分析了岷江上游河谷沿岸及九顶山西北坡表层土壤粒度、氧化铁、有机质、碳酸盐、p H、有机碳同位素、阳离子交换性、粘土矿物等理化性质。结果表明,三江至映秀段土壤具有较高的粘粉比、铁游离度及粘粒和有机质含量,而碳酸盐含量、p H和有机质δ13C值相对偏低,说明土壤发育较好、淋溶作用较强,反映了气候湿润和植被以乔木为主的环境特征;草坡至凤仪段土壤颗粒较粗、碳酸盐含量和p H较高,而铁游度和有机质含量较低,有机质δ13C值偏重,反映出干旱的气候和以C4植被为主的环境特征。九顶山西北坡土壤随海拔的增加粘粉比、有机质含量增大,出现纤铁矿而方解石缺失,反映干旱河谷区高海拔气候湿润;而海拔低于2 000 m的土壤粘粉比和粘粒、有机质含量较低,方解石含量和p H值较高,指示了干旱的气候特征。 The physical and chemical properties such as grain size, iron oxide, organic matter, carbonate, p H, organic carbon isotope, cation exchangeability and clay minerals in the upper reaches of Minjiang River and the northwestern slope of Jiuding Mountain were analyzed. The results showed that the soil from Sanjiang to Yingxiu had higher ratios of clay to powder, iron freeness and clay and organic matter content, but the carbonate content, p H and δ13C value of organic matter were relatively low, indicating that the soil was well developed and leached The effect is strong, which reflects the climatic humidities and the arbor-dominated environmental features of vegetation. The soil particles in Caoxi-Fengjian section are coarse, the carbonate content and p H are higher, and the content of iron amusement and organic matter is lower. The content of organic matter The δ13C values ​​are heavier, reflecting the arid climate and the environmental characteristics dominated by C4 vegetation. With the elevation increasing, the soil organic matter content increased, and the calcite disappeared, reflecting the humid climate of high altitude in the arid valleys. With the elevation of above 2000 m, Grain, organic matter content is low, calcite content and p H value is high, indicating arid climatic characteristics.