西双版纳不同季节热带次生林林窗光照时空分布特征

A Study on the Sun shine Spatial and Temporal Characteristics in the Tropical Secondary Forest Canopy gap in the Different Season in Xishuangbanna

利用西双版纳不同季节 (1、4、7、1 0月 )次生林林窗 8方位光照观测资料 ,探讨了林窗光照的时空变化特征及变化规律。结果表明 :在西双版纳由于区域性天气现象 (雾 )、太阳高度和林窗边缘树木的共同影响 ,形成不同季节、时间林窗区域光照强度在时空上的明显差异即高值时空位移现象及空间不对称性。林窗光照高值区域不是出现在林窗中央而是林窗某一侧 ,并且在不同季节、不同时间光照高值区域会出现动态推移的现象。光强分布势使林窗区域热力产生不同的作用 ,进而导致林窗区域热量传输和热量储存的差异 。

Light intensity measurements on 8 azimuth at the secondary forest canopy gap were conducted in Xishuangbanna, Yunnan, in Jan. Apr. Jul. and Oct. 1999.On the basis of this measurement, spatial and temporal variations of light intensity in the secondary forest canopy gap were discussed. The results indicated that: because of the influence of condition of foggy environment and sun altitude and the tree, spatial and temporal variations of light intensity on the forest gap are significant in different time in different season, that is the phenomena about peak value displacing and spatial asymmetry, and the source of maximum values of light intensity do not present to the center, but to the other side, and that it displays shifting along with time. Temporal diversity and spatial Asymmetry is the characteristic of distribution of light intensity, it makes thermodynamic regime different on different sites, and results in differences on caloric transmitting and caloric storing in the gap, finally the different thermodynamic effect is generated.