森林土壤具有良好的水文生态功能，其结构特征影响土壤的水分物理性质。研究了长江上游地区的贡嘎山东坡亚高山不同林型下土壤的结构特征，并采用平均结构直径和结构分形特征进行评价，同时还研究了土壤渗透性、持水性等水分特征。研究结果表明：成熟阶段的混交林地土壤结构性最好，具有较强的水文生态功能；采伐迹地最差；其他林地类型介于其间。在该地区生态环境受到较好的保护，成熟混交林和过熟林占80％以上，因此总林上说该区的土壤结构状况和水分效应也较好，但由于该区生态环境脆弱，仍需加强管护。

Forest soil has great hydro ecological function and its structural property affects soils water physical properties. Structural properties and its mean weight diameter(MWD)and fractal dimension(FD)for evaluation, infiltration and water holding of soils from different forests on east slope of Gongga mountain, which lies in the upper reach of Yangtse River, were studied. The results were as follow: structure and water effect of soils under mixed mature forests were good, soils after plant clear cutting were bad, others are between them. In this region, the eco environment was well protected and mixed mature & over mature forests were over 80%. Though the soil structure and water effect in this region were good as a whole, some protect measures are needed.