西双版纳望天树林林窗小气候特征研究

 对西双版纳望天树林林窗小气候要素的季节变化、水平差异进行了观测研究，并对比分析了两个大小不同林窗内温度垂直分布状况、相对湿度差别。结果表明：大林窗内温度、湿度、光照的日变化均比林内大；大林窗中央光照强度为林内的10倍以上，太阳总辐射量、净辐射量为林内的5倍以上，大林窗中央的蒸发耗热量大于林内，且均占各自净辐射的较大比例(70％～80％)，干季大林窗内温度、湿度日变化比雨季剧烈，大林窗内具有两个加热层(幼苗冠层、地表)，小林窗仅有一个加热层(幼树冠层)，且前者的加热强度大于后者，相对湿度日变化则是大林窗内较剧烈。

MICROCLIMATIC CHARACTERISTICS OF CANOPY GAPS IN SHOREA CHINENSIS FOREST IN XISHUANGBANNA

Seasonal and horizontal variation in microclimatic elements in closed forest and canopy gaps of two different sizes (200m2 and 140m2) were studied within a Shorea chinensis dominated tropical rainforest in Xishuangbanna. The following variables were measured: gross radiation, net radiation, light intensity, components of thermal balance, air relative humidity, vertical air temperature gradient, maximum and minimum air temperature, ground surface and leaf surface temperature. Variation of air, ground surface and leaf surface temperatures, air relative humidity and light intensity was greater in the large gap than in closed forest. Under dry season clear sky conditions both gross and net radiation in the center of the large gap were at least five times higher than in the closed forest ,and light intensity was at least ten times higher. Variation in air temperature and relative humidity in the large gap was also higher in the dry than in the rainy season. In the large gap center and in the closed forest about 70%～80% of the net radiation was used for evaporation. In the large gap there were two heating layers the seedling canopy and ground surface, while in the small gap only one heating layer was apparent the canopy of young trees. Heating intensity was also greater in the large gap. Diurnal variation in relative humidity was greater in the large gap than in the small gap.