大沙鼠在柽柳沙包“肥岛”形成过程中的作用

Role of Rhombomys opimus in the development of “fertile island” in tamarisk mounds in Junggar Basin

灌木"肥岛"的形成和维持是物理和生物过程共同作用的结果。植物是影响灌木"肥岛"形成的关键因素;动物活动亦能影响土壤的理化性质,促进"肥岛"的形成。本文以中亚干旱区的代表性物种"柽柳"和"大沙鼠"为研究对象,研究了大沙鼠活动对柽柳沙包"肥岛"效应的影响。结果表明:无大沙鼠定居的柽柳沙包具有"肥岛"效应,但土壤养分含量并无显著提高;大沙鼠定居后,柽柳沙包出现明显的"肥岛"效应,土壤养分含量显著高于丘间对照地;大沙鼠活动促进了15～50cm深层土壤养分的富集,速效氮含量甚至是相同深度无洞柽柳沙包的2倍以上。表明大沙鼠活动促进了柽柳沙包"肥岛"的形成。

Shrub ＂fertile island＂ is created and maintained by a combination of physically and biologically mediated processes.Plants are the key factor affecting the formation of ＂fertile island＂,while the activities of burrowing animals can affect the soil physical and chemical properties,which promotes the development of the ＂fertile island＂.In this paper,tamarisk（Tamarix spp.）,a dominant shrub species growing in oasis-desert ecotone,and great gerbil（Rhombomys opimus）,a widely distributed rodent in Central Asia,were taken as study objects to investigate the ＂fertile island＂ effect of R.opimus in tamarisk mounds in Junggar Basin.In the tamarisk mounds without the settlement of R.opimus,＂fertile island＂ effect existed,but the soil nutrients contents had no significant increase.After the settlement of R.opimus,the tamarisk mounds showed obvious ＂fertile island＂ effect,with significantly higher soil nutrients contents than the inter-mound areas.The burrowing activities of R.opimus promoted the enrichment of nutrients in 15-50 cm soil layer,and the content of soil available nitrogen in the tamarisk mounds with R.opimus burrows was over 2 times higher than that in the mounds without R.opimus burrows at the same depths.Our study indicated that the burrowing activities of R.opimus promoted the development of ＂fertile island＂ in the tamarisk mounds.