尕海湿地不同植被退化阶段凋落物分解及其有机碳动态

Litter Decomposition and Dynamics of Organic Carbon in Degraded Vegetation of Gahai Wetland

以甘南尕海湿地不同植被退化阶段的泥炭沼泽和沼泽化草甸为研究对象,通过2013,2014两年凋落物试验分析,研究了不同植被退化过程中凋落物的分解速率及有机碳动态变化特征。结果表明:随着植被退化演替,凋落物有机碳浓度、碳绝对含量和分解速率显著下降(p<0.05)。分解速率从6—9月随时间变化均呈现下降趋势,相应的分解速率在0.001 3~0.009/d之间,分解速率最大的为2013年泥炭沼泽未退化PI(0.009/d),最小为2014年沼泽化草甸中度退化SⅢ(0.001 3/d)。泥炭沼泽凋落物中有机碳平均浓度未退化PI(515.07g/kg)>退化PⅡ(489.62g/kg),沼泽化草甸凋落物有机碳平均浓度未退化SI(541.26g/kg)>轻度退化SⅡ(488.28g/kg)>中度退化SⅢ(456.01g/kg),且两年的凋落物碳绝对含量均减小,即发生净释放;凋落物分解速率及有机碳浓度、碳绝对含量都随植被退化加深而减小。

In this study,peat swamps and swamp meadows with different degrees of degradation in Gannan Gahai wetland area were selected to explore the decomposition rate and the organic carbon content of litter during different vegetation degradation process in two years,based on field sampling and laboratory analysis.The results showed that the organic carbon content and decomposition rate of litter decreased significantly with the degradation of vegetation(p<0.05).The decomposition rate decreased from June to September,and the maximum of it was observed in the undegraded peat swamp PI(0.009/d)in 2013,and the minimum was found in the moderately degenerate swamp meadow SⅢ(0.001 3/d)in 2014.Average content of organic carbon in litter of peat swamp decreased in the order:ungraded PI(515.07 g/kg)>degraded PⅡ(489.62 g/kg),mean concentration of organic carbon in litter of swamp meadow decreased in the order:ungraded SI(541.26 g/kg)>lightly degraded SⅡ(488.28 g/kg)>moderately degraded SⅢ(456.01 g/kg),and the absolute carbon content of litter decreased in the two years,indicating that it occurred net release.The litter decomposition rate,organic carbon content and absolute carbon content decreased with the vegetation degradation process.