Tidal restriction likely has greater impact on the carbon sink of coastal wetland than climate warming and invasive plant
- 1China University of Geosciences (Wuhan), Wuhan, China (541646172@qq.com)
- 2Laboratory for Marine Geology, Laoshan Laboratory, Qingdao, China
- 3Chinese Academy of Geological Sciences, Beijing, China
- 4Key Laboratory of Coastal Wetlands Biogeosciences, Qingdao Institute of Marine Geology, China Geologic Survey, Qingdao, China
- 5Institute of Marine Science and Technology, Shandong University, Qingdao, China
- 6U.S. Geological Survey, Wetland and Aquatic Research Center, Lafayette, LA, USA
- 7Department of Biology and Center for Biodiversity and Ecosystem Stewardship, Villanova University, Villanova, PA, USA
- 8Department of Bioscience, Aarhus University, Aarhus, Denmark
- 9Department of Environmental Sciences, School of the Coast and Environment, Louisiana State University, Baton Rouge, LA, USA
Aims Coastal salt marshes are productive ecosystems that are highly efficient carbon sinks, but there is uncertainty regarding the interactions among climate warming, plant species, and tidal restriction on C cycling.
Methods Open-top chambers (OTCs) were deployed at two coastal wetlands in Yancheng, China, where native Phragmites australis (Phragmites) and invasive Spartina alterniflora (Spartina) were dominant, respectively. Two study locations were set up in each area based on difference in tidal action. The OTCs achieved an increase of average daytime air temperature of ~1.11–1.55 °C. Net ecosystem CO2 exchange (NEE), ecosystem respiration (Reco), CH4 fluxes, aboveground biomass and other abiotic factors were monitored over three years.
Results Warming reduced the magnitude of the radiative balance of native Phragmites, which was determined to still be a consistent C sink. In contrast, warming or tidal flooding presumably transform the Spartina into a weak C source, because either warming-induced high salinity reduced the magnitude of NEE by 19% or flooding increased CH4 emissions by 789%. Remarkably, native Phragmites affected by tidal restrictions appeared to be a consistent C source with the radiative balance of 7.11–9.64 kg CO2-eq m–2 yr–1 because of a reduction in the magnitude of NEE and increase of CH4 fluxes.
Conclusions Tidal restrictions that disconnect the tidal hydrologic connection between the ocean and land may transform coastal wetlands from C sinks to C sources. This transformation may potentially be an even greater threat to coastal carbon sequestration than climate warming or invasive plant species in isolation.
How to cite: Zhou, P., Ye, S., Xie, L., W. Krauss, K., Pei, L., K. Chapman, S., Brix, H., A. Laws, E., Yuan, H., Yang, S., Ding, X., and Xie, S.: Tidal restriction likely has greater impact on the carbon sink of coastal wetland than climate warming and invasive plant, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1293, https://doi.org/10.5194/egusphere-egu24-1293, 2024.
