The Relationship of Salt Marsh Vegetation Lateral Obstruction to Vegetation Morphology
Abstract
Vegetation in salt marshes attenuates wave energy while influencing sediment accretion and turbulence in the water column. Modeling the interaction of waves and vegetation has been typically approached through an empirical coefficient of drag variable that is calibrated for a given set of biologic conditions dependent upon stem density and diameter. This method oversimplifies the complexity of vegetation morphology while also requiring assumptions to be made about the vegetation itself (uniform stem diameters for all stems) and leads to large uncertainty in the drag coefficient. As an alternative to the uniform vegetation model, we focus on the variation of the lateral obstruction of vegetation. This measure of cover in the vertical plane over a given horizontal distance is useful for presenting and quantifying complex vegetation morphology from live, in situ, vegetation. We compare the lateral obstruction of two common Pacific Northwest estuarine species, threesquare bulrush (Schoenoplectus pungens), and Lyngbye's sedge (Carex lyngbyei), to their in situ morphologic characteristics (density, height, diameter, aboveground biomass) over varying horizontal distances. From this, the amount of lateral obstruction is used to determine an estimate of the morphologic characteristics of the species in other environments and vice versa, therefore providing a means of making more accurate comparisons between and among species. We anticipate that this method will improve the calibration of the coefficient of drag variable in wave attenuation equations by incorporating the vertical variation of plant density.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFMOS31B1718L
- Keywords:
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- 1890 HYDROLOGY Wetlands;
- 4235 OCEANOGRAPHY: GENERAL Estuarine processes;
- 4299 OCEANOGRAPHY: GENERAL General or miscellaneous;
- 4894 OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL Instruments;
- sensors;
- and techniques