亚热带米老排和杉木人工林土壤呼吸季节动态及其影响因子

Seasonal Dynamics of Soil Respiration and Its Affecting Factors in Subtropical Mytilaria laosensis and Cunninghamia lanceolata Plantations

研究我国亚热带地区杉木人工林采伐迹地上营造的19年生米老排人工林和杉木人工林土壤呼吸及其影响因子。结果表明:米老排人工林土壤呼吸速率的年均值为2.95μmolCO2·m-2s-1,显著高于杉木人工林的2.37μmolCO2·m-2s-1;米老排人工林土壤呼吸的Q10值为1.83,显著低于杉木人工林的1.99;2种林分土壤呼吸均呈现明显的季节动态,主要受土壤温度的驱动,土壤温度能分别解释米老排和杉木人工林土壤呼吸速率变化的77.0%和81.6%;回归分析显示,2种林分土壤呼吸速率与凋落物量、细根生物量、土壤有机碳含量、轻组有机碳含量、微生物生物量碳含量和可溶性有机碳含量均显著相关;逐步线性回归分析表明,土壤呼吸速率与凋落物量和土壤微生物生物量碳含量的关系最密切;树种间凋落物量和土壤微生物生物量的差异是导致米老排人工林土壤碳排放速率高于杉木人工林的重要原因。

We investigated monthly soil respiration （Rs） and the affecting factors under 19-year-old Mytilaria laosensis and Cunninghamia lanceolata plantations replanted in a C. lanceolata woodland slash in subtropical China. The results showed that the average annual Rs rates were 2.95 μmolCO2 ·m -2 s -1 under M. laosensis plantations and 2. 37 μmolCO2 · m -2 s -1 under C. lanceolata plantations. The Q10 value was 1. 83 under M. laosensis plantations,which was significantly lower than 1. 99 under C. lanceolata plantations. The Rs rates exhibited distinct seasonal patterns under both M. laosensis plantations and C. lanceolata plantations and were dominantly controlled by the soil temperature,accounting for 77. 0%and 81. 6% of monthly variation,respectively. Linear regression analysis showed that Rs was significantly correlated with annual litter biomass,fine root biomass,soil organic carbon content,light fraction organic carbon content,microbial biomass carbon concentration and dissolved organic carbon concentration （ P〈0 . 05 ） . Stepwise regression analysis showed that litter biomass and microbial biomass carbon concentration were the most important affecting factors of Rs. Our results suggest that differences of Rs in different vegetation types may be attributed to the variations in the quantity and quality of litter input and the soil microbial biomass.