Ecosystem services
Assessing benefits of restoring overstocked forests in a multi-benefit framework, including interaction effects. That is, when a management action is taken to benefit one ecosystem service, there are co-benefits to other ecosystem services. Lead: Max Eriksson. Research done under the Center for Ecosystem Climate Solutions.
Using stakeholder-based fuzzy cognitive mapping to assess benefits of restoration in wildfire-vulnerable forests (Restor Ecol). Based on interviews with resource professionals, we found fire protection perceived as the central benefit of forest restoration, and also providing secondary effects on other ecosystem services, notably air-quality protection, provision of habitat, and carbon storage. Multiple fuels-reduction actions, which were perceived as benefiting fire protection, with subsets also offering strong benefits to other ecosystem services
Sierra Nevada carbon balance
Assessing response of linked water and carbon balances plus ecosystem vegetation to a warming climate. Lead: Weichao Guo. Research done under the Center for Ecosystem Climate Solutions.
Mechanisms Controlling Carbon Sinks in Semi‐Arid Mountain Ecosystems (Glob Biogeochem Cycles). Using a dynamic vegetation-ecosystem model we found that with warming, water limitations on growth and enhanced soil respiration reduce carbon storage; however, CO2 fertilization and associated enhanced water-use efficiency offset this loss. With warming accompanied by CO2 fertilization the Sierra Nevada sequesters at least 200 Tg (2 kg m−2) carbon, versus carbon loss with warming alone. The increase reflects coniferous forests growing at high elevations, and some increase in broadleaved forests at low-to-intermediate elevations. Importantly, uncertainty in fire disturbance could shift our finding from carbon sink to source.
Sierra Nevada water balance
Evaluation of spatial evapotranspiration (ET) product that we are using to assess effects of forest restoration and wildfire on water balance, drought vulnerability, and water benefits of forest restoration. Lead: Jim Roche. Collaboration with Nature Conservancy and Center for Ecosystem Climate Solutions.
Water balance for gaged watersheds in the Central Sierra Nevada, California and Nevada, United States (Front For Glob Change). Evaluation using our previously developed ET product together with gridded precipitation and reported streamflow measurements shows excellent water balance on well-constrained basins, supporting further use of our ET product.
American/Feather River Hydrologic Observatory.
Bringing better information to support water-resources decision making in source-water mountain basins. Lead: Guotao Cui. Collaboration with California Department of Water Resources.
1. Mapping of snow water equivalent by a deep-learning model assimilating snow observations (J Hydrol). Daily prediction of snowpack attributes in complex terrain with deep-learning model, assimilation and bias correction.
2. Precipitation estimates and orographic gradients using snow, temperature, and humidity measurements from a wireless‐sensor network (Wat Resour Res). Blending approach using snowpack measurements from a wireless-sensor network, gauge precipitation, and atmospheric-moisture data to estimate mountain precipitation amount and phase.
3. Assessing multi-year-drought vulnerability in dense Mediterranean-climate forests using water-balance-based indicators (J Hydrol). Application of a deep-learning model to predict drought stress in Giant Sequoia Groves across the southern Sierra Nevada using cumulative, multi-year precipitation minus evapotranspiration (actual water deficit) as a metric.
Critical zone science
Continued focus on synthesis of multi-year investigations at the Southern Sierra Critical Zone Observatory. Two papers focused on nutrient fluxes along broad elevation gradients. Lead: Yang Yang. Collaboration with Pacific Southwest Research Station, USDA Forest Service.
1. Impacts of climate and disturbance on nutrient fluxes and stoichiometry in mixed-conifer forests (Biogeochem). We found the rain-snow transition elevation to provide much more stream export of carbon, nitrogen and phosphorous despite having similar soil concentrations.
2. Climate warming alters nutrient storage in seasonally dry forests: Insights from a 2300 m elevation gradient (Glob Biogeochem Cycles). Pine‐oak and mixed‐conifer forest sites (1160-2015 m elevation (not too dry or hot) had more ecosystem productivity, soil weathering, and cycling of essential elements than the oak savannah (405 m) and subalpine forest (2700 m) sites.
Drought mechanisms
We examine mechanisms driving differences in the observed relationship between precipitation and runoff between drought and non-drought periods, given that less runoff usually observed during droughts than would be expected based solely on precipitation deficit. Lead: Tessa Maurer.
Drivers of drought-induced shifts in the water balance through a Budyko approach (Hydrol Earth Syst Sci). The Budyko framework can be leveraged to decompose shifts in precipitation versus runoff during droughts into “regime” shifts, which result from changes in the aridity index along the same Budyko curve, and “partitioning shifts”, which imply a change in the relationship among water balance components and partitioning of available water.