Location: Exotic and Invasive Weeds ResearchTitle: Shifting mosaics: vegetation of Suisun Marsh Author
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 11/25/2012
Publication Date: 3/21/2014
Citation: Grewell, B.J., Baye, P.R., Fiedler, P.L. 2014. Shifting mosaics: vegetation of Suisun Marsh. In: Moyle, P.B., Manfree, A., Fiedler, P.L, editors. Suisun Marsh: Ecological history and possible futures. Berkeley, California:University of California Press. p.65-101. Interpretive Summary: Suisun Marsh is one of the most remarkable natural areas in California that is being impacted by climate change and urbanization. A major problem for future management scenarios is that most people view Suisun Marsh as a fairly static entity. They envision its long history of being as it is today, and with the expectation it will continue to be about the same for the indefinite future. The perception that large-scale change to Suisun Marsh is inevitable was the stimulus for a symposium on May 23, 2011: Suisun Marsh in the 21st Century: a landscape of change and opportunity. The symposium in turn was a catalyst for this book, which focuses on the history and future of the Marsh over a 100-year time horizon. The authors provide scientific evidence that shows Suisun Marsh has been a place of constant change. Global warming, rapid sea level rise and urbanization are contributing to accelerate changes in the marsh ecosystem. This means that land and resource management decisions made (or not made) today will have profound effects in the future functioning of the Marsh. This chapter on the vegetation of Suisun Marsh demonstrates why this is so. This chapter draws from paleobotanical and modern evidence to summarize what is known about the vegetation of Suisun Marsh, describes challenges in the management of that vegetation due to aggressive invasion of alien plant species, and projects what is likely to happen to this flora in the future under the effects of sea level rise and different management philosophies. The overall goal of the chapter and the book is to stimulate thinking about the future of Suisun Marsh, to improve marsh management practices and aid in restoration planning.
Technical Abstract: Wetland vegetation varies considerably along the estuarine continuum from San Francisco Bay to the Delta. The estuarine flora of Suisun Marsh is distinctive and supports a number of rare and endangered plant species, that are threatened by alien plant invasions. Conservation and management of Suisun Marsh flora has never been as challenging as in today’s highly modified environment, with looming large-scale changes in physical processes due to climate change adding to that challenge. Plans for ecological restoration and conservation of estuarine flora in Suisun Marsh will be most successful if they encompass projections of future sea level rise and changes to other predicted drivers of vegetation pattern and persistence. Long-term planning with emphasis on providing buffers for the future movement of plants inland may overall reduce the loss of estuarine vegetation. As marshlands migrate upslope with rising tides and colonization of conservation buffer corridors proceeds, a “first come, first served” approach must be avoided, because rapidly assembled plant communities will favor aggressive colonizers (invasive weeds) that will establish on marsh edges. Integrated weed management strategies should minimize non-target effects and simultaneously address multiple, potential invasive species to avoid inadvertent secondary invasions inherent in current single weed species management efforts in the Suisun Marsh. The evidence for a strong causal relationship between artificially reduced salinity and beneficial vegetation change, we argue, is lacking, and impacts on the greater Suisun Marsh ecosystem are poorly known. Success of long-term plans for preservation of Suisun Marsh under climate change scenarios will potentially be enhanced by a move to an integrated management approach that simultaneously considers estuarine vegetation in tidal and diked wetlands.