哀牢山亚热带常绿阔叶林与林外草地太阳辐射比较

Variation patterns of solar radiation above subtropical evergreen broadleaved forest and open area in Ailao Mountains

太阳辐射是森林生态系统的主要能量来源,为探讨亚热带常绿阔叶林对太阳辐射的影响,本研究利用哀牢山亚热带森林生态系统研究站太阳辐射观测数据,对林外草地、林冠上的太阳辐射平衡各分量的年、季节变化特征进行了分析。结果表明:森林辐射的季节变化因随植被的变化而与林外草地辐射有所差异。森林有效辐射占总辐射的比率、反射率均低于林外草地,导致净辐射占总辐射比率高于后者。与我国各地的辐射分配率相比,哀牢山亚热带常绿阔叶林的净辐射占总辐射比率较高,反射率较低。总辐射与相近纬度同植被类型的鼎湖山、鹤山相比,分别高207.7和357.5 MJ.m-2,这对生长在海拔2200 m以上、温凉潮湿环境下的亚热带常绿阔叶林来说,显得异常重要。

Solar radiation is the primary source of energy for forest ecosystem.To explore the influence of subtropical evergreen forest on the distribution of solar radiation,a comparative study was made on the variation patterns of solar radiation above the forest canopy and open area in Ailao Mountains,based on the observation data of solar radiation from the Subtropical Forest Ecosystem Station in Ailao Mountains.There existed differences in the annual variation of solar radiation above the forest canopy and open area due to the seasonal variation of vegetation.The ratio of effective radiation to global radiation and the albedo above the canopy was lower than that above the open area,but the ratio of net radiation to global radiation was in adverse,due to the influence of the canopy.Compared with those in other areas of China,the ratio of net radiation to global radiation above the forest canopy in Ailao Mountains was higher,while the albedo was lower.The glboal radiation in the Mountains was averagely 207.7 MJ·m^-2 and 357.5 MJ·m^-2 higher than that in the Dinghu Mountains and Heshan Mountains with the similar altitude and vegetation type as Ailao Mountains,respectively,suggesting that high global radiation looked very important for the subtropical evergreen forests at the altitude above 2200 m and under temperate cool moist condition.