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  • Title

    Monitoring and Evaluation of the North Delta Food Subsidies and Colusa Basin Drain Study

    Lead California Department of Water Resource [DWR]
    Description The North Delta Food Subsidies – Colusa Basin Drain Study monitors and evaluates the effects of the North Delta Flow Action on the Delta food web.
    Science topics Delta Smelt, Fish, Flows, Water management
    Updated November 17, 2022
  • Title

    Effects of drought and elevated nutrients on invasion by Lepidium latifolium and implications for carbon storage in tidal wetlands of the San Francisco Bay- Delta

    Lead Delta Stewardship Council - Delta Science Program
    Description The Delta ecosystem is under threat from multiple concurrent stressors, including drought, nutrient pollution, and invasion by non-native species. Lepidium latifolium is an invasive peren- nial plant that displaces native species and may reduce carbon storage in tidal marshes. Preliminary data suggest that drought may be detrimental to L. latifolium invasion, whereas elevated nutrients may promote invasion. Using experimental manipulation of tidal marsh plots, this project will test the impact of drought and elevated nutrients on the invasion of L. latifolium. The results will inform management of L. latifolium in the Bay Delta by identifying its vulnerabilities to climatic and nutrient conditions, and will be shared with management agencies including East Bay Regional Parks, San Pablo Bay National Wildlife Refuge, and Palo Alto Baylands, among others. The results will also be integrated with the PI’s dissertation research on the carbon storage capacity of L. latifolium, in order to inform wetland carbon offset policies.
    Science topics None specified
    Updated December 21, 2023
  • Title

    Carbon Biogeochemical Cycling in Tidal Wetlands: Exploring Lateral Carbon Exchange and Sequestration Potential

    Lead University of California - Berkeley [UC Berkeley]
    Description Tidal wetlands, at the interface of land and ocean, play a critical role in carbon biogeochemical cycling and have the potential to provide major feedback to the Earth system through greenhouse gas exchange and long-term carbon sequestration. However, the efficiency of carbon sequestration in tidal systems relies on both vertical carbon exchange with the atmosphere and lateral tidal exchange with adjacent water bodies. Unfortunately, the importance of hydrologic carbon fluxes has been largely overlooked, leaving a crucial aspect of coastal wetland net carbon balance unaddressed. We employed an integrated approach to quantify vertical and lateral carbon exchange and studied their dynamics, combining eddy covariance flux measurements with on-site water quality and tidal discharge measurements, as well as manual 24h surface water samplings. Our measurements were conducted in a recently restored tidal freshwater marsh in the Sacramento-San Joaquin Delta, CA, that stands out in global networks like FLUXNET and Ameriflux owing to its impressive net ecosystem exchange of -850 g C m-2 yr-1. Using wavelet decomposition, we examined the variability of carbon exchange (CO2 and CH4) across different timescales. Through information theory and mutual information analysis, we assessed the factors influencing both vertical and lateral exchanges. Our preliminary findings suggest that variability in carbon exchange is largest at the diel scale, with plant gross primary productivity and tidal fluctuations in depth having the most significant interactions with CO2 and CH4 fluxes, respectively. Furthermore, our tidal cycle samplings revealed that dissolved inorganic carbon dominates the fraction of lateral carbon loss, accounting for approximately 80% of the export. Remarkably, similarities existed between the values for net lateral carbon export and ecosystem respiration, signifying that the dissolved, terrestrial-to-ocean carbon flux could represent one of the primary fates of the fixed carbon in this tidal ecosystem. These large dissolved inorganic carbon fluxes and their chemical speciation, are important to consider when estimating the climate mitigation potential of restored tidal wetlands.
    Science topics Carbon, Carbon storage, Greenhouse gas GHG
    Updated January 30, 2024
  • Title

    Pixel-Wise Footprint Analysis of GPP Using High-Resolution NDVI/NIRv Data

    Lead University of California - Berkeley [UC Berkeley]
    Description Spectral indices such as NDVI have long been found to be good predictors of plant productivity at many spatial scales from the canopy to the landscape. Spectral indices are an important tool for upscaling GPP fluxes we measure at the ecosystem scale through Eddy Covariance up to larger spatial scales. Other indices, such as NIRv (expressed as NDVI * total NIR) have also been shown to be potentially more accurate predictors of GPP using in-situ spectral measurements than NDVI alone. Additionally, associating spectral signals within modeled flux footprint areas has been shown to improve the predictive capability of spectral indices compared to estimates using remotely sensed data centered directly on top of flux towers. Most if not all of these spatially explicit footprint analyses have been done by aggregating footprints into polygons based on their 50%-90% estimated flux contributions, and then associating those polygons with fluxes and spectral signals within them. This approach has been necessary largely because of the spatial scales involved with satellite remote sensing products, reaching a practical minimum of 3m, downsampled from 4.8m imagery by Planet Labs. By combining pixel-weighted flux footprint contributions with ultra-high resolution (3cm) spectral drone data, we will examine and compare how different spatial scales and indices affect the capability of spectral data to predict fluxes which are not directly measured.
    Science topics None specified
    Updated January 30, 2024