Variation of soil respiration and its environmental factors in Hulunber meadow steppe

In order to understand the variations of soil respiration with the controlling environmental factors, continuous monitoring was carried out in Hulunber meadow steppe by an automated chamber system, LI-8150, from 2009 to 2011. The results showed that soil respiration exhibited an apparent diurnal variation and seasonal dynamics. Diel maximum soil respiration often appeared between 13:00 and 14:00, while the minimum occurred between 4:00 and 5:00 in the morning. Soil respiration in the growing season from May to September was higher than that in the non-growing season. The peak value often occurred in July and August and the lowest was close to zero in winter. Soil respiration had a significant exponential relationship with soil temperature at 5 cm depth (P < 0.01), which could explain the 86.1–91.1% variation in soil respiration. A significant linear relationship was indicated between soil respiration and soil water content at 10 cm depth (P < 0.05). Soil respirations in 2009, 2010 and 2011 were estimated to be 465.0 gC m−2, 539.2 gC m−2 and 553.2 gC m−2 respectively. In addition, the temperature sensitivities of soil respiration (Q10) were calculated as 3.32, 3.55 and 4.05, respectively. The value of Q10 could cause a lower evaluation derived from observation in a short time, such as considering only the growing season. Field observation of soil respiration should cover all the possible time in the whole year, including the growing and non-growing seasons.