广州市红树林和滩涂湿地生态系统与大气二氧化碳交换

在生物量调查和土壤温室气体排放量测定基础上,对广州市红树林和滩涂湿地生态系统与大气CO₂交换进行研究,分析湿地植被净生产力吸收CO₂的能力和不同积水状态下(常年积水、间歇积水、无积水)湿地碳汇功能.结果表明:红树林湿地植被净生产力吸收CO₂ 33.74 t·hm^-2·a^-1,土壤排放CO₂(包括CH₄折算成CO₂的温室效应量)12.26 t·hm^-2·a^-1,湿地每年净吸收大气CO₂ 21.48 t·hm^-2,说明红树林湿地是一个强的碳汇；滩涂湿地植被净生产力吸收CO₂ 8.54 t·hm^-2·a^-1,土壤排放CO₂ 5.88 t·hm^-2·a^-1,排放CH₄ 0.19 t·hm^-2·a^-1,若按碳素折算,湿地每年吸收大气中碳素2.33 t·hm^-2,土壤排放碳素1.74 t·hm^-2包括（CH₄中的碳),系统净固定碳0.59 t·hm^-2,说明滩涂湿地是一个弱的碳汇,若将CH₄的温室效应折算成CO₂量,则土壤排放CO₂ 9.78 t·hm^-2·a^-1,排放比吸收多1.24 t·hm^-2·a^-1,对大气温室效应而言,滩涂湿地是一个弱碳源；常年积水下排放的温室气体主要是CH₄,无积水下排放的温室气体主要是CO₂；常年积水湿地碳汇功能最大,无积水湿地碳汇功能最小.

CO2 exchanges between mangrove-and shoal wetland ecosystems and atmosphere in Guangzhou.

Based on the investigation of biomass and the measurement of CO₂ and CH₄ fluxes, the CO₂ exchanges between mangrove- and shoal wetland ecosystems and atmosphere in Guangzhou were studied, and the CO₂ absorption capability of the wetlands vegetation net productivity as well as the carbon sink function of the wetlands under different waterlogged conditions (perennial, intermittent, and no water-logging) was analyzed. As for mangrove wetland ecosystem, its vegetation net productivity absorbed 33.74 t·hm^-2·a^-1 of CO₂, and soil emitted 12.26 t·hm^-2·a^-1 of CO₂ (including the greenhouse effect amount of CH₄ converted into that of CO₂), illustrating that mangrove wetland had a 21.48 t·hm^-2·a^-1 net absorption of CO₂, being a strong carbon sink. For shoal wetland ecosystem, its vegetation net productivity absorbed 8.54 t·hm^-2·a^-1 of CO₂, and soil emitted 5.88 t·hm^-2·a^-1 of CO₂ and 0.19 t·hm^-2·a^-1 of CH₄. If converting into carbon, the wetland absorbed 2.33 t C·hm^-2·a^-1, and soil emitted 1.74 t C·hm^-2·a^-1 (including the carbon in CH₄), illustrating that shoal wetland fixed 0.59 t C·hm^-2·a^-1, being a weak carbon sink. If the greenhouse effect amount of CH₄ was converted into that of CO₂, the soil emitted 9.78 t·hm^-2·a^-1 of CO₂, which was 1.24 t·hm^-2·a^-1 more than the absorption. As a result, shoal wetland was a weak carbon source. Between the two test greenhouse gases, CH₄ was the main one emitted under perennial water-logging, while CO₂ was that under no water-logging. Moreover, the wetland under perennial water-logging had the strongest carbon sink function, while that under no water-logging was in adverse.