Methane Emissions from Subtropical and Tropical Mangrove Ecosystems in Taiwan: Fid-Bau Portal

Methane Emissions from Subtropical and Tropical Mangrove Ecosystems in Taiwan

Chiao-Wen Lin / Yu-Chen Kao / Meng-Chun Chou / Hsin-Hsun Wu / Chuan-Wen Ho / Hsing-Juh Lin

Mangroves are one of the blue carbon ecosystems. However, greenhouse gas emissions from mangrove soils may reduce the capacity of carbon storage in these systems. In this study, methane (CH₄) fluxes and soil properties of the top 10 cm layer were determined in subtropical (Kandelia obovata) and tropical (Avicennia marina) mangrove ecosystems of Taiwan for a complete seasonal cycle. Our results demonstrate that CH₄ emissions in mangroves cannot be neglected when constructing the carbon budgets and estimating the carbon storage capacity. CH₄ fluxes were significantly higher in summer than in winter in the Avicennia mangroves. However, no seasonal variation in CH₄ flux was observed in the Kandelia mangroves. CH₄ fluxes were significantly higher in the mangrove soils of Avicennia than in the adjoining mudflats; this trend, however, was not necessarily recapitulated at Kandelia. The results of multiple regression analyses show that soil water and organic matter content were the main factors regulating the CH₄ fluxes in the Kandelia mangroves. However, none of the soil parameters assessed show a significant influence on the CH₄ fluxes in the Avicennia mangroves. Since pneumatophores can transport CH₄ from anaerobic deep soils, this study suggests that the pneumatophores of Avicennia marina played a more important role than soil properties in affecting soil CH₄ fluxes. Our results show that different mangrove tree species and related root structures may affect greenhouse gas emissions from the soils.