内蒙古羊草草原凋落物分解过程中营养元素的动态

The Dynamics of Nutrients during Litter Decomposition in Leymus chinensis Grassland in Inner Mongolia,China

凋落物分解是生态系统养分循环的关键环节,作为植物体向土壤归还营养物质的主要途径,对维持生态系统的平衡具有重要的意义。以内蒙古锡林河流域的羊草草原优势种羊草（Leymus chinensis）和冰草（Agropyron cristatum）、羊草和冰草双物种、多物种混合凋落物为研究对象,采用凋落物袋法研究了4类凋落物的分解特征及营养元素动态变化过程。结果表明：多物种、双物种、羊草和冰草凋落物的分解常数分别为1.04、0.98、1.01和0.95;4类凋落物各元素表现为不同的动态变化特征,C、P、K、Mg、Ca、Cu为净释放,平均释放率在16.37%-87.43%,Fe为累积模式,累积率为140%-339%;羊草、冰草、多物种凋落物的Mn为净累积,累积率为35.07%-57.28%,而双物种凋落物的Mn为净释放,释放率仅为0.9%;羊草凋落物的Zn为净累积,累积率为70.76%,其它凋落物表现为净释放,释放率为4.09%-22.32%。混合凋落物分解存在非加性效应,在0-305 d内,羊草和冰草凋落物之间存在着抑制作用。羊草和冰草凋落物混合对C、Cu残留率起抑制作用,对Mn、Zn、Ca、Fe残留率起促进作用,而对N残留率先起促进作用后起抑制作用,对P、Mg、K的残留率无显著影响。

Litter decomposition is a key link in the process of nutrient cycling in ecosystem. As the main way to return nutrients to the soil from plants, litter decomposition has great significance on maintaining the balance of ecosystem. The decomposition characteristics and nutrient elements dynamic changes of Leymus chinensis （LC）, Agropyron cristatum （AC）, Leymus chinensis-Agropyron cristatum （LA）, and Multi-species （MT） were studied by using the litterbag method in the Xilin River Basin , Inner-Mongolia, China. The results were shown as follows： The decomposition constant of MT, LA, LC and AC was 1.04, 0.98, 1.01, 0.95 respectively. The elemental dynamic changes of 4 litters were different. C, P, K, Mg, Ca, Cu of all four litter types were net release with 16.37%-87.43% mean release amount, and Fe of all four litter types was accumulated with 140%-339% accumulative amount. Mn of LC, AC, and MT litters were net accumulation, and the accumulative amount was 35.07%-57.28%. The LA litter was net release, and its net release amount was only 0.9%. Zn of the LC litter was net accumulation and the accumulative rate was 70.76%. In addition, the Zn of other litters were net release with 4.09%-22.32% release rate. Non-additive effect existed in mixed litter. From 0 to 305 days, there was a inhibitory effect between the LC litter and AC litter. Mixed litter of the LC and AC litter had inhibitory effects on the residual rate of C and Cu, while had positive effects on Mn, Zn, Ca, Fe remaining. Litter mixing could firstly promote N remaining, and then inhibit it. It had no significant influence on the residul rate of P, Mg, K.