Diurnal and Seasonal Variations in Soil Respiration in a Temperate Broad-Leaved Korean Pine Forest, China

Abstract

LI-6400-09 soil CO2 flux chamber (LI-COR, NE USA) and Subtraction method were used to investigate the diurnal and seasonal variations of soil respiration and the contribution of root respiration to total soil respiration in a temperate broad-leaved Korean Pine forest ecosystem, China. Soil temperatures at 5 cm depth were recorded by Hobo thermal recorder (at 1 h interval) and year-round soil respiration and the contribution of root could be calculated based the Q10 relationship. The results indicated that: Diurnal variations of total soil respiration (TRs) and root-severed soil respiration (RRs) were highly associated with variations of soil temperature at 5 cm depth in a day. total soil respiration, root-severed soil respiration (RRs) and root respiration (Rs) followed a similar seasonal trend that varied markedly during the growing season with high rates in summer and low rates in spring and autumn, coinciding with summer wet and high temperature, and in spring and autumn, with the lower temperature. The mean rates of TRs, RRs and Rs was 3.68, 2.02 and 1.63 µmol m-2 s-1, which were 1392.63, 764.43 and 616.84 g C m-2 y-1 respectively from May to September in 2004. TRs, RRs and Rs were exponentially correlated with temperature during growing season. However, there were no correlations between soil respiration and soil volumetric moisture. The Q10 values for TRs, RRs and Rs were 2.40, 2.42 and 2.50 respectively. The root was a major component of soil respiration, accounting for from 29.3 to 58.7% of the total soil respiration from May to September in 2004. The year-round mean of TRs, RRs and Rs were 1.95, 1.07 and 0.81 µmol m-2 s-1, which were 737.94, 404.92 and 306.53 g C m-2 y-1 respectively. Root respiration contributed 41.0% to the annual total soil respiration.