泥石流频发区山地土壤环境因子与植被群落垂直梯度及其关系分析——以云南小江流域为例

Vertical gradient analysis of soil environmental factors and vegetation community in mountain areas of frequent debris flow: a case study in the Xiaojiang Watershed, Yunnan

海拔梯度和土壤环境是影响山地植被群落结构的关键因素,为揭示泥石流频发区植被群落的空间分布与演替规律,通过SPSS主成分分析、皮尔逊相关性分析和CANOCO5.0二维排序研究云南小江流域泥石流频发区山地生态系统土壤环境因子和植被群落的垂直梯度分异及其相互关系.结果表明:在海拔梯度上,土壤的垂直地带性分异规律与纬度地带性分异规律类似,从高到低依次为温带地带性土壤、北亚热带地带性土壤和亚热带地带性土壤;草本植被大致可以划分为鹅绒委陵菜(Potentilla anserina)–扭黄茅(Heteropogon contortus)群落、醡浆草(Oxalis corniculata)–牛尾蒿(Artemisia dubia)群落和苞茅(Hyparrhenia bracteata)群落3类;因该区地质灾害及人为干扰严重,生态环境恶化,原生乔木群落已极少分布,现以华山松、云南松人工林为高山主要植被类型,松柏混交林为亚高山主要植被类型,桉树、新银合欢人工林为低山主要植被类型.从典范对应分析(CCA)排序结果来看,不同植被群落与土壤环境因子之间的关系存在明显分异.综上,海拔梯度、土壤有机质、土壤全磷和重金属(铜、锰)含量是影响泥石流频发区植被群落格局的主要因素.

Vertical gradient and soil environment are the key factors affecting mountain vegetation community structure. However little is known about the relationship between vegetation community and soil environmental factors. This paper aimed to determine the spatial distribution of vegetation community in typical area with high-frequency debris flow. SPSS principle component analysis, Pearson correlation analysis and CANOCO5.0 Two-dimensional ordination method were applied to determine the vertical gradient differentiation of the soil environmental factors and vegetation community as well as the relationship between them. The vertical zonal soil distribution rules were similar to latitude zonal distribution rules. The order from high to low was Temperate zonal soil, North subtropical zonal soil and Subtropical soil. The shrub-grassland community could be divided into three types, namely Potentilla anserina- Heteropogon contortus community, Oxalis corniculata-Artemisia dubia community and Hyparrhenia bracteata community. In the seriously degraded ecological environment caused by geological disasters and human disturbances, native arbor community was scarcely distributed. The main vegetation types of alpine zone were artificial forests composed of Pinus yunnanensis and Pinus armandii; those of subalpine zone were mixed forests of pine and cypress; and those of lower mountain belt were artificial forests composed of Eucalyptus robusta and Leucaena leucocephala. Canonical correspondence analysis suggested a significant relationship between vegetation and soil environmental factors. The results suggested that the main factors affecting the vegetation distribution in the typical area with high frequency debris flow are elevation gradient, soil organic matter, soil total phosphorus and heavy metals.