高黎贡山土壤腐殖质特性与团聚体数量特征研究

PROPERTIES OF HUMUS AND CONTENT OF SOIL AGGREGATES IN SOILS ON GAOLIGONG MOUNTAIN

采用野外调查与室内分析结合的方法,研究高黎贡山土壤腐殖质特性与团聚体数量特征,对进一步了解高黎贡山生态系统中土壤特征,降低土壤侵蚀,减少水土流失提供科学依据。结果表明:土壤腐殖质的组成具有明显地带性特征,有机质、腐殖酸含量、胡/富(HA/FA)随海拔高度的降低呈先上升后下降的趋势,A1层胡敏酸(HA)、富里酸(FA)含量分布规律为暗棕壤>棕壤>棕色针叶林土>亚高山草甸土>黄棕壤>黄壤>黄红壤。A2层腐殖酸、FA变化趋势为暗棕壤>棕壤>棕色针叶林土>黄棕壤>黄壤>亚高山草甸土>黄红壤。A1层HA、FA分子复杂程度、化学稳定性比A2层强。1～0.5mm和<0.25mm粒径的团聚体含量占绝大多数,约占60%～70%。随着海拔高度的降低,粗粒减少,细粒增多。土壤团聚体服从对数正态分布,其几何平均直径与几何标准差、土壤可蚀性K值之间存在负相关关系,土壤可蚀性K值与几何标准差存在正相关关系,同时土壤也具有一定的分形特性。其中亚高山草甸土几何平均直径(Dg)、平均重量直径(MWD)值最大,几何标准差(δg)、可蚀性K值、分形维数(CFD)值最小,土壤结构稳定性和抗蚀能力相对较强。胡敏酸含量是影响土壤可蚀性的重要因素。

Properties of humus and contents of aggregates in the soils on the Gaoligong Mountains were studied in the lab and through field survey as well to gain a better knowledge about characteristics of the soils in the Gaoligong Eco-system and provide a scientific basis for soil erosion control. Results show that composition of the soil humus therein demonstrated apparent zonality, and its contents of organic matter, humic acid, HA/FA increased first and then decreased with declining elevation. Humic acid and fulvic acid in Al layer followed a decreasing order of dark brown 〉 brown 〉 brown coniferous forest soil 〉 sub-alpine meadow soil 〉 yellow brown 〉 yellow 〉 yellow red soil in content, while those in A2 layer did one of dark brown 〉 brown 〉 brown coniferous forest soil 〉 yellow brown 〉 yellow 〉 sub-alpine meadow soil 〉 yellow red soil. The HA and FA in A1 horizon was higher than those in A2 horizon in molecular complexity and chemical stability. Soil aggregates, 1 - 0.5mm and 〈 0.25mm in particle size, occupied an overwhelming majority, accounting for about 60%- 70% of the soil, and decreased in particle size with declining elevation, displaying a pattern of lognormal distribution. Negative correlations were observed of their geometric mean diameter with geometric standard deviation and soil erodibility K-factor, while a positive correlation was between geometric standard deviation and soil erodibility K-factor. Moreover, the soil also demonstrated some fractal features. Subalpine meadow soil was the highest among the soils in Dg and MWD but the lowest in δg, soil erodibility K-factor and CFD, and its soil structure stability and resistance to erosion was relatively stronger. The content of humic acid is believed to be an important factor, influencing soil stability.