Impact of hydrological connectivity on the carbon sequestration and emission reduction function of salt marshes

The hardened artificial structures such as seawalls and breakwaters have impended hydrological connectivity in salt marshes, affecting vegetation restoration and associated ecological functions. Many ecological projects have been carried out to restore wetlands through hydrological regulation. However, most studies have focused on the effects of hydrological conditions on biodiversity, while the effects on the function of carbon sequestration and emission reduction are relatively lacking. This study conducted a large-scale controlled experiment in Yingwuzhou wetland located in northern Hangzhou Bay to explore the effects of hydrological connectivity on plant growth, greenhouse gas emissions and soil organic carbon content in salt marshes. Results indicated that in hydrological connection area, the plant height, biomass, and net primary productivity of Phragmites australis were significantly greater than those in hydrostatic area. While the annual CO₂ absorption flux showed no significant difference between the two study areas, the CH₄ emission flux in the flow area was significantly lower than that in the hydrological connection area. It suggests that hydrological connectivity can promote the growth of Phragmites australis and increase net primary productivity, while effectively inhibiting CH₄ emissions the conectivity can promote the carbon sequestration and emission reduction functions of the salt marshes.