基于土壤粒度分析的草原风蚀特征探讨

A Probe into Grassland Wind Erosion based on the Analysis of Soil Particle Size

对放牧、开垦和围封下内蒙古典型草原地表覆盖状况、土壤粒度与有机碳含量进行测定,分析人类活动对草原风蚀的影响。结果表明,与围封草地相比,过度放牧草地的群落盖度及高度分别降低了44.23%和80.71%,根系生物量下降了37.83%。由于植被覆盖及根系密度的降低,过度放牧草地土壤表现出明显的风蚀特征,表层土壤粗粒化明显,表层土壤平均粒径比围封草地增加了约1倍。而开垦造成的风蚀程度则更为严重,开垦使表层土壤颗粒平均粒径增加2.5倍。因此,过牧与开垦下的典型草原已形成为一个重要的沙尘源。土壤颗粒粗化直接引起土壤有机碳含量的下降,土壤中小于0.1mm颗粒组分每被吹蚀1%,其有机碳含量将减少0.2546g·kg-1。

The land surface vegetation coverage,soil particle size and organic carbon content in the typical steppe under overgrazing,cultivation and exclosure were investigated in Inner Mongolia and the influences of human activity on grassland soil erosion was analyzed.The results were as follows.Compared to enclosed grassland,the vegetation coverage,height and root biomass of overgrazing grassland decreased by 44.23%,80.71%and 37.83%respectively.Due to the decline of vegetation coverage and root density,the soil of overgrazing grassland demonstrated a significant wind erosion.Overgrazing resulted in the increase of sand content in the surface soil and about 100%increase of the mean soil particle size.Furthermore,cultivation had led to serious soil wind erosion and 2.5 times increase in mean particle size.The overgrazed and cultivated grassland had become an important source of sand dust.The coarsening of soil particle directly aroused the decline of soil organic carbon content,and when 1 percent of soil particle content below0.1 mm was blown away by wind,organic carbon content in soil reduced 0.2546 g·kg-1.