Skip to main content
eScholarship
Open Access Publications from the University of California

Scholarly Works (10 results)

  • Article
  • Peer Reviewed
UC Davis Previously Published Works (2020)
The 7-million-acre Sacramento River Headwaters Region, and its surrounding 3-million- acre buffer zone, has an extraordinarily important role for biodiversity as well as water supply in California. Delineated by three mountain ranges (the northern Sierra, southern Cascade and Klamath-Trinity) it has a widely varied topography, range of soil types and geology that support an extraordinarily wide variety of plants and habitats. The region contains over 80% of California’s natural habitat types and hosts over 60% of its vertebrate species, 62 of which are imperiled. One of 33 globally recognised biodiversity “hot spots”, it is also the source of the vast majority of California’s utilized water, supplying the largest reservoirs which are the backbone of the state water system. Many species and habitats are already under assault in California due to habitat loss, cover type and land use conversion and habitat degradation. Climate change is clearly exacerbating this trend. This region has more intact habitats than most in California, and presents more opportunity to stem habitat loss and reverse degradation, due to its relatively lower human settlement footprint and population. Meta-analyses show that this region has remained cooler and wetter than the rest of the state over the past 100-125 years, providing a reliable context for consistent habitat function. With such a major role in supporting California’s biodiversity, the focus of this project was to evaluate how persistent this habitat service might be in the future 100 years as climate change intensifies. We utilized the two more plausible Representative Concentration Pathway (RCP) climate change scenarios, the RPC 4.5 and the RPC 8.5, and modelled these under both of the two leading global climate change models: the MIROC—which projects a warmer and drier future-- and the CRNM—which projects a wetter and warmer future—downscaled to California. Our project identified where the models agree that conditions supporting refugia—and connecting corridors/safe passage to them-- will be 2040, 2070 and 2100. Specifically, we identified where there was a consensus outcome of both models identifying where temperature and precipitation regimes would continue to support the natural habitats—and the amazing array of biodiversity they contain-currently existing in the region. These are critical areas for conservation and restoration, as they will likely continue to support current habitats even under climate change. Additionally, we identified where exposure to precipitation and temperature changes was relatively more moderate, and thus these areas have a strong potential for being able to be resilient under climate change, especially if these areas had been managed to have more natural resilience. These also have high value for conservation and restoration, as they may serve as buffers and risk mitigation allowing more opportunity for species to survive. Finally, we identified those areas where the projected changes in precipitation and temperature will cause environmental stress so great as to likely no longer support the existing habitats, and thus the biodiversity they support. These areas may have high value for conservation for a variety of reasons, but the habitats they support currently are not projected to persist.1Pacific Forest Trust, Final Report WC-1835JG
    Cover page: PLANNING FOR SPECIES ADAPTATION AND CLIMATE RESILIENCE IN CALIFORNIA’S PRIMARY SOURCE HEADWATERS
    • Article
    • Peer Reviewed
    UC Davis Previously Published Works (2020)
    Natural resource managers need information about the risks associated with climate change to provide guidance on where to implement various management practices on natural lands. The spatial variation of projected impacts within a vegetation type can be used to target climate-adaptive management actions because different locations will be exposed to different levels of climatic stress. Vegetation refugia are areas that retain non-stressful climate conditions under future climates. Consensus vegetation refugia – areas retaining suitable climates under both wetter and drier future projections – represent only 14.6% of California's natural vegetation. One state and one federal government agency have incorporated vegetation refugia maps into conservation planning for 522 vertebrate species and for post-wildfire reforestation. Monitoring how vegetation responds to management actions at sites within vegetation refugia can improve the conservation of plants subjected to a changing climate.
      Creative Commons 'BY-NC-SA' version 4.0 license
      • Article
      • Peer Reviewed
      Information Center for the Environment Publications (2015)

      This report documents an assessment of the potential environmental impacts of transportation projects under development by Caltrans for a study area. The report is an update of a previous study, overseen by the by the Regional Advance Mitigation Planning (RAMP) working group (Regional Advance Mitigation Planning Work Group, 2011). The RAMP working group previously selected the pilot project area as a useful area in which to provide an application and test of methods to conduct a regional accounting of the expected impacts from multiple projects. This approach to impact assessment is an integral part of developing regional advance mitigation planning methodologies.

       

      This report provides an overview of the legal obligations for Caltrans with regard to compensatory mitigation, with a listing of the federal and state acts that require special consideration, consultation or permits for impacts to species or habitat, and to the waters of the United States and California, including wetlands. Also provided within each regulation is the presiding jurisdiction or agency that issues the consultation and/or permit and a definition of what the law protects.

