[目的]为了分析和检验塔克拉玛干沙漠边缘绿洲-荒漠中灌木“肥岛”效应对荒漠土壤肥力的作用强度.[方法]采用野外取样和室内实验分析相结合的方法,测定了胡杨(Populos euphraticu)灌丛林及周边过渡带中不同深度土壤养分含量;通过计算富集率和构建土壤肥力指数模型评价南疆绿洲-荒漠过渡带的土壤肥力水平.[结果]过渡带和灌丛下的土壤pH均呈碱性,且随土壤深度增加碱性增强;土壤中全N、全P、全K和速效N、速效P、速效K含量都随着土壤深度的增加而降低.富集率表明,在胡杨灌丛,土壤OM、全N、全P、全K、和速效养分含量都表现为EB ＞1,且EB在垂直剖面上呈现先增大后减小的趋势,在20 ～ 40cm深度土壤聚集效果最为显著,其中有机质、全K、速效N、速效K富集率相对较大.SFI模型标明,绿洲-荒漠过渡带灌丛下的土壤肥力状况明显高于灌丛间过渡带.[结论]胡杨灌丛下存在典型的灌丛“肥岛”现象,灌木的长期生长能够增强土壤空间异质性的作用,改善灌丛下土壤养分结构和肥力水平,使土壤沙化程度得以缓解.%[Objective] IThe study aims to analyze and test the effect of shrub ‘ fat island’ on desert soil fertility in the oasis desert in the edge of Taklimakan Desert.[Method] The method combining field sampling and laboratory analysis was adopted,The soil nutrient contents in different depths of Populus euphratica shrub forest and its transition zone were measured,The soil fertility level of oasis-desert ecotone in South Xinjiang was evaluated by calculating enrichment rate and constructing soil fertility index model.[Result] The soil pH in the ecotone and shrub were alkaline,which increased with soil depth;The contents of total N,total P,total K and available N,available P,available K in soil decreased with the increase of soil depth.The enrichment rate showed that the contents of OM,total N,total P,total K and available nutrient in soil were EB ＞ 1 in Populus euphratica shrub,and EB increased first and then decreased in vertical section,At 20-40 cm depth,soil accumulation was most significant,in which organic matter,total K,available N and available K enrichment were relatively large.The SFI model shows that the soil fertility under shrub was obviously higher than that in the oasis-desert ecotone.[Conclusion]There was a typical shrub ‘ fertile island’ phenomenon under the Populus euphratica shrub,long-term growth of shrubs can enhance the spatial heterogeneity of soil,and improve the nutrient structure and fertility level of soil under the shrubs,The soil desertification can be alleviated.
展开▼
