西伯利亚落叶松树干液流的动态变化

Dynamic changes of sap flow in the trunk of Larix sibirica Ledeb.

基于热扩散原理,利用TDP茎流计连续测定6—9月西伯利亚落叶松的树液流动速率,分析其季节变化和日变化特征。结果表明：（1）西伯利亚落叶松树干液流的最大速率出现在7月,且其南向树干液流值为是其北向液流值的1.08倍;但二者的变化趋势相同,但变化速率和变化幅度有差异。（2）树干液流的日变化呈＂昼高夜低＂的多峰型变化规律,12：00—17：00时段的液流处于高水平状态,5：00—8：00夜间液流的为0,夜间补水完成。（3）南向树干液流启动时间较北向的早0.5h,日最大液流速率是北向树干的1.16倍。（4）树干液流速率与气温和太阳辐射呈极显著正相关（P〈0.01）,与相对湿度和土壤温度呈极显著负相关（P〈0.01）,与风速呈显著正相关（P〉0.05）,各因子的影响力排序为：气温〉空气相对湿度〉光合有效辐射〉土壤温度（10~20cm）〉土壤温度（0~10cm）〉风速。

In order to know the water cycling in forest ecosystem,the sap flow of Larix sibirica Ledeb.was monitored using TDP（thermal dissipation method）consistently in the Kanas National Nature Reserve from June to September.The results showed that：（1）The maximum sap flow happened in July.Dynamic changes of sap flow in the south trunk of L.sibirica were similar to its north trunk,and the sap flow value of the south trunk was 1.08 times as great as that of the north trunk.（2）The diurnal variations of sap flow in the south trunk and north trunk were both the multi-peak type.The sap flow was higher in period of time from 12∶00to 17∶00,but reached lowest from 5∶00to 8∶00.（3）The starting time of sap flow in the south trunk was 0.5hearlier than that of the north trunk,and the maximum value of sap flow in the south trunk during a day was 1.16 times as great as that of the north trunk.（4）The sap flow had positively very significant relationship with air temperature and PAR（P〈0.01）,negatively very significant relationship with relative humidity and soil temperature（P〈0.01）,and positively significant relationship with wind speed（P〉0.05）.The influence order of sig-nificant factors was air temperaturerelatively humidityPARsoil temperature（10—20cm）soil temperature（5—10cm）〉wind speed.