六盘山华山松(Pinus armandii)林降雨再分配及其空间变异特征

利用2004和2005年生长季(6～9月份)六盘山自然保护区的香水河小流域内华山松天然林的穿透降雨、树干径流和冠层截留量观测资料,通过对华山松林降雨再分配特征和穿透降雨空间变异及其影响因素的综合分析,所得结果表明华山松天然林的穿透降雨量、树干径流量和冠层截留量,分别占大气降雨量的84.34%、0.72%和14.94%.穿透降雨在林内具有较大的空间变异,其变异程度随降雨量的增加而减小,冠层对穿透降雨具有一定的聚集效应,降雨量越高时效应越明显; 华山松冠层结构特征是影响穿透降雨的重要因素, 叶面积指数、冠层覆盖度、冠层厚度及距树干的距离等都会影响穿透降雨的空间分布,其中以叶面积指数的影响最大.由分析结果可知,冠层结构特征是决定大气降雨再分配和空间变异的重要生态因素之一.

Rainfall redistribution and its spatial variation in the stand of Pinus armandii in the Liupan Mountains, China

During the growing-season (Jun.-Sep.) of 2004 and 2005, the throughfall, stemflow and canopy interception of a natural forest stand of Pinus armandii in Liupan Mountains Nature Reserve of northwestern China were observed. The rainfall distribution, the spatial variability of throughfall and their influencing factors were systematically analyzed. The result indicated that the throughfall, stemflow and canopy interception accounts for 84.34%, 0.72% and 14.94% of the rainfall in open field, respectively. The spatial variability of throughfall within this stand was estimated for different rainfall events. The coefficient of variance of throughfall decreases with increasing rainfall depth. It was found that the canopy has a congregation effect on the throughfall in a certain extend, and this effect increases evidently with increasing rainfall depth. The canopy structure characteristics, such as leaf area index (LAI), canopy density, canopy thickness, and the distance of sampling sites to the stem of sample tree, are very important factors influencing the spatial distribution of throughfall. Of these factors, the influence of LAI is the highest one. It was concluded that the canopy structure is one of the most important ecological factors that affect the rainfall redistribution and spatial variability within forest stand.