生长季红松树干液流密度的特征

Characters of Sap Flow Density for Korean Pine during Growing Season

利用热扩散探头测定系统监测不同径级红松样木生长季的树干液流,并初步分析和对比了不同样木液流密度的特征及变化趋势。晴天,红松树干液流日变化的表现可形成比较规则的单峰曲线;阴天,受温度、太阳辐射等环境因子的影响,红松树干液流则有较大的波动,并且液流密度的峰值相对较低;雨天,液流密度减到最低值。各径级样木液流密度的日变化比较一致,白天随着气温升高和植物蒸腾拉力的增大,液流密度增加,最大值一般出现在12:00左右,13:00以后持续降低,至凌晨左右减至最低,但为0的时候甚少,一般夜间都有液流存在,只是液流密度值较小。大径级样木液流密度平均值在6、7、8月份分别为6.01、3.12、2.54g·cm-2·h-1;中径级样木液流密度平均值在6、7、8月份分别为4.1、2.10、1.95g·cm-2·h-1;小径级样木液流密度平均值在6、7、8月份分别为1.89、1.13、0.90g·cm-2·h-1。大径级样木液流密度峰值在6、7、8月份分别为26.74、15.5、13.7g·cm-2·h-1;中径级样木液流密度峰值在6、7、8月份分别为17.51、10.12、11.58g·cm-2·h-1;小径级样木液流密度峰值在6、7、8月份分别为11.06、4.86、5.99g·cm-2·h-1。

Sap flow density （SFD） of Korean pine sample trees of different diameter classes was measured by thermal dissipation probe system during growing season, and its character and changing tendency were analyzed. Result showed that SFD presents a regular curve with a single peak under fine weather, while under cloudy weather SFD curve with a relatively low peak value has much fluctuations influenced by environmental factors such as temperature and solar radiation, and SFD decreases to the lowest value in rainy days. Daily changes of SFD for sample trees of different diameter classes are comparatively consistent： SFD increases with temperature and transpiration rising in the daytime, the maximum value occurs at noon, then continuously decreases from thirteen o＇ clock to midnight, and it reduces to the minimum value at wee hours. The SFD mean values of sample trees with larger diameter class in June, July and August are 6. 01, 3. 12 and 2.54 g ·cm^-2·h^-1 , respectively, those with middle diameter class are 4. 1,2.10 and 1.95 g ·cm^-2·h^-1 , and those with smaller diameter class are 1.89, 1.13 and 0. 90 g ·cm^-2·h^-1, respectively. The SFD peak values of sample trees with larger diameter class in June, July and Augnst are 26.74, 15.5 and 13.7 g ·cm^-2·h^-1, respectively, those with middle diameter class are 17.51, 10.12 and 11.58 g ·cm^-2·h^-1, and those with smaller diameter class are 11.06, 4. 86 and 5.99 g ·cm^-2·h^-1, respectively.