Inundation depth stimulates plant‐mediated <scp>CH<sub>4</sub></scp> emissions by increasing ecosystem carbon uptake and plant height in an estuarine wetland
Mingliang Zhao, Peiguang Li, Weimin Song, Xiaojing Chu, Franziska Eller, Xiaojie Wang, Jingtao Liu, Leilei Xiao, Siyu Wei, Xinge Li, Guangxuan Han
Abstract
Abstract Plant‐mediated CH 4 emission is an important part of the ecosystem CH 4 emission from vegetated wetlands. Inundation depth may alter the potential magnitude of CH 4 releases by changing CH 4 production and plant transport, but the relationships between plant‐mediated CH 4 emissions and inundation depth are still uncertain, especially for estuarine wetlands with changeable hydrological processes. Besides, there are conflicting results regarding the role of inundation depth in plant‐mediated CH 4 emissions. Here we conducted a novel inundation depth experiment (0, 5, 10, 20, 30 and 40 cm inundation depth) dominated by Phragmites australis in the Yellow River estuary, China. Soil CH 4 emissions, ecosystem CH 4 emissions, net ecosystem CO 2 exchange (NEE), soil organic carbon (SOC) and plant traits were measured during the growing seasons of 2018, 2019 and 2020. Plant‐mediated CH 4 emissions were the difference between ecosystem CH 4 emissions and soil CH 4 emissions. The results showed that inundation depth decreased soil CH 4 emissions but increased ecosystem CH 4 emissions. Plant‐mediated CH 4 transport from Phragmites australis accounted for 99% of total ecosystem CH 4 emissions under different inundation depths. Inundation depth strongly stimulated plant‐mediated CH 4 emission from 0 to 20 cm during the growing seasons. The increased NEE enhanced plant‐mediated CH 4 emissions by altering production, suggesting that carbon components derived from photosynthetic carbon input may benefit CH 4 production. Additionally, the increased plant height promoted CH 4 emission by regulating plant transport, indicating that plant traits may play an important role in transport of CH 4 . Our findings indicated that NEE and plant height play an important role in plant‐mediated CH 4 emissions under different inundation depths in estuarine wetland. This study also highlights that hydrological regimes and plant traits are essential for the estimation of CH 4 emissions in future projections of global wetland changes. Read the free Plain Language Summary for this article on the Journal blog.