Responses of photosynthetic characteristics of to simulated warming in salt marshes of the Yellow Sea and Bohai Sea, China.

Coastal wetlands are highly efficient in blue carbon sequestration. The impacts of climate warming on photosynthetic rates and light response characteristics of wetland plants would change the magnitude of carbon sequestration in coastal wetlands. We constructed warming observation stations in () wetlands located in the Yellow River Delta in Dongying with dry climate, and in Yancheng by the Yellow Sea with wet climate. By using a Li-6800 photosynthesis system, we investigated the responses of simulated warming on photosynthetic characteristics of in both wetlands, and compared the difference between months (June and August) in Dongying wetland. The results showed the photosynthetic rates of were higher in June than in August. Warming increased net photosynthetic rate (), transpiration rate (), stomatal conductance () and intercellular carbon dioxide concentration () in the two months, but the variability of to warming was lower in August. The and water use efficiency (WUE) of in the Yancheng wetland were higher than Dongying wetland, and the maximum net photosynthetic rate (), light saturation point (LSP), apparent quantum efficiency (AQY), and dark respiration rate () of the former responded more positively to warming. The values of AQY, LSP and of in the Yancheng wetlands were increased by 16.7%, 53.6% and 30.3%, respectively, in the warming plots. Our results suggested that warming could improve the utilization efficiency of weak light, the adaptability to strong light and photosynthetic potential of under rainy and humid conditions. This study is of importance for accurately quantifying carbon sequestration of coastal wetlands at the regional and seasonal scales in the context of climate warming.