试论伏牛山南坡土壤垂直分异规律——兼论亚热带北界的划分

Laws of Soil Vertical Variations on Southern Slope of Funiu Mt.: Simultaneous Study on North Boundary of Subtropical Zone

在野外土壤调查和室内土壤理化分析的基础上,开展了伏牛山南坡土壤组成和性质垂直分异、土壤类型划分以及亚热带北界问题的讨论.研究表明:(1)调查断面上土壤表层HA/FA随高度增加而增大,且均小于1,海拔900 m左右土壤胡敏酸的芳构化程度最低;随高度增加土壤pH和盐基饱和度先下降后上升;海拔900 m以下的土壤中均有明显的黏化层,向上土壤黏粒淋溶淀积逐渐减弱;海拔900 m以下的土壤土体风化程度高,大部分氧化物的平均迁移系数和土体淋溶率小于1,土体Saf小于5.06,淀积层游离铁含量大于20 g·kg-1,铁游离度大于40%,具有弱富铁铝作用,剖面中出现明显的铁锰新生体,而向上土体风化程度减弱,不发生富铁铝作用,剖面中不出现铁锰新生体.(2)伏牛山南坡海拔550 m以下出现黏磐黄褐土(饱和黏磐湿润淋溶土),550～950 m出现普通黄棕壤(普通铁质湿润淋溶土),950～1900 m出现棕壤(普通简育湿润淋溶土或暗沃简育湿润雏形土),1900 m以上出现暗棕壤性土或草甸暗棕壤(暗沃冷凉湿润雏形土).(3)伏牛山南坡亚热带北界约在海拔950 m.

The vertical variations of soil compositions, properties, types according to genetic classification and taxonomic classification, and the north boundary of subtropical zone on the southern slope of Funiu Mountain were discussed in this paper based on soil survey in field and soil physical and chemical analysis in laboratory. There were some vertical varying laws of soil compositions and properties on the southern slope of Funiu Mountain. (1) The content of fulvic acid in soil humus exceeds that of humic acid in all profiles of soil (HA/FA<1). The ratios of HA/FA in surface horizons are rising from foot to top of the mountain. The degree of humification in soil humic acid at 900 m asl is the lowest. (2) Along the altitude from foot to top of the mountain, both soil pH and base saturation percentage go down first, then go up. (3) Soils below 900 m asl have remarkable clayification horizon, argic horizon appears in each soil profile, and soils above 900 m asl have no clayification and argic horizons. (4) All of soils have higher degree of weathering and ferrallitization, average migration coefficients (Kmx) of most oxides and the values of in all of soil bodies are below 1, the values of 'Saf' are smaller than 5.06, the contents of Fed in illuvial horizons are higher than 20 g·kg-1, the percentage of Fed/Fet in illuvial horizons is higher than 40%, and many kinds of ferromanganese (concretion and coating) appear in all soil bodies below 900 m asl. But for soils with lower degree of weathering, no ferrallitization takes place, and no ferromanganese appears in all soil bodies above 900 m asl. The north boundary of subtropical zone on south slope of Funiu Mountain is in the area between S3 and S4, ranging from 900 m to 1000 m, the average height of which is at 950 m above sea level.