中文摘要：

以松嫩草原自然生长状态下不同种群密度羊草生态系统为研究对象,采用野外取样与室内分析相结合的方法,研究其生物量分配、各构件有机碳含量及贮量、土壤有机碳含量及储量的变化特征。结果表明：随着种群密度的增加,羊草群落的根、茎、叶、根茎生物量以及根冠比无显著差异,而生殖构件生物量显著减少（P〈0.05）;种群密度对羊草构件的有机碳含量无显著影响;随着种群密度的增加,羊草生殖构件有机碳贮量显著降低（P〈0.05）,而对羊草非生殖构件无显著影响;种群密度影响土壤碳截获能力,低种群密度羊草生态系统碳截获能力更强,在土壤深层（20-100 cm）则更为显著（P〈0.05）。

英文摘要：

In this study, we investigated the biomass distribution, organic carbon concentration and stock of each plant component, and soil organic carbon concentration and stock of Leymus chinensis grossland ecosystems with different population densities in Songnen grassland by com- bing field sampling with laboratory analysis. Results showed that the biomass of L. chinensis re- productive components decreased obviously with the increase of population density; however, there were no significant differences in the biomass of root, stems, leaves, rhizome and shoot ratio among L. chinensis communities of different population densities. Population density had no significant effects on the organic carbon concentration of L. chinensis components. With the increase of population density, the organic carbon stock of L. chinensis reproductive components reduced significantly （ P〈0.05 ） , while the population density had no significant effects on non-reproductive components. Population density influenced the capacity of soil carbon sequestration. The low population density of L. chinensis grossland ecosystems had a higher carbon sequestration capacity than the high population density ecosystems, especially for the 20-100 cm soil depth （P〈0.05）.