Winter harvesting reduces methane emissions and enhances blue carbon potential in coastal phragmites wetlands

Ying Huang; Qingyu Jia; Jiangtao Wang; Sung-Ching Lee; Xianglan Li; Xiuzhen Li; Jianwu Tang

doi:10.1016/j.scitotenv.2024.173380

Winter harvesting reduces methane emissions and enhances blue carbon potential in coastal phragmites wetlands

Sci Total Environ. 2024 Aug 15:938:173380. doi: 10.1016/j.scitotenv.2024.173380. Epub 2024 May 24.

Authors

Ying Huang¹, Qingyu Jia², Jiangtao Wang³, Sung-Ching Lee⁴, Xianglan Li⁵, Xiuzhen Li⁶, Jianwu Tang⁶

Affiliations

¹ State Key Laboratory of Estuarine and Coastal Research, Center for Blue Carbon Science and Technology, East China Normal University, Shanghai, China; Yangtze Delta Estuarine Wetland Ecosystem Observation and Research Station, Ministry of Education & Shanghai Science and Technology Committee, Shanghai, China. Electronic address: yhuang@sklec.ecnu.edu.cn.
² Institute of Atmospheric Environment, China Meteorological Administration, Shenyang, China.
³ Institute of Eco-Chongming, East China Normal University, Shanghai, China.
⁴ Department Biogeochemical Integration, Max Planck Institute for Biogeochemistry, Jena, Germany.
⁵ State Key Laboratory of Remote Sensing Science, College of Global Change and Earth System Science, Beijing Normal University, Beijing, China.
⁶ State Key Laboratory of Estuarine and Coastal Research, Center for Blue Carbon Science and Technology, East China Normal University, Shanghai, China; Yangtze Delta Estuarine Wetland Ecosystem Observation and Research Station, Ministry of Education & Shanghai Science and Technology Committee, Shanghai, China; Institute of Eco-Chongming, East China Normal University, Shanghai, China.

PMID: 38797417
DOI: 10.1016/j.scitotenv.2024.173380

Abstract

Enhancing the ability of coastal blue carbon to accumulate and store carbon and reduce net greenhouse gas emissions is an essential component of a comprehensive approach for tackling climate change. The annual winter harvesting of Phragmites is common worldwide. However, the effects of harvesting on methane (CH₄) emissions and its potential as an effective blue carbon management strategy have rarely been reported. In this study, the effects of winter Phragmites harvesting on the CH₄ and carbon dioxide (CO₂) fluxes and the underlying mechanisms in coastal Phragmites wetlands were investigated by comparing the eddy covariance flux measurements for three coastal wetlands with different harvesting and tidal flow conditions. The results show that harvesting can greatly reduce the CH₄ emissions and the radiative forcing of CH₄ and CO₂ fluxes in coastal Phragmites wetlands, suggesting that winter Phragmites harvesting has great potential as a nature-based strategy to mitigate global warming. The monthly mean CH₄ fluxes were predominantly driven by air temperature, gross primary productivity, and latent heat fluxes, which are related to vegetation phenology. Additionally, variations in the salinity and water levels exerted strong regulation effects on CH₄ emissions, highlighting the important role of proper tidal flow restoration and resalinization in enhancing blue carbon sequestration potential. Compared with the natural, tidally unrestricted wetlands, the CH₄ fluxes in the impounded wetland were less strongly correlated with hydrometeorological variables, implying the increased difficulties of predicting CH₄ variations in impounded ecosystem. This study facilitates the improved understanding of carbon exchange in coastal Phragmites wetlands with harvesting or impoundment, and provides new insights into effective blue carbon management strategies beyond tidal wetland restoration for mitigating the effects of climate change.

Keywords: Blue carbon; Coastal wetland; Eddy covariance; Harvest; Methane emission; Net ecosystem exchange.