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Responses of CH4 emissions to nitrogen addition and Spartina alterniflora invasion in Minjiang River estuary,southeast of China |
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| Authors: | Xiaojie Mou Xingtu Liu Chuan Tong Zhigao Sun |
| Institution: | 1. Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, 130102, China 2. Centre of Wetlands in Sub-tropical Regions, Key Laboratory of Humid Sub-tropical Eco-geographical Process of Ministry of Education, Fujian Normal University, Fuzhou, 350007, China 3. Key laboratory of Coastal Environment Processes, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003, China |
| Abstract: | The nitrogen (N) input and Spartina alterniflora invasion in the tidal marsh of the southeast of China are increasingly serious. To evaluate CH4 emissions in the tidal marsh as affected by the N inputs and S. alterniflora invasion, we measured CH4 emissions from plots with vegetated S. alterniflora and native Cyperus malaccensis, and fertilized with exogenous N at the rate of 0 (N0), 21 (N1) and 42 (N2) g N/(m2·yr), respectively, in the Shanyutan marsh in the Minjiang River estuary, the southeast of China. The average CH4 fluxes during the experiment in the C. malaccensis and S. alterniflora plots without N addition were 3.67 mg CH4/(m2·h) and 7.79 mg CH4/(m2·h), respectively, suggesting that the invasion of S. alterniflora into the Minjiang River estuary stimulated CH4 emission. Exogenous N had positive effects on CH4 fluxes both in native and in invaded tidal marsh. The mean CH4 fluxes of N1 and N2 treatments increased by 31.05% and 123.50% in the C. malaccensis marsh, and 63.88% and 7.55% in the S. alterniflora marsh, respectively, compared to that of N0 treatment. The CH4 fluxes in the two marshes were positively correlated with temperature and pH, and negatively correlated with electrical conductivity and redox potential (Eh) at different N addition treatments. While the relationships between CH4 fluxes and environmental variables (especially soil temperature, pH and Eh at different depths) tended to decrease with N additions. Significant temporal variability in CH4 fluxes were observed as the N was gradually added to the native and invaded marshes. In order to better assess the global climatic role of tidal marshes as affected by N addition, much more attention should be paid to the short-term temporal variability in CH4 emission. |
| Keywords: | nitrogen addition CH emission tidal marsh Spartina alterniflora invasion temporal variability |
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