HulunBuir Sandy Grassland Blowouts( Ⅱ ): Process of Development and Landscape Evolution
呼伦贝尔沙质草原风蚀坑研究（Ⅱ）:发育过程

Development of sandy grassland blowout has mainly the following stages: Aeolian bare soil,crevasse in soil layer,actively developing blowout,fixed blowout,dieing out blowout.Fixed and dieing blowouts may re-active when environment condition worsens or human disturbance increases.Accordingly landform changes from typical grassland to desert-grassland,and sandland-grassland when blowouts are fixed by grassland vegetation but dunes remain active or to some degree fixed by shrubs or trees.The ultimate result of blowout is aeolian depression,which is somewhat easy to control,the coinstantaneous dunes are difficult to fix,and are highly dangerous for further development toward desert landscape.The development of blowouts and succession of vegetations change the typical flat,monotonous and dry grassland into undulating sand land-grassland with colorful vegetation of grass,shrubs and trees,and scattered blowout ponds.Efficient protection and rational utilization of sandy grassland in accordance with the practical situation along with its direction of evolution could maintain the natural ecosystem and even to facilitate it toward optimization,instead of the opposite.