毛乌素沙地东南缘不同沙漠化阶段土壤-植被关系研究

Study on the correlation of soil-vegetation in different desertification stages on the southeastern edge of Mu Us Sandy Land

【目的】揭示沙漠化过程中土壤、植被的相互作用规律,为土壤-植被系统的修复提供科学依据。【方法】选择毛乌素沙地东南缘陕西榆林地区沙质草原地带沙漠化程度明显的区域为研究区,在野外调查和图像资料的基础上,采用空间序列方法,将沙漠化过程分为非沙漠化阶段（植被盖度〉35%）、潜在沙漠化阶段（植被盖度25%～35%）、轻度沙漠化阶段（植被盖度15%～25%）、中度沙漠化阶段（植被盖度5%～15%）、重度沙漠化阶段（植被盖度〈5%）5个阶段,在每个阶段随机选取3个1 m×1 m的样方,采集样方内植物和不同土层土壤样品,研究沙漠化过程中植被特征（物种密度、物种丰富度、多样性指数、地上生物量、有机质含量、全氮含量、植物C/N）和土壤理化性质（土壤颗粒、含水率、容重、pH、有机质含量、全氮含量、土壤C/N）的变化,并对土壤与植被的相互关系进行分析。【结果】沙漠化过程中,植被、土壤特征均呈现规律性变化,且在不同的土层范围内植被特征与土壤理化性质之间均存在较强的内在相关性;物种密度、物种丰富度、多样性指数、地上生物量与土壤粘粒、含水率、容重、pH和土壤C/N之间相关系数的最大值多出现在0～10 cm土层;而土壤有机质、全氮等养分含量对植被的影响主要发生在10～30 cm的土层;土壤、植被之间的关系在一定程度上可以定量化。【结论】土壤-植被的物理表征特征之间的相互作用主要发生在土壤表层,营养元素之间的相互作用则发生在土壤下层,说明土壤-植被系统的恢复过程应是先自上而下由植被改善土壤,之后自下而上由土壤养育植被的过程。

【Objective】 The study uncovered the laws of the interactions between soil and vegetation in order to,provide scientific foundation for the recovery of the soil-vegetation system.【Method】 Choosing the distinct desertification region on the southeastern edge of Mu Us Sand Land in Yulin area as the study area,based on the field survey and map data,by methodology of ＂Temporal for Spatial＂,we divided desertification into non-desertification stages（vegetation cover 35%）,potential desertification stages（vegetation cover 25%-35%）,mild desertification stages（vegetation cover 15%-25%）,moderate desertification stages（vegetation cover 5%-15%）,severe desertification stages（vegetation cover 5%）,and in each stage we selected three 1 m × 1 m quadrats randomly,collected the samples of plants and soil in different layers,studied the changing of the vegetation characteristics（species density,species richness,diversity index,aboveground biomass,organic matter content,total nitrogen content and vegetation C/N） and soil physical and chemical properties（soil particles,moisture content,bulk density,pH,organic matter content,total nitrogen content and soil C/N） in the process of desertification,and analyzed the relationship between soil and vegetation.【Result】 The relationships between the characteristics of vegetation and the physical and chemical properties of soil in the process of desertification on the southeastern edge of Mu Su Sandy Land were researched.The results showed：the characteristics of soil and vegetation were changing regularly during the process of desertification,and there existed significant correlation between the characteristics of vegetation and the physical and chemical properties of soil;the maximum correlation coefficients between vegetation species density,species richness,diversity index,aboveground biomass and soil clay particle,soil moisture content,soil bulk density and pH existed in a depth between 0 to 10 centimeters;and the influence of soil organic matter,total nitrogen content on the vegetation mainly occurred in the lower depth between 10 to 30 centimeters.【Conclusion】 The interactions between the physical features of soil and vegetation always occurred in the surface soil,while the interactions between nutrients always occurred in the lower soil.So,we consider that the recovery process of the soil-vegetation system should be first up-down by the vegetation improving the soil,then down-up by the soil fostering vegetation.