Patterns and controls of temperature sensitivity of soil respiration in a meadow steppe of the Songnen Plain, Northeast China.

Quantifying the temporal and spatial patterns of temperature sensitivity (Q10) of soil respiration (Rs) as well as its controlling factors is critical to reveal the response the soil ecological processes to global warming and improve carbon budget estimations at a regional scale. The seasonal and annual variations in the temperature response of Rs were assessed during the two growing seasons in 2011 and 2012 in four different vegetation sites in a meadow steppe of the Songnen Plain, China. The Q10 values across all sites exhibited significant seasonal variations with a minimum value (1.81-2.34) occurring during summer and a peak value (3.82-4.54) occurring in either spring or autumn. The mean seasonal Q10 values showed no significant differences among the four different vegetation types. On the annual scale, however, the Chloris virgata site had significantly higher annual Q10 values (3.67-4.22) than the other three community sites in 2011 and 2012 and over the two years (2.01-3.67), indicating that the response of the Rs to climate warming may vary with vegetation type. The soil temperature and moisture had interactive effects on the variations of Q10 values. Soil temperature was the dominant factor influencing Q10 values, while soil moisture was an additional contributor to the variations of Q10. Due to the significant temporal and spatial variations in soil respiration response to temperature, acclimation of Rs to temperature variation should be taken into account in forecasting future terrestrial carbon cycle and its feedback to global warming.