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运用经典统计方法,以桂西北喀斯特峰丛洼地4个植被演替阶段(草地、灌木林、次生林、原生林)土壤表层(0～15 cm)和剖面为研究对象,采用冗余分析(RDA)方法分析土壤物理性质的时空分异成因.结果表明:灌木林和原生林表土的粘粒(<0.002 mm)和粉粒(0.002～0.05 mm)含量分别与其他3个演替阶段有显著差异;草地与次生林之间各粒级颗粒含量差异不显著;各演替阶段土壤砂粒(0.05～2.0 mm)含量均无显著差异;草地的容重与其他3个演替阶段差异极显著.草地粘粒含量随坡位升高而增加,其他植被类型为中坡位粘粒含量最高,且同一植被类型下不同坡位之间差异不显著.原生林0～30 cm土壤各层次间的粘粒含量变化幅度(14.55%)大于草地(7.12%)、灌木林(11.24%)和次生林(13.77%),人类干扰对表层土壤颗粒组成有很大影响.土壤物理性质主要受土壤有机碳和各演替阶段植被类型的影响,其中砂粒含量受裸岩率的影响较大.
By using the classical statistics method, the surface (0 ~ 15 cm) and profile of the four vegetation succession stages (grassland, shrub forest, secondary forest and primary forest) in the karst peak depression of the northwestern Guangxi were studied. Method was used to analyze the spatiotemporal differentiation of soil physical properties.The results showed that the contents of clay (<0.002 mm) and silt (0.002-0.05 mm) in the topsoil of shrub and primary forest were significantly different from those of the other three successional stages, respectively. There was no significant difference in the contents of grain fractions between the grassland and the secondary forest. There was no significant difference in the contents of soil sand (0.05-2.0 mm) between the succession stages of grassland and secondary forest. The grass weight was significantly different from that of the other three successional stages. With the increase of slope position, the other types of vegetation have the highest content of clay in mid-slope and no significant difference between different slope positions under the same vegetation type.Changes of clay content in different layers of 0-30 cm soil in primary forest (14.55%) was greater than that of grassland (7.12%), shrub forest (11.24%) and secondary forest (13.77%). Human disturbance had a great influence on the composition of soil surface soil. The soil physical properties were mainly affected by soil organic carbon Type of impact where grit The content is greatly affected by the rate of bare rock.