Climate Change, Conservation Science, and Adaptive Management 1

Thursday, October 20 at 1:00-2:40 pm, Pine Room

*note alternate instance of this session – Friday at 1pm

Session Description: Climate change poses novel risks to species, from contributing to changing fire regimes, drought, the spread of invasive species, and influencing shifts in the ranges for native species. This session will focus on climate change through the lens of conservation science, how this impacts management decisions, and how adaptive management is more important now than ever.

Session Chair: Robin Murray (Rincon Consultants, Ventura, CA, USA))

8.1 Change afoot in California’s alpine plant communities

Dena Grossenbacher, Dena Paolilli, and Rachel Friesen (California Polytechnic State University, San Luis Obispo, CA, USA)

In alpine regions, climate warming is predicted to cause plant community shifts towards species from warmer climates. However, slow growth rates coupled with limited dispersal in alpine habitats may lead to considerable lags in community level responses. Here we revisit more than 100 historic alpine plots across Kings Canyon, Sequoia, and Yosemite National Parks in California. We find that over a 30 year period, communities experienced a >25% increase in species richness and mean phylogenetic diversity respectively, and a shift towards warmer affinity species on average. Species’ colonizations and extinctions varied depending on species’ climate affinities consistent with there being winners and losers. Extinctions were greater for species from cooler wetter regions, while colonization were greater for species from drier regions. These results are contrasted to community shifts at lower elevations in California, and we discuss them in light of model projections and management proposals for our alpine flora.

8.2 Influence of seed source on establishment and growth of restored coastal sage scrub under varying rainfall regimes

Julie Coffey (UCI Nature, University of California Irvine, Irvine, CA, USA), Andrew Laleian (MCRS, University of California Irvine, Irvine, CA, USA), Elias Potashov (MCRS, University of California Irvine, Irvine, CA, USA), Hailley Coleman (MCRS, University of California Irvine, Irvine, CA, USA), Megan Lulow (UCI Nature, University of California Irvine, Irvine, CA, USA), Moises Perea-vega (UCI Nature, University of California Irvine, Irvine, CA, USA), Sarah Kimball (Center for Environmental Biology, University of California Irvine, Irvine, CA, USA)

Climate change has led to unpredictable weather patterns in Southern California. Rainfall events are expected to become less frequent and more concentrated, resulting in surges and droughts of available water. Specifically, vulnerable native coastal sage scrub and grassland habitats will be impacted by this variability. Facing these changes, restoration practitioners must decide what types of plants to use in restoration. Locally sourced seeds may not be best suited for future climatic conditions. In Orange County, practitioners generally try to source coastal seed for coastal projects and inland seed for inland projects. Some suggest that the success of plant establishment in restoration in a changing climate may be improved by including seeds or plants sourced from non-local, arid conditions. To address this uncertainty, we answered the following questions:  1. How does seed source influence the success of restoration?  2. Are inland seed sources better able to survive experimentally induced drought than coastal seed sources?  3. What traits, if any, differ significantly between seed sources within a species? Our results show that inland-sourced Deinandra fasciculata and Stipa pulchra had significantly higher abundance in ambient plots ten week after seeding than their coastal-sourced counterparts. We additionally found that seeds from coastal populations of S. pulchra had significantly higher abundance in irrigated plots than inland seeds ten weeks after seeding and that coastal-sourced Artemisia californica had higher abundance relative to inland-sourced seed six weeks after seeding. Coastal-sourced Encelia californica had higher survival relative to inland populations. Overall, our results suggest that the range of acceptable regions to source seeds from for coastal restoration projects can be broadened. Inland seeds may be better able to survive in coastal restoration projects, but results vary by species.

8.3 Drought, physiology, topography, and the future of western redcedar

Matthew Tomaszewski (Washington State University, Cardno now Stantec)

All living organisms have the capacity to maintain fitness in the face of environmental stressors through changes in morphology and physiology. This process, known as acclimation, is a critical component in the distributional formation of land plants across ecotypes and understanding how land plants will acclimate to global climate change is a current research priority. The growing season of 2021 brought historically significant levels of water stress to forests across the region due to an unprecedented heat dome and record meteorological drought. During this period, we measured monthly predawn and midday water potentials, foliar chlorophyll surface density, dark adapted chlorophyll fluorescence and leaf gravimetric water content of mature western redcedar trees from three microsites representing different canopy and topographic positions. In addition, we measured Huber value, leaf mass per unit area, osmotic potential at turgor loss point and foliar δ13C of the same individuals. We found that high topographic position had a significant negative effect on predawn water potentials and open canopy position had a significant negative effect on foliar chlorophyll surface density, but no effect on midday water potential. Individuals with open canopy positions had significantly higher Huber value, leaf mass per unit area and δ13C. Our results demonstrate the ability of western redcedar to adjust morphology and physiology in response to variable environmental conditions and suggest that trees in open canopy positions may have increased water use efficiency compared to closed canopy positions. This acclimation suggests that western redcedar, a late-successional mesic forest species, has some ability to tolerate the hot and dry conditions expected with future climate change, if the change is not more rapid than the trees’ ability to replace their leaf area with better adapted phenotypes.

8.4 Changing Ecological Conditions in a Critical Wetland in Anza-Borrego Desert State Park and Implications for Restoration

Laurel Brigham (University of California, Irvine, Irvine, CA, USA), Julie Coffey (University of California, Irvine, Irvine, CA, USA), Nikki Fiore (University of California, Irvine, Irvine, CA, USA), Hailey Laskey (University of California, Irvine, Irvine, CA, USA), Moises Perea-Vega (University of California, Irvine, Irvine, CA, USA), Priscilla Ta (University of California, Irvine, Irvine, CA, USA; Anza Borrego Desert State Park), Sarah Kimball (University of California, Irvine, Irvine, CA, USA), Megan Lulow (University of California, Irvine, Irvine, CA, USA)

Sentenac Cienega is a vital freshwater wetland in Anza-Borrego Desert State Park (ABDSP). Dead riparian trees, shortened periods of inundation, and a proliferation of non-natives over the past 15 years prompted ABDSP biologists to seek funding for a hydrological and biological assessment to guide restoration planning. The project is a partnership between ABDSP, the Anza Borrego Foundation, University of California, Irvine (UCI) and University of San Diego. The 890 acre project area includes a reach of riparian vegetation leading to the marsh inlet, the groundwater fed marsh basin, and an emergent spring at the outlet. UCI research focused on documenting current and past hydrology and plant communities, which reflect wide variation in surface and ground water availability and soil physical and chemical properties. Hydrologic and soils measurements included assessment of the water table depth and soil moisture, salinity, pH, and carbon analyses across spatial gradients. Observational and experimental studies were conducted to characterize the vegetation. Over time, there has been signicificant drying of the marsh, a proliferation of invasive species, and a shift towards increased abundance of upland species. We also saw differential changes in plant available moisture upstream versus downstream of the inlet over time, and overall low soil moisture levels stymied planting efforts. In order to optimize future ecological conditions with climate change, target restoration communities will need to reflect the changing distribution of water resources, in addition to implementing measures to control invasive species, supplement native plantings with propagules and irrigation, and mediate the impacts of flash floods.