Abstract: 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 combing field sampling with laboratory analysis. Results showed that the biomass of L. chinensis reproductive 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).

Key words: China, crops, greenhouse gas emissions, spatial distribution, carbon footprint