Methane Emissions from Subtropical and Tropical Mangrove Ecosystems in Taiwan

• Main Authors: Chiao-Wen Lin, Yu-Chen Kao, Meng-Chun Chou, Hsin-Hsun Wu, Chuan-Wen Ho, Hsing-Juh Lin
• Format: Article
• Language: English
• Published: MDPI AG 2020-04-01
• Series: Forests
• Subjects: <i>Avicennia marina</i>; <i>Kandelia obovata</i>; greenhouse gas; methane; pneumatophore; soil
• Online Access: https://www.mdpi.com/1999-4907/11/4/470

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 (<i>Kandelia obovata</i>) and tropical (<i>Avicennia marina</i>) 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 <i>Avicennia</i> mangroves. However, no seasonal variation in CH₄ flux was observed in the <i>Kandelia</i> mangroves. CH₄ fluxes were significantly higher in the mangrove soils of <i>Avicennia</i> than in the adjoining mudflats; this trend, however, was not necessarily recapitulated at <i>Kandelia</i>. The results of multiple regression analyses show that soil water and organic matter content were the main factors regulating the CH₄ fluxes in the <i>Kandelia</i> mangroves. However, none of the soil parameters assessed show a significant influence on the CH₄ fluxes in the <i>Avicennia</i> mangroves. Since pneumatophores can transport CH₄ from anaerobic deep soils, this study suggests that the pneumatophores of <i>Avicennia marina</i> 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.