Soil respiration in Pinus tabulaeformis forest during dormant period at Huoditang forest zone in the Qinling Mountains, China

Soil CO2 efflux in forest ecosystems during dormant season is one of the key components of the forest ecosystem carbon balance. Little work has been done to quantify soil CO2 efflux in most forests in China in special time because of difficulty in taking measurements. Soil respiration in a natural secondary Pinus tabulaeformis forest at Huoditang in the Qinling Mountains was measured from October to December in 2006 by means of open-path dynamic chamber technique. Relationships of soil respiration rate (Rs) with mean soil temperature (MST) and mean volumetric soil moisture content (MVSC) in different depths (0-5 cm and 5-10 cm) were examined in the current study. We found that (1) At the same observation site (upper-part, middle-part or under-part), there were tremendous temporal and spatial variations in Rs with variation coefficients of 48.38%, 82.51% and 81.88% in October, November and December, respectively; (2) There was a significant exponent relationship between diurnal mean soil respiration rate (Fc) and diurnal mean soil temperature (DMST) when DMST > 8.5°C for both soil depths (0-5 cm and 5-10 cm) examined. The temperature sensitivity of soil respiration, known as the Q10 value, was 1.297 and 1.323 in soil depths of 0-5 cm and 5-10 cm, respectively; (3) Relationship between Rs and MVSC was complex in soil depths of 0-5 cm and 5-10 cm; (4) Soil CO2 efflux from October to December in 2006 in the experimental area was (977.37 ± 88.43) to (997.19 ± 80.73) gCm−2 (p = 0.005).