Ecohydrological change mechanism of a rainfed revegetation ecosystem at southeastern edge of Tengger desert,Northwest China

Study is made on a 45 km-long artificial ecosystem without irrigation in Tengger desert on the basis of long-term ecological monitoring and ecohydrological fundamentals.Changes in water allocation, utilization, cycle and balance patterns in more than 40-year evolution of the soil-plant system are analyzed. The formation of a drought horizon in shrub rhizosphere and its effect, ecohydrological function of the crust and its effect on the soil-plant system change are discussed. Driven by water self-regulation and water stress, the soil-plant system is going to develop towards the steppe desert to ensure more effective use and optimum collocation of water resource.     

流沙固定过程中土壤-植被系统演变

包兰铁路横穿腾格里沙漠沙坡头段,全长45 km,年降水量186 mm;流动沙丘相对高度20 m,以每年4 m的速度向东南方向移动。无灌溉条件下、工程措施与生物措施相结合的防沙固沙工程体系始建于1956年,近半个世纪以来该体系确保了包兰铁路畅通无阻。几十年的土壤植被系统演变正影响着整个防护体系。植被在从人工系统向自然系统的演变中经历了覆盖度从增加到减少的自疏过程、从灌木到半灌木到草本的变化;土壤从流动风沙土向钙积旱成土发育,地表生物结皮发育;降水在生态系统中的再分配过程已经彻底改变,新的水分平衡格局明显影响现有防沙固沙体系。