表层覆盐对新疆巴里坤盐湖土壤呼吸特征的影响

Effect of Salt Covering on Soil Respiration in Balikun Saline Lake,Xinjiang,China

本文以新疆巴里坤盐湖周边硫酸钠型盐渍土壤为研究对象,通过土柱异位培养的方法,使用开路式土壤碳通量测量系统Li-8100,研究了不同覆盐量(CK、1倍覆盐、2倍覆盐、3倍覆盐和4倍覆盐处理)对土壤呼吸特征的影响。结果表明:(1)土壤呼吸日变化呈单峰曲线,其峰值表现出随覆盐量增加而增加的趋势;4倍覆盐处理下土壤呼吸速率的峰值出现时间(15:00)比其他处理(17:00)有所提前;凌晨0:00—6:00,部分土壤呼吸速率呈现负值。(2)覆盐后土壤CO_2日排放量随时间呈先增加后降低的趋势,与气温变化一致;培养期间土壤CO2日均排放量表现出随覆盐量增加而增加的趋势,4倍覆盐处理下土壤CO_2日均排放量显著高于CK处理(P<0.05)。(3)土壤温度敏感系数Q_(10)表现出随覆盐量增加而增加的趋势。综上可见,覆盐处理显著影响了盐湖周边盐渍化土壤CO_2排放通量、特征和土壤温度敏感性,因此,在研究气候变暖对盐渍化土壤呼吸影响时,不仅要考虑增温对土壤呼吸的直接影响,也要考虑土壤盐层厚度与土壤温度敏感性的变化。

Using soil column incubation method, the effect of salt covering （CK, no salt covering; T1; T2; T3 and T4： salt covering with 1, 2, 3 and 4 times amount of salt in soil） on soil respiration was studied with a Li-8100 automated soil CO2 flux system in Balikun Saline Lake. The diurnal variation of soil respiration showed a single peak curve, with the peak value increased with amount of covered salt. The time of peak value showed in 15：00 under T4 treatment, but 17：00 under other treatments. The flux of soil respiration was negative from 0：00 to 6：00. Soil respiration showed a trend that first increase then decrease with incubation time after salt covering. Change of daily average soil respiration rate during incubation time and Q10 value showed an increase trend with amount of covered salt, with daily average soil respiration rate under T4 treatment significantly higher than that under CK treatment. Our study suggested that not only temperature, but also salt covering and its influence on Q10 value should be considered when study saline soil respiration under climate warming condition.