白桦人工林土壤各组分呼吸通量的变化特征

Variation Characteristics of Respiration Efflux of Soil Components in Betula platyphylla Plantation

运用Li-8150土壤CO2排放通量全自动测量系统,对东北林业大学哈尔滨实验林场白桦人工林土壤各组分呼吸通量的昼夜变化进行观测和研究,探讨各组分呼吸通量昼夜变化特征、月际变化特点和温度敏感性。结果表明:各组分呼吸通量均呈单峰昼夜变化特征;枯枝落叶呼吸通量昼夜内波动幅度远大于矿质土壤,尤其在春秋两季;根呼吸昼夜内波动幅度在5和10月份较大,其他月份较小;昼夜内各组分呼吸通量占土壤呼吸总通量的比例有波动,枯枝落叶和根呼吸通量的波动均表现出春秋两季较大、夏季较小的特点,矿质土壤则有相反的变化特点;各组分呼吸通量昼夜均值表现出显著的月际变化特点,与温度的月际变化正相关;各组分呼吸通量占土壤呼吸总通量的比例也呈现了显著的月际变化特征,枯枝落叶和根呼吸在春夏两季所占比例较高,秋季较低,而矿质土壤呼吸通量表现为春秋两季较高,夏季较低;各组分呼吸通量对地表下10 cm处的温度敏感性普遍高于对地表温度的敏感性;各组分呼吸通量对土壤温度的敏感性不同,表现为枯枝落叶>根>矿质土壤;Q10值的月际变化表现出低温较大高温较小的变化特点。

A Li-8150 CO2flux meter was used to measure respiration efflux of the soil components in a Betula platyphylla plantation located in the Harbin experimental forest station of Northeast Forestry University. The diurnal and monthly variation characteristics of respiration efflux,as well as temperature sensitivity of each component were investigated. Results showed that： the diurnal variation of respiration efflux for all components presented single peak values. The diurnal variation range of litter respiration flux was far greater than that of mineral respiration,especially in spring and autumn. Root respiration showed greater diurnal fluctuation range in May and October,but smaller fluctuations in the other months. The proportion of respiration for each component fluctuated diurnally. Litter and root respiration presented the identical feature,that is,the fluctuation was greater in spring and autumn but smaller in summer. The mineral respiration efflux presented the opposite feature. The mean diurnal respiration of each component varied monthly,and was positively correlated with the monthly temperature. The proportion of respiration efflux for all components also showed significant variations in different seasons. Litter and root respiration had higher proportion in spring and summer but lower proportion in autumn,and mineral respiration flux presented higher proportion in spring and autumn but lower proportion in summer. The respiration of all components was more sensitive to the temperature in 10 cm depth soil than that at soil surface. Each component had different temperature sensitivity,that is litter root mineral. The monthly change of Q10 was greater in low temperature and smaller in high temperature.