Submitted to: San Francisco Estuary and Watershed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/18/2011
Publication Date: 12/22/2011
Citation: Grewell, B.J., Whitcraft, C., Baye, P. 2011. Estuarine Vegetation at Rush Ranch Open Space Preserve, San Francisco Bay National Estuarine Research Reserve, California. San Francisco Estuary and Watershed Science. 9(3):1-29 and Appendix, 21pp. Interpretive Summary: This research provides analysis of estuarine vegetation at a National Estuarine Research Reserve (NERR) site (Rush Ranch) in the San Francisco Bay Estuary. The NERR reserve system is a federal and state partnership between NOAA, State Parks, State Bay Conservation Commission, San Francisco State University and a local land trust. The data analyses presented quantify vegetation by hydrogeomorphic setting, and provide a historic perspective of vegetation change. The results indicate 27% of the current estuarine plant species at the reserve are of exotic origin, and several are highly invasive. This contribution also includes a detailed flora compiled from more than twenty years of field surveys. The manuscript and flora (appendix) provide an ecological framework for future monitoring, research and adaptive conservation management at Rush Ranch and in the greater San Francisco Estuary.
Technical Abstract: The Rush Ranch Open Space Preserve (Rush Ranch) includes the largest remaining undiked tidal wetland within the Suisun Marsh region of the San Francisco Estuary. The brackish tidal wetlands grade into transitional vegetation and undeveloped grasslands of the Potrero Hills. We present analysis of diverse vegetation that reflects the estuarine position, land use history, and hydrogeomorphic complexity of the site. These data provide a useful framework for future study of vegetation at this San Francisco Bay National Estuarine Research Reserve site. Rush Ranch includes 4 major estuarine geomorphic units that are widely distributed in the region and support vegetation: subtidal channel beds, fringing tidal marsh, tidal marsh plain and tidal marsh-terrestrial ecotone. These are distinguished by small variations in hydrology and elevation, as noted and described through field research, observations, and historic vegetation mapping data. We evaluate vegetation within each of these landforms, considering each vegetation community as a function of changing physical environment and biological iterations. Past land-use and exotic plant species invasions have substantially altered Rush Ranch tidal marsh vegetation patterns. Our results indicate 27% of the current estuarine-associated flora at Rush Ranch are exotic species, and several are highly invasive. Despite these influences, the reserve’s position in the landscape provides important and increasingly rare habitat linkages between the tidal marsh and upland grasslands, providing great potential for restoration and enhancement. We present a detailed flora and vegetation analysis by hydrogeomorphic setting to provide an ecological framework for future monitoring, research and adaptive conservation management.