流沙固定过程中土壤-植被系统演变对水环境的影响

横穿腾格里沙漠的防风固沙体系始建于 1 95 6年 ,确保了包兰铁路近半个世纪的畅通无阻。在几十年的土壤 -植被系统演变中 ,花棒 柠条 油蒿 -干旱砂质新成土的人工系统演变为油蒿 雾冰藜 小画眉草 -简育正常干旱土的半天然、天然系统 ;生物结皮发育、结皮层形成改变了降水的再分配过程 ;在 2 0～ 5 0 0cm深度的干旱层因灌木的排水作用而形成 ,低等植物也开始与草本和灌木竞争水分 ,深根系的灌木很难得到降水的补给 ,逐渐退出了防护体系 ;土壤 -植被系统趋于更薄的活动层。水环境的这些变化正影响着整个防护体系的结构和功能

IMPACT OF EVOLUTION OF PLANT-SOIL SYSTEM ON THE WATER ENVIRONMENT DURING THE MOBILE DUNES STABILIZATION

The system of wind defense and sand dune stabilizat ion, which crossed the Tengger desert and was began to construct in 1956, has insured the Baotou-Lanzhou railway straightway for almost half century.During succession of soil-plant system for decades, a artificial system of Hedysarum scoparium + Caragana korshinskii + Artemisia Ordosica-Ari-Sandic Entisols has developed into a semi-natural and natural system of Artemisia Ordosica+ Bassia dasyphylla + Eragrostis poaeoides-Hap-Orthic Aridisols.Development of biocrust and crust horizon changed redistribution of precipitation.A drought horizon formed in 20~500 cm depth because of shrub transpiration.Low plants began to compete water with grasses and shrubs.Shrubs with deep roots obtained hardly rainfall supply and dropped out protection system gradually.Soil-plant system went to a thinner active horizon.All of the changes were affecting the structure and function of the whole protection system.