哀牢山亚热带常绿阔叶林林区太阳辐射特征

Characteristics of Solar Radiation of Subtropical Broad-leaved Forest Area in Ailao Mountains,Southwest China

利用中国科学院西双版纳热带植物园哀牢山森林生态系统研究站林外自动气象站2005-02到2007-12的辐射观测数据,对哀牢山北部山顶亚热带常绿阔叶林林区的太阳辐射平衡各分量的年、季节和日变化特征进行了分析,得出哀牢山林区太阳辐射年总辐射为5146.4MJ/(m2·a),干季的太阳总辐射量(2764.7MJ/m2)占全年总量的53.7%,雨季的太阳总辐射量(2381.7MJ/m2)占全年总量的46.3%.各辐射分量年值占总辐射年值的百分率为净辐射41.3%,反射辐射21.0%,有效辐射37.7%。太阳辐射各分量占太阳总辐射的比率在不同的季节由于天气状况和大气中含水量的不同存在一定的差异,反射辐射和有效辐射的分配率均是干季大于雨季,净辐射的分配率则是雨季大于干季.从全年来看,净辐射分配率的变幅最大(31.1%～51.9%),有效辐射次之(28.6%～48.6%),反射辐射最小(18.4%～24.2%);从分配率的日变化可知,反射辐射和有效辐射均是清晨和傍晚较高,昼间较小,净辐射则相反,各辐射分量分配率在昼间的变化均较小。不同季节各辐射分量占总辐射的比重不同,干季有效辐射所占比重最大,其次是净辐射,反射辐射最小;雨季净辐射所占比例最大,其次是有效辐射,反射辐射最小。与相近纬度的鼎湖山和鹤山林区相比,哀牢山林区总辐射量高于两地,而年均气温(热量)低于两地,由此可以认为哀牢山林区在较低的气温条件下能分布大面积的中山湿性常绿阔叶林,且生长繁茂、发育良好,较强的太阳辐射应是其重要原因之一。

Based on the observation data of solar radiation in Ailao mountains forest ecosystem research station from Febmary 2005 to December 2007, temporal variations of solar radiation balance were analyzed. The results show that total annual global radiation is 5 146.4 MJ/（m^2·a）. The global radiation in the dry season （2 764. 7 MJ/m^2） accounted for 53.7% of total annual global radiation and in the rainy season （2 381.7 MJ/m^2） accounted for 46. 3% of it, with 41.3%, 21.0% and 37.7% of global radiation partitioned into net radiation, reflective radiation and effective radiation respectively. Because of the seasonal differences of the weather conditions and water content in atmosphere, the distributing ratio of solar radiation components is different. In the dry season the distributing ratio of reflective radiation and effective radiation is higher than that in the rainy season respectively, while the net radiation distributing ratio shows the contrary behavior. On the whole year, the variational range of distributing ratio of net radiation（31.1%～51.9% ） is the highest, effective radiation （28.6% ～ 48.6% ）is lower and the reflective radiation （ 18.4% ～ 24.2% ） is the lowest; on the daily variation, the distributing ratio of reflective radiation and effective radiation is higher in the early morning and dusk, lower in the daytimes, but the distributing ratio of net radiation is higher in the daytime, lower in the early morning and dusk. In different seasons, the distributing ratio of solar radiation components is different： effective radiation 〉 net radiation 〉 reflective radiation in the dry season and net radiation 〉 effective radiation 〉 reflective radiation in rainy season. Compared with Dinghushan and Heshan forest area located in the similar latitude, although Ailao Mountains has lower mean annual air temperature （quantity of heat）, it has stronger solar radiation. Therefore it suggests that strong solar radiation maybe the important reason for wide distribution and good development of evergreen broad-leaved forest in Ailao Mountains.