HulunBuir Sandy Grassland Blowouts: Influence of Human Activities
呼伦贝尔沙质草原风蚀坑研究（Ⅳ）:人类活动的影响

The shapes,development stages,and formation causes of 187 modern blowouts in HulunBuir Sandy Grassland were compared on the background of different grazing and human activity pressures.It was discovered that 87% of blowouts are caused by human activities,with plowing,grassland motor vehicle natural road,and resident related activities counting for 35.8%,34.8%,and 16% respectively.Blowouts caused by resident related activities have the widest spread.And 97% of the plowing-caused bare soil and blowouts are in active development,indicating destruction to soil layer structure and material loss brought forth by plowing is serious and has long aftereffect.Herding can bring fixed blowouts back to active along their edges and at dunes,as well as to facilitate blowouts' process of level off and revegetation.What is important is to set herding pressure or quota in a reasonable scale.With regard to morphological change of blowouts in relation to causes,large scale destruction of top soil layer by plowing results in wide spread bare soil and large round blowouts,whereas motor vehicle natural roads results in string lined elongated blowouts when the ruts mill and cut through top soil layer.HulunBuir Grassland is endangered by a new phase of sandy desertification.Protection of grassland vegetation and top soil layer is vital to avoiding the development of blowouts.Facilitate the resumption of soil layer formation and revegetation is the fundamental way to control blowouts.