Spatiotemporal Patterns of Mineral and Organic Matter Deposition Across Two San Francisco Bay-Delta Tidal Marshes
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WETLANDS AND CLIMATE CHANGE
Spatiotemporal Patterns of Mineral and Organic Matter Deposition Across Two San Francisco Bay-Delta Tidal Marshes Kevin J. Buffington 1
&
Christopher N. Janousek 2 & Karen M. Thorne 1 & Bruce D. Dugger 2
Received: 16 March 2019 / Accepted: 9 December 2019 # US Government 2019
Abstract Sediment deposition in tidal wetlands is a critical process that determines whether vertical growth will keep pace with sea-level rise. However, more information is needed on how sediment deposition varies spatially and temporally across wetlands, including the effects of elevation, tidal inundation, vegetation, and weather. We investigated variation in sediment deposition due to season, distance from channel, channel size, and vegetation composition at low and high salinity tidal marshes in the San Francisco Bay-Delta Estuary, California using sediment traps deployed monthly between December 2015 and November 2016. Over the course of the year, sediment deposition ranged widely (1.4 – 174.0 kg m−2 yr−1) and averaged 19.5 ± 3.5 kg m−2 yr−1. Deposition increased with flooding duration, decreased with increasing distance from channels, and was highest during the spring and early summer. Higher wind speeds during the spring may have driven re-suspension from mudflats, promoting deposition. Ratios of organic-to-mineral deposition were twice as high at the fresher site and were correlated with differences in vegetation composition between sites. Our results suggest that seasonality, distance from sediment source, salinity regime, and channel size are important sources of spatiotemporal variation in deposition. These results are relevant to accretion sampling and wetland restoration design. Keywords Accretion . San Francisco Bay . Sea-level rise . Sediment deposition . Sediment traps . Tidal wetland
Introduction Tidal marshes are dynamic coastal ecosystems with the ability to gain or lose vertical elevation and spatial extent in response to changes in sea level (Kirwan and Megonigal 2013; Kirwan et al. 2016a; Thorne et al. 2018). Vertical elevation building or accretion processes include the deposition of mineral sediments delivered by the tides and in situ organic matter contributions that include the production of root and rhizome biomass belowground (Morris et al. 2002; Nyman et al. 2006). Lateral changes in marsh extent can include migration into Electronic supplementary material The online version of this article (https://doi.org/10.1007/s13157-019-01259-3) contains supplementary material, which is available to authorized users. * Kevin J. Buffington [email protected]; [email protected] 1
Western Ecology Research Center, U.S. Geological Survey, One Shields Ave, USGS Davis Field Station, Davis, CA 95616, USA
2
Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR, USA
uplands, marsh progradation, or marsh edge erosion (Kirwan et al. 2016b). Along the Pacific coast of the United States, organic matter versus mineral inputs to tidal wetland accretion vary, with allochthonous
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