摘要
由于碳酸盐岩岩性的不同,发育的喀斯特在生态环境因子的组合和质量上有较大的差异,形成了不同的石漠化类型。在大量典型样地调查的基础上,以岩性、小生境种数、小生境组合、裸露石面面积、石砾含量和土壤总量6个因子为指标,通过聚类分析和主成分分析相结合的方法,将喀斯特石漠化分为2大类型,即显性石漠化和隐性石漠化,分析比较了它们的主要特征。同时,分别石漠化类型选择了程度评价指标,用坐标综合评定法和欧氏距离公式建立了石漠化数量评价模型,即石漠化程度指数模型,用石漠化程度指数对样地的石漠化现状进行了评价,将6 4个样地划分为未石漠化,轻度、中度、强度和极强度5个等级。
Karst rocky desertification is a special process and phenomenon that transforms a karst area into rocky landscape resulted from almost devoid of soils and vegetation. Different carbonate rocks have different types of weathering, soil pedogenesis and characteristics of hydrology, which leads to making different karst terrains and rocky desertification. Degrees of karst rocky desertification vary differently with changes in the types of disturbance, their intensity, timing, and magnitude. Due to a lack of understanding of the types and degrees of development of rocky desertification, research into its prevention, and the restoration of affected land, has been restricted to a considerable extent. In this study, data on lithology, surface micro-habitats, soil, vegetation, litter, gravel content, and above-ground biomass were collected from sixty-four 10m × 10m subjectively chosen sample plots (representing different types of rocky desertification) located in the center and south of Guizhou Province, China. The data were used to classify and quantify rocky desertification based on properties and characteristics of the land sampled. Based on results of factor analyses, 6 factors out of 14 were selected as basic factors for classification. These were: lithology; numbers of micro-site types, micro-site combinations, area of bare rock, gravel content, and bulk of soil. Both cluster analysis and principal component analysis were also performed but gave similar classification results. Research on land properties and calculated results showed that land affected by rocky desertification could be classified into two types, termed as apparent and recessive types. Apparent rocky desertification developed in the areas where lithology was pure limestone, dolomitic limestone, or limy dolomite, with more than three micro-site categories, rock-ditch, high rate (%) of outcrop, and a variety of micro-sites. Recessive rocky desertification developed on dolomite lithology where there was little or no outcrop generally displayed better continuity of soil coverage, but is characterized of simple micro-site and higher gravel content. Through the quantitative assessment of the factors affecting rocky desertification, five factors (i.e. community biomass, community height, depth of weathered layer, soil depth, and coverage of over- and under-storey) were selected as quantitative assessment variables for classifying the intensities of rocky desertification; while the factors of the area of outcrop and gravel contents as assessment variables for classifying the two types of rocky desertification. This makes it into two assessment systems with six factors in each. Rocky Desertification Index (RDI) model was established by the coordinated-based integrating estimation and the Euclidean distance. The RDI expresses the degree to which land is degraded by rocky desertification. A higher RDI value indicates a higher degree of degradation. The values of RDI were divided into 5 classes using an optimal partitioning method. The range of RDI values represented by each class was: Class 0=0 to 0.20; Class 1=0.21-0.40; Class 2=0.41 to 0.60; Class 3=0.61 to 0.84; Class 4=0.85 to 1.00, indicating non-degraded, lightly degraded, moderately degraded, strongly degraded, and extremely degraded, respectively, by rocky desertification.
出处
《生态学报》
CAS
CSCD
北大核心
2005年第5期1057-1063,共7页
Acta Ecologica Sinica
基金
贵州省省长人才基金资助项目 (2 0 0 3 -0 4-12 )
贵州大学人才基金资助项目~~
关键词
贵州
喀斯特石漠化
数量评价
Guizhou
Karst rocky desertification
quantitative assessment
