三江平原草甸湿地土壤呼吸和枯落物分解的CO2释放

利用静态箱-碱液吸收法研究了三江平原草甸湿地土壤呼吸和枯落物分解的CO₂释放速率，讨论了影响CO₂释放的环境因素，估算了枯落物分解的CO₂释放对于总释放的贡献。结果表明，生长季，小叶章沼泽化草甸和小叶章湿草甸各部分CO₂释放均具有明显的时间变化特征，温度和水分是重要制约因素。两类草甸湿地的平均土壤呼吸速率分别为4.33g•m^-2•d^-1和6.15g•m^-2•d^-1，枯落物分解的CO₂平均释放速率分别为1.76g•m^-2•d^-1和3.10g•m^-2•d^-1，枯落物分解的CO₂释放占总释放量的31%和35%，说明在碳素由地上植物碳库转移到地下土壤碳库的过程中，湿地枯落物是一个不可忽略的碳损失源。

CO2-release rate of soil respiration and litter decomposition of meadow marshes in Sanjiang Plain

Static-chamber in field and alkaline absorption methods were used to measured the CO₂-release rates of soil respiration and litter decomposition of meadow marshes in Sanjiang Plain. The effects of environmental factors on CO₂-release were discussed and then the contribution of the litter decomposition to the total CO₂-release was estimated. Two types of D. angustifolia meadow (XZ and XD) were selected to synchronously observe the CO₂ release and the temperatures of air and soil in the growing season. The results showed that the CO₂ release temporally varied (p<0.05). The rates of soil respiration in the XZ and XD were higher in July and August and the daily averages were 6.08g•m-2•d^-1 and 9.26g•m-2•d^-1, respectively. However the rates of CO₂-release from litter decomposition were higher in June and the daily averages were 1.76g m-2•d^-1 and 3.10g•m-2•d^-1, respectively. The results also showed that the total CO₂-release and release from litter decomposition were different between two sites of XZ and XD (p<0.05). There were a significantly exponential relationships between the soil respiration and soil temperature (p1<0.01, p2<0.05) and between the total CO₂-release and air temperature (p1<0.01, p2<0.01) in sites of XZ and XD. Multi-analysis showed that temperatures of air and soil combined with monthly accumulative precipitation could effectively explain the changes of the total CO₂-release (R12=0.967, R22=0.741) and soil respiration (R12=0.548, R22=0.893) in sites of XZ and XD, respectively. Based on the rates of CO₂-release from different carbon pools, the contribution of litter decomposition to the total CO₂-release was estimated to be 31% and 35% in the XZ and XD, respectively. This study demonstrated that during the transferring process from the plant carbon pool to the soil carbon pool, the litter in marsh as important release sources of carbon should not be neglected.