莽山土壤发生学属性的垂直分异与系统分类

Altitudinal Differentiation in Soil Genetic Attribute and Taxonomy in the Mangshan Mountain.

  • 摘要:
    目的 弄清亚热带地区花岗岩中山土壤发生学属性与土壤类型的垂直地带性分布规律。
    方法 选取莽山不同海拔带的8个典型单个土体,野外观测土壤剖面形态,室内测定土壤理化性质,划分土壤类型,在地理发生分类、中国土壤系统分类和国际土壤系统分类之间进行参比。
    结果 土体厚度介于18 ~ 180 cm,以山体中部最为浅薄。质地主要为砂质壤土和砂质黏壤土,黏粒含量随海拔升高而降低;山体上部(> 1000 m)土壤B层有腐殖质、黏粒胶膜和黏粒累积形成的黏化层。土壤有机碳和CEC值随海拔升高而升高,但腐殖质层浅薄,多为淡薄表层。这些土壤指标呈垂直地带性,反映了花岗岩中山土壤发生学特性。供试剖面土壤呈酸性,铝饱和度和铁游离度较高,铁质特性与铝质现象普遍,CEC为9.7 ~ 29.1 cmol (+) kg−1,一些土壤发生学属性指标(土壤色调、pH、铁游离度、铝饱和度)无明显垂直地带性。中国土壤系统分类划分出富铁土、淋溶土、雏形土和新成土4个土纲、5个亚纲、6个土类、8个亚类、8个土族和8个土系。
    结论 土纲垂直带谱为雏形土、富铁土(400 ~ 700 m)—雏形土、新成土(700 ~ 1200 m)—雏形土、淋溶土(1200 ~ 1800 m),呈组合、跨带地域分布规律。与土壤地理发生分类相比,土壤系统分类侧重体现更多土壤发生学属性指标,同一海拔带内划分出了更多土壤类型,反映土壤多样性。

     

    Abstract:
    Objective This study aims to understand the altitudinal zonal differentiation of soil genetic attribute and soil type in subtropical granite mid-mountain landscapes.
    Method Eight typical pedons at different elevations of Mangshan Mt. were selected. The soil profile morphological characteristics were described in the field, the soil physiochemical properties were measured in the laboratory, and the soil types were defined and cross-referred among the Chinese Soil Genetic Classification, the Chinese Soil Taxonomy, and international soil taxonomy systems.
    Result The soil thickness varied from 18 -180 cm, with the shallowest in the half way up to the summit. The soil texture was mainly sandy loam and sandy clay loam. The clay content decreased, whereas the soil organic C and CEC contents increased with increasing elevation. The soil B horizons developed on the middle-upper part of the mountain (> 1000 m) had argic horizon characterized by humus-clay films and clay accumulation. The humus horizons were shallow and mainly were ochric epipedons. These soil indices changed with altitude reflecting the genetic characteristics of soils derived from granite mid-mountain. The soils were acidic, relatively high levels of Al saturation and free Fe, commonly ferric property and alic evidence, and CEC ranged from 9.7 - 29.1 cmol ( + ) kg−1. These soil indices (matrix color, pH, Free Fe, Al saturation) did not vary markedly with increasing elevation. Soils were classified to 4 soil orders (ferrosols, argosols, cambosols, and primosols), 5 suborders, 6 soil groups, 8 subgroups, 8 families, and 8 series according to the Chinese Soil Taxonomy.
    Conclusion The altitudinal belt of soil order was cambosols and ferrosols (400 - 700 m), cambosols and primosols (700 - 1200 m), and cambosols and argosols (1200 - 1800 m), showing the spatial distribution pattern of soil associations and cross-zone. Comparing to the soil genetic classification, soil taxonomy reflects additional soil genetic attributes and divides diverse soil types within the same altitude zone.

     

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