Abstract: The present study was to probe into the changes and its influencing factors of litter decomposition process in desertified steppe of Ningxia. The litter of L. secalinus, L. bicolor and their mixture were selected using litterbag method of different mesh sizes. The results showed:the decomposition rates of L. secalinus, L. bicolor and their mixture wcere found to increase significantly at the early stage,and to fluctuate smoothly at the mediate stage in all three types of meshes,while there were significant differences at the late stage in the three types of meshes. At the stage of 70 d and 210 d,the plant litter decomposition rates in 4-mm-mesh and 2-mm-mesh litterbags were found to follow an order of mixture > L. bicolor > L. secalinus. However,that in 0.01-mm-mesh litterbags were found to follow an order of mixture > L. bicolor > L. secalinus at the stage of 210 d only. At the stage of 140 d,only in 4-mm-mesh litterbags and at the stage of 280 d,in 2-mm-mesh and 0.01-mm-mesh litterbags,there were significant differences in three treatments litter decomposition process. At the rate of 50% and 95%,the time for decomposition of L. secalinus and their mixture litter was found to increase,whereas that of L. bicolor litter was found to reduce along with the reduced mesh size. It was concluded that the stage of 210 d was an important threshold for the significant changes in the litter decomposition rate of three litter treatments. There were significant differences in the litter decomposition process in the three litter treatments. The soil faunal distributions and related humid and temperature conditions were the key factors driving the litter decomposition process of dominant plants in desertified steppe of Ningxia.

Key words: Plant species, Litter, Decomposition rate, Litterbag in mesh, Desertified steppe

摘要： 为明确宁夏荒漠草原植物枯落物分解规律，以赖草（Leymus secalinus）、胡枝子（Lespedeza bicolor）及其混合物枯落物为研究对象，采用网孔分解袋法，调查了不同处理植物枯落物分解率及其影响因素。结果显示：植物枯落物分解率均呈现出前期显著增加、中期平缓变化趋势，但后期受网孔影响较大。70 d和210 d时，4 mm和2 mm网孔中分解率均表现为混合物最高，胡枝子居中，而赖草最低；但在0.01 mm网孔中，仅210 d分解率表现为混合物和胡枝子较高，而赖草最低。并且，140 d时仅4 mm网孔、280 d时仅2 mm和0.01 mm网孔中3种处理植物枯落物分解率呈现出显著差异性。分解50%和95%所需时间，随网孔减小，赖草和混合物枯落物则延长，而胡枝子枯落物则缩短。研究表明，210 d是3种处理枯落物分解率显著变化的重要节点。不同处理植物枯落物分解过程显著不同，并且受到不同土壤动物类群分布及温湿条件的深刻影响。

关键词: 植物种, 枯落物, 分解率, 网孔分解袋, 荒漠草原