Soil respiration of a coniferous and broad-leaved mixed forest in Dinghushan Mountain, Guangdong Province

Field experiment was carried out to examine the soil respiration rate by using static chamber-gas chromatograph technique in a coniferous and broad-leaved forest in Dinghushan Mountain Biosphere Reserve for one year. The results show that mean annual soil respiration rate is (400±29) mg(CO₂)/(m²·h), while CO₂ from the litter decomposition accounts for 42% of the total CO₂ emission from the soil surface. Significant relationships are found between soil respiration rate and ambient air temperature, soil temperatures at different depths(the surface, 5 cm depth, 10 cm depth, 15 cm depth and 20 cm depth), which could be best described by exponential equations. The Q₁₀ values based on air temperature and soil temperature at surface, 5, 10, 15 and 20 cm depth vary from 1.92 to 2.81. The relationships between soil respiration rate and soil water content in the two observation sites vary with the soil water regime. The diurnal pattern of soil respiration rate in the rainy season is distinctly different from that in the dry season. Compared with temperate terrestrial ecosystems, this subtropical forest has a smaller diurnal variation of soil respiration rate.