小良试验站三种生态系统能量平衡的研究

A STUDY ON ENERGY BALANCE IN THREE ECOSYSTEMS AT XIAOLIANG EXPERIMENTAL STATION

1981年－1990年对混交林、按树林、裸地三种生态系统进行了连续观测，对其能量平衡问题进行了对比研究。结果表明对太阳辐射的反射率以混交林的最小，桉树林次之，裸地的最大；裸地的净辐射值是桉树林和混交林第二作用层的1．57倍，这反映出林冠对太阳辐射进入林内的阻碍；混交林、桉树林和裸地的蒸散耗热分别占净辐射的95％，59％和70％；土壤导热率在不同的林分和不同的季节中有所变化，但其变化的规律不明显；土壤的热量通量在年内的平衡状况以裸地最好，年内就已基本平衡，混交林内的热量通量年内差额最大。整个混交林系统的热量平衡支出项主要为蒸散，小气候以温暖湿润为基本特征，按树林和裸地的热量平衡支出项主要靠乱流交换，常常以高温干旱的小气候为主。

Based on consecutive measurement from 1981 - 1990 at Xiaoliang ExperimentalStation in Guangdong, the energy balance in three ecosystems, mixed forest, eucalyptus forest and bare land, was studied comparatively. The reflection rate to solar radiation wasin the order bare land＞eucalyptus forest ＞mixed forest. The net radiation (NR) on bareland was 1.57 times of that on mixed forest and eucalyptus forest. The energy dissipationby evapotranspiration was 95% of NR for mixed forest, 59% of NR for eucalyptus forestand 70% of NR for bare land. The heat conductivity of soil changed a little in differentecosystems and various seasons, but the regularity was not apparent. Annual heat flowthrough soil was nearly balanced for bare land, which differed from that for mixed forestand eucalyptus forest. As a whole, the heat environment was best in mixed forest andworst in eucalyptus forest, which was shown by that the output of energy from the mixedforest was mainly through evapotranspiration and that from the eucalyptus forest wasmainly through air movement. This is why the micro-climate in mixed forest is warm andwet but that in eucalyptus forest is hot and dry.