        Cover page: 2015 Mitigation Needs Assessment for Transportation Projects for the Sacramento Valley Pilot Project for Regional Advance Mitigation PlanningCreative Commons 'BY' version 4.0 license
        • Article
        • Peer Reviewed
        UC Davis Previously Published Works (2021)
        The many Gondwanic vegetation types found across the extensive latitudes and elevation gradients of South America's southern cone contribute to Chile's global biodiversity hotspot ranking. Species loss in global biodiversity hotspots is an ongoing climate change concern and land managers need spatially explicit climate risk maps to adapt conservation strategies to climate change in these areas. We modeled future climate risk for Chile's terrestrial vegetation using a high-resolution vegetation map and tested the relationship to climate risk for each type's latitudinal and elevation range. We found that 43.6% of all vegetation has high climate risk in Global Circulation Models (GCMs) under a high emissions scenario (RCP8.5). All forest types in the country, including Southern Beech (Nothofagus sp.), Alerce (Fitzroya cupressoides), Araucaria (Araucaria araucana), and Sclerophyllous, as well as the Valdivian rainforest, Altiplanic Steppes, and Salares, face high levels of climate risk. Tests for trends in risk across elevation and latitude showed that exposure for all types increased with elevation based on the MIROC5 GCM, and decreased with latitude based on the Had2GEM-ES GCM. Our results suggest that vegetation types with smaller latitudinal ranges typically have higher levels of climate risk, but a type's elevation range is not significantly correlated with risk of exposure. We identified climatically stable areas which could act as vegetation refugia in Patagonia, the central Andes mountains between latitudes 27.5°S and 32.5°S, and some coastal areas. Conservation strategies in Chile should include the protection of climatically stable areas to safeguard current Gondwanic biodiversity and active habitat restoration in climatically exposed areas to facilitate vegetation shifts.
          • Article
          Research Reports (2021)

          Catastrophic wildfires over the past five years (2015-2020) have caused damage to the Caltrans road network in 81 separate wildfire events, leading to expenditures of over $590,000,000 to repair highway assets. To reduce the risk of further wildfire damage and to improve public safety, particularly for disadvantaged communities, Caltrans has engaged in assessing the priority locations for vegetation treatment within the lands it owns called the Right of Way (ROW). A 2019 analysis provided a map showing the top 17% of vulnerabilities in the road network, representing both the risk of wildfire and to disadvantaged communities that might need to use the transportation network as means of evacuation. This UC Davis research project was designed to support efforts within Caltrans in conducting a wildfire vulnerability risk assessment for fuels reduction in the ROW to protect Caltrans’ infrastructure and travelers. The project involved four components: 1) conducting a rigorous peer review of the 2019 GIS-based study commissioned by Caltrans; 2) collecting and assessing the outputs of several climate change, fire, and other models currently developed or under development for California, as well as future climate projections; 3) developing a framework for the use of the prioritized segment model with other data further identify priority areas for fuels and risk reduction; and 4) interviews with Caltrans staff on opportunities and obstacles to increasing the pace and scale of vegetation treatments. The results contribute to infrastructure risk assessments, can be used to prioritize areas for treatment, to create a tracking system of areas treated and risk lowered over multiple years, and to engage local governments and wildfire fighting units to coordinate landscape fire risk reductions.

          View the NCST Project Webpage

            Cover page: 2020 Critical Update to Caltrans Wildfire Vulnerability Analysis
            • Article
            • Peer Reviewed
            UC Davis Previously Published Works (2020)
            As human populations move into cities they are increasingly isolated from the natural world, with associated negative impacts on health and well-being. However, as cities renew themselves through urban redevelopment and climate-adaptation, opportunities arise to improve people's access to urban green areas that can be informed by modeling the network of urban open spaces. Recent research identified the need for multi-criteria indices of access to urban green spaces. Including open spaces such as empty lots, ground- A nd air-spaces surrounding buildings, and spaces associated with roads and other linear features can improve planning for urban greenspaces by identifying areas of opportunity for additional greening. Further, the gradient of interconnections among open spaces can be used to prioritize urban greening locations to build green networks. We modelled all open-space connections across 605 km2 in Seoul, population 10.3 million, using Omniscape, a landscape connectivity model. We combined the resulting open-space connectivity map with distance-based indices for existing urban parks and street trees. Combining these criteria permits rank-prioritization of locations where new green spaces would most improve residents' access. We found 2910 of 3375 (86.2%) locations where urban green spaces already exist within 300 m for city residents. Of the remaining 465 locations, 276 are in areas with the lowest-open space connections. For urban street trees, 44.3% of the 2588 km of the city's major roads are already planted with street trees. Of the remainder, 210 km (8.1%) are located in the areas with the least connections to green spaces. Nine new urban parks would provide relief for the most highly-impacted areas, where the flow of open space is lowest and where no green spaces are available within 300 m. The integration of a spatial model typically used for conservation assessments with city planning provides useful additional context for building urban health.
              Creative Commons 'BY-NC-SA' version 4.0 license
              • Article
              Policy Briefs (2022)

              A key function of a highway network is to maintain access during normal and emergency operations. During wildfire evacuations, first-responders and firefighters depend on highways and local roads for transporting heavy equipment to communities in need. The California Department of Transportation (Caltrans) is expanding vegetation management to begin establishing defensible space zones along California’s nearly 16,000 miles of state highways and in about 230,000 acres of highway right-ofway. However, extended drought, a longer fire season, and higher temperatures brought on by climate change, along with the spread of invasive weeds and dense, dry vegetation, have created new challenges.

