干旱区生态环境知识资源中心

A sandy grassland blowout consists of an aeolian depression formed in top soil and the underlying sand deposit underlie, and the adjoining redeposit of sand derived from the depression. Research based on field survey and topographic mapping combined with aerophotograph interpretation reveals that: (1) All the three sand land tracts in Hulunbuir Grasslands are composed of blowout depressions and adjoining dunes, with interlaying remnants of sandy grasslands as background; (2) blowout depressions and their adjoining dunes can be classified according to their morphometric characteristics, development stages, and initiating factors; (3) blowouts develop mostly in the upper parts of sidelong aweather and sunward slopes inclining southwestward when west wind prevails; (4) initiation of blowouts is closely related with the coupling of extreme droughts and wide spread intense human disturbance to the fragile topsoil layer. The investigations indicate that key factors to prevent desertification are to protect grassland vegetation and topsoil.