六盘山叠叠沟小流域华北落叶松人工林的冠层降水再分配特征

Characteristics of Rainfall Redistribution under the Canopy of Larix Principis-rupprechtii Forest in Diediegou watershed of Liupanshan Mountains

于2006-2007年生长季(5-10月)定位监测了六盘山北段叠叠沟小流域华北落叶松人工林的穿透雨、树干茎流和林冠截留特征,并基于同期气象数据初步分析了有关因素的影响。结果表明:林下穿透雨率存在明显的空间异质性,这种差异随着降雨量增大而变小。在整个测定期间,华北落叶松林穿透雨占总降雨量的(74.94±2.4)%,树干茎流占(0.16±0.03)%,而林冠截留占(25.08±2.41)%。穿透雨、树干茎流和林冠截留的数量与降雨量呈正相关(p<0.01),随着雨量或雨强的增加,穿透雨率升高,并且在高的雨量(>20 mm)和雨强(>5 mm/h)下逐渐趋于稳定。当降雨量到达6.44 mm时开始出现树干茎流。林冠截留率与降雨量、降雨历时和空气相对湿度呈显著负相关(p<0.05)。

Though a field investigation during growing season from May to October in 2006 and 2007 the partitioning of gross rainfall into throughfall, stemflow and canopy interception in the Larix principis-rupprechtii forest was studied in the small watershed of Diediegou located at the north part of Liupan Mountains, Ningxia. And the influence of meteorological factors was evaluated based on the simultaneous weather observation. An obviously spatial variation of throughfall ratio was observed, and this spatial variation declined with rising rainfall depth. The results also showed that throughfall, stemflow, and canopy interception accounted for （74.94±2.4）%, （0.16±0.03）%, and （25.08±2.41）% of the total rainfall, respectively. The amount of throughfall, stemflow and canopy interception was significantly （p〈0.01） and positively correlated with rainfall depth. As rainfall depth and intensity increased, the throughfall ratio in gross rainfall increased, but will gradually stabilized when the rainfall depth was higher than 20 mm and the rainfall intensity was higher than 5 mm/h. The stemflow began to appear when the rainfall depth arrived at 6.44 ram. The canopy interception ratio in gross rainfall decreased significantly （p〈0.05） and hyperbolically with increasing rainfall depth, rainfall duration, and air humidity.