Sonoran Desert), and the less well-known San Joaquin Desert, which historically and included much of the San Joaquin Valley, Carrizo Plain, and Cuyama Valley. These desert ecosystems contain the highest temperature extremes in the United States; topographical relief in these desert ecosystems ranges from 86 m below sea level in Death Valley up to 3300 m above sea level in the Panamint Range. BLM/Photo by Bob Wick (CC by 2.0) Habitat Vulnerability Desert habitats are sensive to climate drivers that Moderate exacerbate the already hot and dry condions, enhancing Vulnerability vulnerability for many species that already exist close to Low High their physiological limits. Climate drivers and disturbances (e.g., changes in precipitaon, flooding, Drivers of Desert Habitats wildfire) have the potenal to significantly alter species • Climate sensivies: Precipitaon, soil survival and composion. Slow-growing vegetaon moisture, low stream flows, drought, extreme makes deserts parcularly vulnerable to invasive grasses, heat events which provide fine fuels for wildfire; ulmately, the cycle • Disturbance regimes: Wildfire, flooding of invasive species and wildfire can cause type conversion

Sensivity & Exposure to grasslands . Non-climate stressors have already • Non-climate sensivies: Invasive species disturbed and/or fragmented many desert habitats.

Projected Climate and Climate-Driven Changes Potenal Impacts on Desert Habitats

Changes in precipitaon, decreased soil • Loss of crical water sources and associated microclimate moisture, and increased drought refugia (e.g., palm oases) Changes in ming and amounts of seasonal • Changes in plant phenology (e.g., germinaon, blooming) precipitaon; longer, more severe droughts with • Increase in drought-adapted vegetaon, including succulents droughts years twice as likely to occur • Reduced seedling establishment, leading to older age classes Increasing temperatures & extreme heat events • Increased evapotranspiraon and loss of soil moisture +2.5 to +9°C by 2100; heat waves will occur more • Increased dependence of wildlife on underground thermal frequently, last longer, and feature hoer refugia, reducing opportunies to forage temperatures • Damaged ability of plants to photosynthesize Altered fire regimes • Altered species composion and populaon structure Increased fire size, frequency, and severity • Increased invasive annual grasses and associated increases in availability of fine fuels, leading to more fire • Direct mortality, reduced survival, and reduced reproducve success in wildlife (e.g., desert tortoises, western yellow bats)

Factors that enhance adapve capacity: Factors that undermine adapve capacity: + High levels of biodiversity, including many rare, - Plant species are slow to recover from disturbance endemic, and threatened/endangered species and exist close to physiological limits + Species specifically adapted to drought and heat - Habitat migraon limited by anthropogenic and may be able to expand range geological barriers + Limited habitat fragmentaon compared to other - Habitat may not be valued by the public, except for habitat types recreaon opportunies and land use conversion Adapve Capacity + Valued for research potenal (e.g., to agriculture, energy development). Adaptaon Strategies for What kinds of adaptaon opons are there? Desert Habitats Enhance Resistance è Prevent climate change from affecng a resource Promote Resilience è Help resources weather climate change impacts by avoiding the effects of or recovering from changes Facilitate Transion è Accommodate change and/or enable resources to adapvely respond to variable condions Increase Knowledge è Gather informaon about climate impacts and/or management effecveness in addressing climate change challenges Engage Collaboraon è Coordinate efforts and capacity across landscapes

BLM/Photo by Bob Wick (CC by 2.0) and agencies

Adaptaon Adaptaon Strategy Specific Management Acons Category Enhance Design educaonal programs to • Communicate with the public about access to roads and Resistance address potenal safety issues recreaon areas through signage, visitor centers, and and limit non-climate stressors brochures Manage invasive species, • Remove non-nave grasses around possible ignion sites including non-nave grasses • Idenfy the species that may colonize sprayed areas and develop a plan Reduce possibility of severe • Close access to roads and campgrounds during high fire hazard wildfire years or when site needs to recover; direct visitors to more resilient sites Promote Protect and enhance seeps and • Discourage visitor use of springs in sensive spring areas1 Resilience springs, as well as the source • Protect a buffer zone for natural vegetaon around spring sites aquifer(s) that supply them1 to minimize effects of storm runoff1 Facilitate Idenfy and protect desert • Priorize land acquision to target areas with potenal refugia, Transion refugia such as seeps and springs, foothills, and dunes • Protect desert refugia through varied strategies such as land acquision, land use planning, and land transfers Increase Establish monitoring programs • Monitor desert biodiversity, including invertebrates and soil Knowledge to detect changes over me microbial communies Engage Collaborate with decision- • Idenfy current policies that could offer funding or logiscal Collaboraon makers to create policies that support for desert research and restoraon projects support healthy ecosystems

*Acons presented are those evaluated as having higher effecveness and/or feasibility. Management Implicaons This informaon can be used in a variety of ways: Resilient management requires implemenng ✔ Forest Plan Revisions a variety of adaptaon opons ✔ U.S. Forest Service Climate Change Performance Scorecard: Element 6 - “Assessing Vulnerability” and Element 7 - “Adaptaon Acons” ✔ Bureau of Land Management Resource Management Plan Revisions

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

1 Comer, P. J., Young, B., Schulz, K., Kiel, G., Unnasch, B., Braun, D., … Hak, J. (2012). Climate change vulnerability and adaptaon strategies for natural communies: pilong methods in the Mojave and Sonoran deserts. Arlington, VA: Report to the U.S. Fish and Wildlife Service. NatureServe.