T218 Groundwater Flow in Coastal Ecosystems
Monday, 6 October 2008
1:30 PM - 5:30 PM
Relation of Intertidal Salt Marsh Ecosystem Structure to Surficial Fluid and Solute Exchange
Paper number: T218-11
Program: Technical Sessions
Time: 4:00 PM – 4:20 PM
Authors
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David A. RobinsonUniversity of the West Indies, St. Augustine, N/A
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Steven M. GorelickStanford University, Stanford, CA
Abstract
This field study used electromagnetic induction geophysics to map the near-surface bulk soil conductivity (ECa) of a coastal salt marsh. ECa data reflect the effects of multiple edaphic factors of hydroecologic interest, predominantly the soil water, solute, and clay contents. Under a known change in tidal conditions, fluid versus solute exchange-dominated areas of the marsh were inferred from temporal changes in ECa. The spatially-distributed magnitudes of the water and solute exchanges were estimated using Archie's Law and measurements of soil properties. The mapped patterns of exchange were related to marsh channel geometry, microtopography, and vegetation patterns. We suggest a conceptual model of salt marsh vegetation zonation that considers multiple edaphic variables, interspecies competition, and plausible ecohydrologic feedbacks.