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Spatial patterns of composition in tidal wetland plant and algal assemblages in Oregon: Implications for wetland vulnerability to sea-level rise
Citation:
JANOUSEK, C. N. AND C. FOLGER. Spatial patterns of composition in tidal wetland plant and algal assemblages in Oregon: Implications for wetland vulnerability to sea-level rise. Presented at Pacific Estuarine Research Society Meeting, Anacortes, WA, April 12 - 14, 2012.
Impact/Purpose:
Plants and algae mediate important ecosystem processes in coastal marshes and swamps.
Description:
Plants and algae mediate important ecosystem processes in coastal marshes and swamps. These assemblages are structured in part by estuarine environmental gradients such as tidal elevation and salinity. Such gradients are likely to change with sea-level rise (SLR) due to global climate change. We used data from four Oregon estuaries to (1) quantify vascular plant and algal variation within and between estuaries, (2) determine the distribution of plants and algae along elevation and salinity gradients, and (3) assess potential vulnerabilities of wetland vegetation to SLR. We found that plant assemblages tended to vary more within individual estuaries than among them. Plant composition differed especially between low estuarine marsh and palustrine tidal marsh. Tidal elevation strongly affected macroalgal abundance, sediment chlorophyll a, plant composition, and plant diversity; salinity also appeared to structure wetland primary producers. Our preliminary findings suggest that SLR may shift wetlands to more algal-dominated habitats and reduce plant diversity absent sufficient accretion and/or lateral migration of intertidal habitat. If salinity intrusion accompanies SLR, wetland vegetation may be able to tolerate elevated salinity throughout much of the estuary, but species in fresher tidal wetlands may be negatively impacted.