HILL OF ENVIRONMENTAL EFFECT OF SAND CHARACTERISTICS ARE REVIEWED IN THIS PAPER

The classic method of sand land management does not treat the sand dune as a resource of environment,but tread it as the target of harness and bring it to the same level as around by means.Sand dune is the result of wind on drift sand.The formed sand dune is a windbreak;it decreases the intensity of wind and change the direction of wind.This leads to not only a decrease of erosion effect by wind,but also a decrease of the capacity of carrying sand by the wind.The drift sand falls down on the sand dune,and enlarges the sand dune,then increase the action of sand dune to stop the drift sand(positive feed back effect).So the sand dune is a windbreak made by wind,and a obstruction of drift sand made from drift sand.The sand dune is an important windbreak and sand-fixation resource of the sand land.The sand dune also can change microclimate of the sand land,and differentiate the heat quantity,temperature and the evapotransporation condition,form a condition for the biodiversity of vegetation.The dark slope of the sand dune is more moisture and lower temperature,and the sunny slope is higher temperature and drier than the zonal climate.This is the true reason why azonal vegetation forming in the sand land and some azonal plants distribute in the sand land.Investigation shows that the water for some trees is mainly from the soil of 2m layer,thus the dark slope of sand dune gives a more cool and moisture environment for the trees in the grassland region Therefore sand dune is an excellent environment resources on the sand land.