不同植被覆盖度沙垄土壤化学性质的空间分异

Spatial Variation of Soil Chemical Properties of Longitudinal Dunes with Different Vegetation Coverage Levels

为了研究温带固定半固定沙漠土壤化学性质与地表植被的关系,本文以古尔班通古特沙漠西南缘莫索湾地区沙漠-绿洲过渡带为研究区,分别选取植被覆盖度为10%和15%的半固定沙垄及植被覆盖度为30%的固定沙垄。采集了各沙垄不同地貌部位的土壤样品,室内测试了土壤pH、电导率、有机质、全氮和全磷等指标。结果表明:①随着植被覆盖度下降,沙垄西坡、坡顶和东坡,土壤pH、电导率、有机质、全氮和全磷呈逐渐降低趋势;②不同地貌部位的分布格局各沙垄表现不一致,沙垄A和沙垄B的pH、电导率、有机质、全氮和全磷含量最大值均出现在垄间地,其他部位之间没有明显的规律,沙垄C的pH和电导率最大值出现在垄间地,而土壤养分含量在坡顶部位富集;③各沙垄不同土层土壤性质分布规律相对一致,土壤pH、电导率随着土层深度的增加呈上升的趋势,而土壤养分随着土层深度的增加而降低;④土壤化学性质空间分布异质性与植被的分布格局密切相关,相互影响,当植被覆盖度较高时,生物作用起主导作用,当植被覆盖度较低时,风蚀、地形等非生物因素作用加强,影响生物作用,植被对土壤颗粒和养分的拦截及富集作用逐渐减弱或消失。

The fixed dunes with 30% vegetation coverage and the semi-fixed dunes with 10% and 15% vegetation coverage were selected as the typical plots in the Mosuowan oasis-desert ecotone in the southwestern marginal zone of the Gurbantunggut Desert. The purpose of the study was to reveal the relationship between soil chemical properties and vegetation in the temperate fixed and semi-fixed desert. Soil samples were collected from different parts of dunes to test soil pH value,electrical conductivity,organic matter content,total nitrogen content and total phosphorus content in laboratory. The results showed that: ① With the decrease of vegetation coverage,the soil pH value,electrical conductivity,organic matter content,total nitrogen content and total phosphorus content were decreased gradually on the western and eastern slopes as well as the top of the longitudinal dune;② Distribution patterns at different parts of different longitudinal dunes were different. The maximum pH value,electrical conductivity,organic matter content,total nitrogen content and total phosphorus content of both the longitudinal dune A and B occurred in the inter-dune land,but there was no obvious regularity in other parts. The maximum pH value and electrical conductivity of the longitudinal dune C occurred in the inter-dune land,while the maximum soil nutrient content occurred on the dune top;③ The distribution trend of soil properties in different layers of dune was relatively consistent. The soil pH value and electrical conductivity were increased with the increase of soil depth,while the soil nutrient content was decreased with that;④ The spatial distribution heterogeneity of soil chemical properties was closely related to the distribution pattern of vegetation,and they interacted each other. When the vegetation coverage was high,the biological effect played a dominant role;when the vegetation coverage was low,the abiotic factors,such as wind erosion and topography,played an important role in enhancing the biological effects,and vegetation intercepted and enriched the soil particles and nutrients.