热脉冲技术在确定胡杨幼树干液流中的应用

探讨了热脉冲技术在确定胡杨(Populus euphratica)幼树干液流中的应用.结果表明:在树木正常生长状态下,胡杨在4月下旬至5月中旬开花期树干单位面积液流通量为0.13～0.15L·cm^-2·d^-1;树干液流速度的动态变化呈多峰状曲线,6月份枝叶速生期树干单位面积液流通量为0.294L·cm^-2·d^-1;树干径向断面形成层以下不同深度的树液流速具有相同的日变化趋势;夜间,胡杨存在明显的树干液流上升现象,补充白天植物蒸腾丢失的大量水分,恢复植物体内的水分平衡;树干液流速度在不同的方位有所差异.并对胡杨单位面积液流通量与杨树、辽东栎、大叶白蜡、棘皮桦、五角槐、小美旱杨、油松进行了对比研究.

Application of Heat-pulse Technique to Determine the Stem Sap Flow of Populus euphratica

The heat-pulse technique was applied to study the stem sap flow of Populus euphratica in April and May of 2003. The results show that, in the natural conditions, the intensity of sap flow of Populus euphratica was 0.13～0.15 L·cm^-2·d^-1.The diurnal change of volume of sap flow showed a minor fluctuations.The velocity of sap flow of Populus euphratica at different depths below the cambium showed the same temporal change. At 12:00 it reached the maximum, and so did its difference . At night, the ascent of sap flow could be observed in the above main tree species owning to the existence of root pressure.The difference of sap flow rate at different direction could also be observedin stem section of P. euphratica. A comparison of thesap flux density of P. euphratica is made with that of Populus deltoids Bartr.cv.‘Lux’ex. -69/55, Pinus tabulae formis, Betula dahurica, Acer mono, Populus popular etc.