Biotic and abiotic factors control the geomorphic characteristics of channel networks in salt marshes

Abstract

AbstractBiotic and abiotic processes control the formation and evolution of tidal channel networks. However, which factor regulates the planimetric geometry of the network remains unclear. Here, we compare the geometric properties of tidal channel networks in 14 salt marshes along the coasts of the United States and China. Significant difference in the geometric properties of tidal channel networks was found in salt marshes dominated by different vegetation species. Physical parameters better explained these differences, while vegetation parameters had a weaker effect on the network geometry. Mean marsh elevation and tidal range were found to be the best variables to explain the variability in drainage density, mean unchanneled path length and sinuosity (R2 values range from 0.239 to 0.465), while biotic parameters (i.e., aboveground biomass, stem density, height, and diameter) were only significant predictors for less geometric properties (R2 values range from 0.005 to 0.312). We used multiple regressions to develop sample models, explaining more than 60% of the variability in mean unchanneled path length. Our findings underline the key role of physical factors in shaping tidal channel networks. We conclude that physical processes are more important than vegetation species in determining the long‐term development of tidal channels.