A coupled geomorphic and ecological model of tidal marsh evolution.
The evolution of tidal marsh platforms and interwoven channel networks cannot be addressed without treating the two-way interactions that link biological and physical processes. We have developed a 3D model of tidal marsh accretion and channel network development that couples physical sediment transport processes with vegetation biomass productivity. Tidal flow tends to cause erosion, whereas vegetation biomass, a function of bed surface depth below high tide, influences the rate of sediment deposition and slope-driven transport processes such as creek bank slumping. With a steady, moderate rise in sea level, the model builds a marsh platform and channel network with accretion rates everywhere equal to the rate of sea-level rise, meaning water depths and biological productivity remain temporally constant. An increase in the rate of sea-level rise, or a reduction in sediment supply, causes marsh-surface depths, biomass productivity, and deposition rates to increase while simultaneously causing the channel network to expand. Vegetation on the marsh platform can promote a metastable equilibrium where the platform maintains elevation relative to a rapidly rising sea level, although disturbance to vegetation could cause irreversible loss of marsh habitat.
Kirwan
Matthew L
ML
Nicholas School of the Environment and Earth Sciences, Center for Nonlinear and Complex Systems, Duke University, Durham, NC 27708, USA. mlk13@duke.edu
Murray
A Brad
AB
D005075:Biological Evolution; D018533:Biomass; D003198:Computer Simulation; D017753:Ecosystem; D019015:Geologic Sediments; D008962:Models, Theoretical; D063245:Plant Development; D013997:Time Factors; D014872:Water Movements; D053833:Wetlands