沙坡头地区生物结皮的水文物理特点及其环境意义

The Characteristics of Biological Crust and Its Environmental Significance in Shapotou Region

包兰铁路中甘段,大规模生物防护体系取得了明显的生态环境效益。随着时间的展延环境诸要素发生变化,特别生物结皮的形成和发育,制约着生态防护体系的演变和发展。生物结皮是人工生态防护体系建立后,外来尘埃动态沉积,一年生植被的侵入,植物凋落物腐解,在微生物及其环境条件综合作用下的新生成物。生物结皮作为一新的环境因子介入人工生态防护体系之中,使沙面固结稳定,增强了抗风蚀的能力。同时它的形成和发育,增大了降水的无效蒸发,使降雨入渗浅,沙地水分恶化,导致深根性植物衰退,浅根性的半灌木和草本植物得到发展,使人工体系向半人工半自然体系变化和演变。

The large-scale biologic protective system along Zhongwei-Gantang section of Baotou-Lanzhou railway have achieved substantial eco-environmental benefit. However, as time went on, the environmental condition had been changed, especially the formation of biologic crust exerted an influence on the development of the protective system.Biologic crust is a complex outcome under the actions of dynamically deposited dust, annual vegetation invasion, rotten fallings of plant, micoorganism and other elements after the artificial ecologic protective system has been established.Biologic crust as a new environmental factor entered into the atificial protective ecosystem and strengthened the ability of wind-erosion resistance as well as sand surface stability. On the other hand, the development of biolgic crust increased the ineffective evaporation of rainfall, decreased the infiltration depth of precipitation, deteriorated moisture ondition of sandy land, and led to the degeneration of deep-root plants and finally caused the succession of artificial protective system.