              The California Department of Forestry and Fire Protection produced a Community Wildfire Prevention and Mitigation Report in 2019 with a methodology to assess wildfire risk. Caltrans and researchers at the University of California, Davis applied these methods to develop a highway-segment-specific prioritization model for vegetation management within highway rights-of-way. The researchers also interviewed Caltrans staff about opportunities for and obstacles to increasing the pace and scale of vegetation treatments. This policy brief summarizes the findings from that research and provides policy implications.

              View the NCST Project Webpage

                Cover page: A Model for Efficiently Allocating Resources to Mitigate Wildfire Risk along California Roadways
                • Article
                • Peer Reviewed
                UC Davis Previously Published Works (2017)
                This study used tree data from field plots in urban areas to describe forest structure in urban areas throughout California. The plot data were used with numerical models to calculate several ecosystem services produced by trees. A series of transfer functions were calculated to scale-up results from the plots to the landscape using urban tree canopy (UTC) mapped at 1-m resolution for each combination of 6 land use classes and climate zones. California's UTC covered 15% of the urban area and contained 173.2 million trees, five per city resident. UTC per capita was lowest among U.S. states (90.8 m2), indicating ample opportunity for tree planting. Oaks were the most abundant taxon (22%) and overall plantings were youthful. The annual value of ecosystem services was estimated at $8.3 billion and the urban forests asset value was $181 billion. Assuming an average annual per tree management cost of $19 and benefit of $47.83, $2.52 in benefit was returned for every dollar spent. The threat posed by Invasive Shot Hole Borer (Euwallacea sp.) illustrates that urban forests are a relatively fragile resource whose contributions to human health and well-being can be suddenly jeopardized. One scenario projected that should Southern California cities lose 50% (11.6 million) of all susceptible trees, the value of ecoservices foregone over 10 years was $616.6 million. The approximate cost of removing and replacing the trees was $15.9 billion. Strategies to reduce the risk of catastrophic loss by increasing the resilience of California's urban forests are discussed.
                  Creative Commons 'BY-NC-SA' version 4.0 license
                  • Article
                  • Peer Reviewed
                  UC Davis Previously Published Works (2017)
                  The impacts of different emission levels and climate change conditions to landscape-scale natural vegetation could have large repercussions for ecosystem services and environmental health. We forecast the risk-reduction benefits to natural landscapes of lowering business-as-usual greenhouse gas emissions by comparing the extent and spatial patterns of climate exposure to dominant vegetation under current emissions trajectories (Representative Concentration Pathway, RCP8.5) and envisioned Paris Accord target emissions (RCP4.5). This comparison allows us to assess the ecosystem value of reaching targets to keep global temperature warming under 2°C. Using 350,719 km2 of natural lands in California, USA, and the mapped extents of 30 vegetation types, we identify each type's current bioclimatic envelope by the frequency with which it occupies current climate conditions. We then map the trajectory of each pixel's climate under the four climate futures to quantify areas expected to fall within, become marginal to (outside a 95% probability contour), or move beyond their current climate conditions by the end of the 21st century. In California, these four future climates represent temperature increases of 1.9-4.5°C and a 24.8 to +22.9% change in annual precipitation by 2100. From 158,481 to 196,493 km2 (45-56%) of California's natural vegetation is predicted to become highly climatically stressed under current emission levels (RCP8.5) under the drier and wetter global climate models, respectively. Vegetation in three California ecoregions critical to human welfare, southwestern CA, the Great Valley, and the Sierra Nevada Mountains, becomes >50% impacted, including 68% of the lands around Los Angeles and San Diego. However, reducing emissions to RCP4.5 levels reduces statewide climate exposure risk by 86,382-99,726 km2. These projections are conservative baseline estimates because they do not account for amplified drought-related mortality, fires, and beetle outbreaks that have been observed during the current five-year drought. However, these results point to the landscape benefits of emission reductions.
                    Creative Commons 'BY-NC-SA' version 4.0 license
                    • Article
                    • Peer Reviewed
                    Information Center for the Environment Publications (2015)
                    This report represents a collaborative effort between the Information Center for the Environment, Department of Environmental Science and Policy, University of California, Davis (UCD-ICE); the Urban Ecosystems and Social Dynamics Program, Pacific Southwest Research Station, USDA Forest Service (USFS-PSWRS); and the California Department of Forestry and Fire Protection, Fire and Resource Assessment Program (CAL FIRE-FRAP), to assess the current status of the tree canopy and associated benefits within the urban areas of California. In addition, the current status of environmental threats to the urban area population were also examined, in order to highlight the communities most vulnerable and potentially the most likely to benefit from tree plantings and maintenance.
                      Cover page: Biomass, Carbon Sequestration, and Avoided Emissions:  Assessing the Role of Urban Trees in CaliforniaCreative Commons 'BY' version 4.0 license
                      Top