Spartina alterniflora invasion alters soil bacterial communities and enhances soil N 2 O emissions by stimulating soil denitrification in mangrove wetland

• Published in: The Science of the total environment Vol. 653; p. 231
• Main Authors: Gao, Gui-Feng, Li, Peng-Fei, Zhong, Jia-Xin, Shen, Zhi-Jun, Chen, Juan, Li, Yun-Tao, Isabwe, Alain, Zhu, Xue-Yi, Ding, Qian-Su, Zhang, Shan, Gao, Chang-Hao, Zheng, Hai-Lei
• Format: Journal Article
• Language: English
• Published: Netherlands 25-02-2019
• Subjects: Soil NO emissions; Mangrove; Potential denitrification; Spartina alterniflora; Bacterial community
• ISSN: 1879-1026
• DOI: 10.1016/j.scitotenv.2018.10.277

Chinese mangrove, an important ecosystem in coastal wetlands, is sensitive to the invasive alien species Spartina alterniflora. However, the effects of the S. alterniflora invasion on mangrove soil N
O emissions and the underlying mechanisms by which emissions are affected have not been well studied. In this study, the N
O emitted from soils dominated by two typical native mangroves (i.e. Kandelia obovata: KO; Avicennia marina: AM), one invaded by S. alterniflora (SA), and one bare mudflat (Mud) were monitored at Zhangjiang Mangrove Estuary (where S. alterniflora is exotic). Together with soil biogeochemical properties, the potential denitrification rate and the composition of soil bacterial communities were determined simultaneously by
NO
tracer and high-throughput sequencing techniques, respectively. Our results showed that S. alterniflora invasion significantly (p < 0.05) increases soil N
O emissions by 15-28-fold. In addition, isotope results revealed that the soil potential denitrification rate was significantly (p < 0.05) enhanced after S. alterniflora invasion. Moreover, the S. alterniflora invasion significantly (p < 0.05) decreased soil bacterial α-diversity and strongly modified soil bacterial communities. Indicator groups strongly associated with S. alterniflora were Chloroflexia, Alphaproteobacteria, and Bacilli, each of which was abundant and acts as connector in the co-occurrence network. FAPROTAX analysis implied that the S. alterniflora invasion stimulated soil denitrification and nitrification while depressing anaerobic ammonium oxidation (anammox) and dissimilatory nitrate reduction to ammonium (DNRA). Redundancy analysis (RDA) found that soil organic matter (SOM) and pH were the most important environmental factors in altering soil bacterial communities. Taken together, our results imply that the S. alterniflora invasion in mangrove wetlands significantly stimulates soil denitrification and N
O emissions, thereby contributing N
O to the atmosphere and contributing to global climate change.