Variation in tidal wetland plant diversity and composition within and among coastal estuaries: assessing the relative importance of environmental gradients
Article first published online: 19 JUL 2013
© 2013 International Association for Vegetation Science Published 2013. This article is a US Government work and is in the public domain in the USA.
Journal of Vegetation Science
Volume 25, Issue 2, pages 534–545, March 2014
How to Cite
Janousek, C. N., Folger, C. L. (2014), Variation in tidal wetland plant diversity and composition within and among coastal estuaries: assessing the relative importance of environmental gradients. Journal of Vegetation Science, 25: 534–545. doi: 10.1111/jvs.12107
- Issue published online: 24 FEB 2014
- Article first published online: 19 JUL 2013
- Manuscript Accepted: 27 JUN 2013
- Manuscript Received: 22 JUN 2012
- U.S. Environmental Protection Agency
- Hierarchical partitioning;
- NMDS ;
- Path analysis;
- Salt marsh;
- Soil salinity;
- Species accumulation curves;
- Tidal elevation;
- Tidal swamp
What is the relative importance of topographic (elevation), edaphic (soil salinity, nitrogen and particle size) and hydrologic (estuarine river flow) gradients for variation in tidal wetland plant composition and diversity?
Four Oregon estuaries: a marine-dominated lagoon, two tidal-driven bays, and a river-dominated site.
We surveyed species presence, cover and richness; and environmental factors (soil salinity, grain size, soil nitrogen and elevation) in plots in marsh and swamp. We assessed patterns of community structure and the relative importance of environmental gradients with hierarchical partitioning, ordination, species accumulation curves and path analysis.
The relative importance of measured environmental gradients on plant occurrence differed by species. Soil salinity or elevation explained the most variation in the majority of common species. Estuarine hydrology, soil nitrogen and soil clay content were usually of secondary or minor importance. Assemblage composition and species richness varied most strongly with tidal elevation. Local soil salinity also affected composition, but differences in estuarine hydrology had comparatively less effect on composition and richness. Higher-elevation wetlands supported larger species pools and higher plot-level richness; fresher wetlands had larger species pools than salt marsh but plot-level richness was relatively invariant to differences in soil salinity.
Elevation and salinity tended to exert more influence on the vegetation structure of tidal wetlands than estuarine hydrology or other edaphic variables. With relative sea-level rise expected to increase both flooding intensity and salinity exposure in future wetlands, global climate change may lead to changes in species distributions, altered floristic composition and reduced plant species richness.