漳江口不同潮滩秋茄树干CH_4传输速率与呼吸速率

Rate of Methane Transport and Respiration from the Stem of Mangrove Kandelia obovata at Different Part of Intertidal Zone in Zhangjiang River Estuary

树干对红树林湿地CH_4和CO_2的排放有重要影响.为研究红树林湿地温室气体排放机制及其影响因子,于2017年9月利用树干静态箱-气相色谱仪法,以漳江口秋茄(Kandelia obovata)红树林为研究对象,探讨不同潮滩(中、高潮滩)下秋茄树干CH_4传输速率和呼吸速率的特征.结果表明:①中潮滩秋茄树干CH_4传输速率〔(91. 19±16. 63)μg/(m2·h)〕显著大于高潮滩〔(0. 71±0. 24)μg/(m2·h)〕(P<0. 001),而中、高潮滩秋茄树干呼吸速率无显著性差异(P>0. 05).②秋茄树干CH_4传输速率受土壤孔隙水的影响较大,与土壤孔隙水中c(CH_4)呈极显著正相关(P<0. 01),与孔隙水中ρ(DON)呈极显著负相关(P<0. 01).③秋茄树干呼吸速率与胸径大小呈极显著正相关(P<0. 01),并呈极显著性幂函数回归关系(P<0. 001),而树干CH_4传输速率不受胸径大小的影响.研究显示,与红树林湿地的空间异质性相比,植物特征对树干呼吸速率的影响更为显著;相反,对于树干CH_4传输速率,空间异质性的影响比植物特征的影响更为显著.

Trunk plays an important role in mediating methane emissions and respiration in the mangrove wetlands. To better understand the pattern and control of greenhouse gas effluxes in mangrove wetlands,the methane transport rates and respiration rates were measured in the trunk of Kandelia obovata in Zhangjiang River Estuary,southeast China. Using closed static chambers,our results showed that the trunk methane transport rates were significantly higher in the middle intertidal zone((91. 19 ± 16. 63)μg/(m^2·h)) and high intertidal zone((0. 71±0. 24)μg/(m^2·h))(P<0. 001). By contrast,the respiration rates were comparable between the two intertidal zones. The methane transport rates of trunk were in accordance with the soil moisture,while the concentration of dissolved methane was positively and negatively correlated with pore water c(CH4) and ρ(DON),respectively. The trunk respiration rates of Kandelia obovata were determined by DBH(diameter at breast height),while the rates of trunk methane transport were not affected by DBH. The traits of plant growth had more pronounced influence on trunk respiration rates compared to the spatial heterogeneity of mangrove wetlands,and vice versa on the trunk methane transport rates.