ALBERT

Description: Aims Soil CO 2 emission from steppes is affected by soil properties and vegetation in different successional stages. Primary and secondary succession of plants frequently occurred at the meadow steppe in Songnen Plain, Northeast China, which indicates the large uncertainty associated with CO 2 emission in this environment. This study aims to investigate the temporal variations of soil respiration (Rs) and the effect of plant succession on cumulative soil CO 2 emission during the growing season. Methods Using a LI-6400 soil CO 2 flux system, Rs of five vegetation types which represented different stages of plant succession in meadow steppes of Songnen Plain, China, was investigated during the growing seasons of 2011 and 2012. Important Findings Soil temperature (Ts) was the dominant controlling factor of Rs, which could explain ~64% of the change in CO 2 fluxes. The Q 10 values of Rs were ranged from 2.0 to 6.7, showing a decreasing trend with the plant successional stages. The cumulative CO 2 emission increased with the degree of vegetation succession and it averaged to 316±6g C m –2 (ranges: 74.8±6.7 to 516.5±11.4g C m –2 ) during the growing season. The magnitude of soil CO 2 emission during the growing season was positively correlated with aboveground plant biomass, soil organic carbon content and mean soil water content, while negatively linked to mean Ts, pH, electrical conductivity and exchangeable sodium percentages. The results implied that soil CO 2 emission increased with the development of plant communities toward more advanced stages. Our findings provided valuable information for understanding the variations of CO 2 emission in the process of vegetation succession.