干旱区绿洲-荒漠过渡带灌丛土壤属性研究

Soil properties under shrubs in arid area of oasis-desert transition belt.

以天山北坡绿洲-荒漠过渡带为研究区,选择3种类型的灌丛并采集不同位置和深度的灌丛土壤样品进行分析,研究灌丛土壤资源的聚集效应.结果表明,干旱区绿洲-荒漠过渡带不同类型灌丛对土壤粒度分布的影响不显著,土壤以砂和粉砂为主,红柳+裸地灌丛土壤粒度分布的聚集效应明显;灌丛土壤有机质、全氮和速效钾含量在冠幅下最高,其次为灌丛间低矮植物下,灌丛间裸地最低,呈现出明显的“肥岛”现象;不同灌丛类型和采样位置对土壤盐分离子和总盐含量的变化影响显著,且不同灌丛土壤资源的聚集效应各异;导致不同类型灌丛土壤资源富集率不同的原因有气候因素、灌木分布的土壤环境、灌丛高度和冠幅、灌丛间有无低矮植物等.

In arid and semi-arid areas with sparse vegetation cover, the spatial pattern of surface soil had a definite effect on soil salinity and nutrient flow, which is of highly importance for understanding the processes of land cover change. In this paper, a total of 3 shrub types and 2 soil sampling depths （0～20 and 20～40 cm） in the arid area of oasis-desert transition belt were selected to assess the spatial heterogeneity of soil rezources under shrubs. The results showed that different types of shrub had no significant effect on the particle size distribution of soil which was mainly composed of sand and silt, but significant cluster effect was observed under Tamarix ramosissima ＋ bare land shrub. Soils under shrub canopy had significantly higher contents of organic matter, total N and avail- able K, compared to those in open spaces, and presented obvious ＂fertile island＂ phenomenon. Shrub types had significant effects on soil salinity, and different duster effect existed in soils under different shrubs. The heterogeneity of soil resources resulted from a large number of factors, including climate, soil environment, height and extent of shrub canopy, stemflow, existance of other ground cover plants, and so on, many of which were mutually interactive.