Potential Impacts of Climate Change on Bay-Delta Tidal Marsh Vegetation V.T. Parker 1, J.C. Callaway 2, E.R. Herbert 1, M.C. Vasey 1, L.M. Schile 3 1 San Francisco State University, 2 University of San Francisco, 3 University of California, Berkeley Climate change is likely to cause substantial shifts in estuarine salinity and water levels over the next century, with higher summer salinities due to reduced snowmelt and higher water levels due to increased global sea-level rise. Field sites: 1. China Camp SP salt marsh 2. Petaluma salt marsh 3. Coon Island 4. Rush Ranch 5. Browns Island 6. Sand Mound Slough Brackish Marshes Salt Marshes Freshwater Marshes Brackish Marshes Salt Marshes Current areas of saltwater-freshwater mixing are indicated by yellow and light blue Future areas of saltwater-freshwater mixing will shift inland, impacting the high diversity, high productivity systems in the Suisun and western Delta regions. Ppt Shifts from Snow to rain Smaller Snowpack Earlier melt Spring floods Increased inundation CO 2 increases Increasing Temperatures Lower Summer flows Reduced Peat formation Increased Estuarine salinity Sea level Rise Our research is focused on evaluating effects of climate change on vegetation dynamics across the estuary, including potential impacts on plant community composition and diversity, primary productivity, and decomposition rates. We are evaluating these dynamics at six marshes along a salinity gradient within the Bay-Delta, from China Camp to Sand Mound Slough. Research support: CalFed Grant 1037 Biodiversity: changes along estuarine salinity gradient. Carbon cycling: productivity and decomposition. Currently processing 2008 season productivity measurements Previous data indicated variable rates ranging from: Salt Marshes: gm m-2 Brackish tidal marshes: gm m-2 Freshwater tidal marshes: gm m-2 High Marsh China Camp Low Marsh Coon Typha domingensis Bolboschoenus maritimus Sarcocornia pacifica Pilot study focuses on 3 species at 2 sites in high and low marsh plots Not a full year cycle yet Early data indicate great variability based on species characteristics Early trends suggest decomposition slows in Low marsh compared to high marsh More saline sites compared to less saline sites Decomposition studies: Productivity studies: Wetland productivity & decomposition link to multiple food-webs Decomposition a major source of DOM and POM Acknowledgements: Eyvan Borgnis, Jessica, Tara Earlier results indicate strong negative relationship between salinity and plant diversity 20 randomly placed 0.1 ha plots used this past season consistent with methods used in other types of vegetation worldwide Early analyses parallel previous results Salt marshes: China Camp has lowest diversity at 12 species Petaluma Marsh has far higher diversity with 23 plant species found in plots Brackish Marshes: Coon Island, similar in salinity to PM has 25 species in plots Rush Ranch contained 53 species Freshwater Tidal Marshes: Browns Island (with an oligohaline interior) is similar in diversity to RR with half the plots analyzed Sand Mound Slough, with only 7/20 plots analyzed possess 75 species Sand Mound Slough Browns Island Rush Ranch Coon Island Petaluma Marsh China Camp Previous results demonstrate a strong negative relationship between salinity and species diversity or productivity

Research support: CalFed Grant 1037 Biodiversity: changes along estuarine salinity gradient. Carbon cycling: productivity and decomposition. Currently processing 2008 season productivity measurements Previous data indicated variable rates ranging from: Salt Marshes: gm m-2 Brackish tidal marshes: gm m-2 Freshwater tidal marshes: gm m-2 High Marsh China Camp Low Marsh Coon Typha domingensis Bolboschoenus maritimus Sarcocornia pacifica Pilot study focuses on 3 species at 2 sites in high and low marsh plots Not a full year cycle yet Early data indicate great variability based on species characteristics Early trends suggest decomposition slows in Low marsh compared to high marsh More saline sites compared to less saline sites Decomposition studies: Productivity studies: Wetland productivity & decomposition link to multiple food-webs Decomposition a major source of DOM and POM Acknowledgements: Eyvan Borgnis, Jessica, Tara Earlier results indicate strong negative relationship between salinity and plant diversity 20 randomly placed 0.1 ha plots used this past season consistent with methods used in other types of vegetation worldwide Early analyses parallel previous results Salt marshes: China Camp has lowest diversity at 12 species Petaluma Marsh has far higher diversity with 23 plant species found in plots Brackish Marshes: Coon Island, similar in salinity to PM has 25 species in plots Rush Ranch contained 53 species Freshwater Tidal Marshes: Browns Island (with an oligohaline interior) is similar in diversity to RR with half the plots analyzed Sand Mound Slough, with only 7/20 plots analyzed possess 75 species Sand Mound Slough Browns Island Rush Ranch Coon Island Petaluma Marsh China Camp Previous results demonstrate a strong negative relationship between salinity and species diversity or productivity Brackish Marshes Salt Marshes Freshwater Marshes Brackish Marshes Salt Marshes Current areas of saltwater-freshwater mixing are indicated by yellow and light blue Future areas of saltwater-freshwater mixing will shift inland, impacting the high diversity, high productivity systems in the Suisun and western Delta regions.