Book
Environmental change in San Francisco Estuary tidal marshes (California)
01 Jan 2006
Abstract
Analysis of historic aerial imagery, monitoring of sediment accumulation and geochemical analysis of sediments, re-survey of vegetation transects established in the 1970s, and description of the stratigraphy and chronology of twenty-four South San Francisco Bay marshland sediment cores provide a record of how vegetation and sediment accumulation in San Francisco Estuary marshlands have responded to environmental change throughout the late Holocene and early Anthropocene. Overall, these analysis show that San Francisco Estuary tidal marshes are dynamic on every time scale studied. Summary of findings: (1) Temperature appears to play a role in marsh establishment, as the main colonizing plant in Central Californian tidal wetlands, Spartina foliosa, is a C sub(4) grass, heavily responsive to small increases in temperature. (2) Sediment deposition is focused at locations low in the tidal frame, close to channels and the shoreline, and locations where vegetation has established relatively recently. (3) San Francisco Estuary plant distributions appear to be responding to increases in tidal flushing and salinity. (4) Freshwater marshes appear to have been more heavily impacted by invasive species establishment over the past 30 years. (5) Subsidence due to groundwater pumping did not cause marsh loss in South San Francisco Bay, as the area of tidal marsh was reduced by an order of magnitude prior to the onset of subsidence. (6) Marsh establishment in San Francisco Bay appears to track freshwater flow (and mineral sediment supply), and therefore may be treated as a paleoclimate proxy. (7) Much of the marsh in South San Francisco Bay formed only recently. (8) The consideration of South San Francisco Bay sediment deposition as a bulk flux, rather than considering accretion rates for individual marshes, indicates that bulk deposition has been relatively constant throughout pre and post-1850 timescales. This dissertation research project has demonstrated the utility in looking to multiple spatial and temporal scales, and using a number of complementary methodologies, in order to better unravel the effect of changing environmental conditions on sediment accretion and vegetation change in San Francisco Estuary tidal marshes.
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Details
- Title
- Environmental change in San Francisco Estuary tidal marshes (California)
- Creators
- Elizabeth Watson
- Resource Type
- Book
- Language
- English
- Academic Unit
- Biodiversity, Earth, and Environmental Science (BEES)
- Identifiers
- 991019299105304721