Alteration of nitrogen sink and emission by vegetation distribution in a wetland with significant change in water level

Huazu Liu; Qiu Jin; Xiaoguang Xu; Wei Yang; Megumu Fujiabayashi; Junxiao Luo; Zhexin Li; Chuanqiao Zhou; Pingyin Shu; Wei Li

doi:10.1016/j.jenvman.2024.123920

Alteration of nitrogen sink and emission by vegetation distribution in a wetland with significant change in water level

J Environ Manage. 2024 Dec 27:373:123920. doi: 10.1016/j.jenvman.2024.123920. Online ahead of print.

Authors

Huazu Liu¹, Qiu Jin², Xiaoguang Xu³, Wei Yang⁴, Megumu Fujiabayashi⁵, Junxiao Luo⁴, Zhexin Li⁴, Chuanqiao Zhou⁶, Pingyin Shu⁴, Wei Li⁷

Affiliations

¹ Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing, 400045, China; Department of Ecological Sciences and Engineering, Chongqing University, Chongqing, 400045, China; Department of Urban and Environmental Engineering, Graduate School of Engineering, Kyushu University, Fukuoka, 8190395, Japan.
² State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Nanjing Hydraulic Research Institute, Nanjing, 210029, China; College of Agricultural Science and Engineering, Hohai University, Nanjing, 210098, China.
³ School of Environment, Nanjing Normal University, Nanjing, 210023, China.
⁴ Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing, 400045, China; Department of Ecological Sciences and Engineering, Chongqing University, Chongqing, 400045, China.
⁵ Department of Urban and Environmental Engineering, Graduate School of Engineering, Kyushu University, Fukuoka, 8190395, Japan.
⁶ Department of Transdisciplinary Science and Engineering, Tokyo Institute of Technology, Tokyo, 1528550, Japan.
⁷ Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing, 400045, China; Department of Ecological Sciences and Engineering, Chongqing University, Chongqing, 400045, China. Electronic address: [email protected].

PMID: 39731950
DOI: 10.1016/j.jenvman.2024.123920

Abstract

In wetlands, hydrological conditions drive plant community distribution, forming vegetation zones with plant species and material cycling. This mediates nitrogen migration and N₂O emissions within wetlands. Five vegetation zones in a large wetland were studied during flooding and drought periods. Zones including mud flat, nymphoides, phalaris, carex, and reeds, distributed sequentially with increasing water level change rate. Carbon and nitrogen densities were higher during drought period. When sediments alternated between source and sink roles annually, N₂O emissions varied significantly with zones and water levels. Emission flux decreased with higher C:N ratio in sediments, approximating a threshold at 0.23 μg m^-2 h^-1 when C:N ratio exceeded 25. Denitrifying nirS and nirK genes and anammox hzsB gene varied significantly with water level, most prominently in mud flat and nymphoides zones. Plant distribution under hydrological conditions alters soil stoichiometric ratio, influencing N₂O emissions and microbial communities across vegetation zones. Therefore, in freshwater wetlands, hydraulic regulation and reduction in prolonged flooding would be an effective strategy for mitigation of greenhouse gas emissions.

Keywords: Anammox; Denitrification; Greenhouse gases; Stoichiometry; Vegetation distribution; Water level.