苏北不同杨树人工林经营模式下土壤呼吸日变化观测与测定方法比较

采用动态密闭气室法(IRGA)对苏北地区具有代表性的4种杨树人工林经营模式和农田对照的土壤呼吸进行了日动态观测,同时采用碱液吸收法(AA)测定土壤日呼吸速率,并把两种方法测定的结果进行了比较。结果表明:①采用动态密闭气室法(IRGA)和碱液吸收法(AA)测定土壤日呼吸速率范围分别为3 065~5 880 mgCO2-C/(m2.d)和1 060~1 697 mgCO2-C/(m2.d)。AA法测定结果均低于IRGA法,平均为IRGA法测定结果的33.8%,两者测定结果的线性相关性达到显著水平,线性关系为IRGA=3.8231A-A1118。②P1和P2模式下杨树根系呼吸分别占土壤总呼吸量的47.9%和13.5%。③土壤呼吸日变化为单峰型曲线,峰值出现在13:00~17:00,与温度变化有很好的一致性。

Diurnal Dynamic Patterns of Soil Respiration for Poplar Plantations and its Different Measuring Methods

The dynamic closed-chamber IRGA method was used to determine the diurnal(24 h) dynamic pattern of soil respiration,and daily soil respiration rates calculated with this method were compared to those measured with the static alkali absorption(AA) method for four poplar plantation(Populus×euramericana cv.)patterns and agriculture system in the northern area of Jiangsu province.The results were as follows:①Daily soil respiration rates measured with IRGA and AA methods were 3 065～5 880 mg CO2-C/(m2·d) and 1 060～1 697 mgCO2-C/(m2·d) respectively.The result measured with IRGA method was significantly higher than that measured with AA method,with AA method averaging 33.8% of that measured with IRGA method.Linear relationship between results measured with AA method and IRGA method was significant and the regression equation was IRGA=3.823 1AA-1118.②Root respiration accounted for 47.9% and 13.5% of total soil respiration in P1 and P2 patterns,respectively.③Diurnal fluctuations in soil respiration rate showed a single-peaked curve and highest soil respiration rate occurred at 13:00～17:00.The dynamics of soil respiration rate was well consistent to that of soil temperature.