内蒙古东部两大沙地土壤理化特性沙漠化演变规律的比较

Comparison on Soil Physicochemical Properties in Desertification Process between Two Sand Lands in East of Inner Mongolia

为了了解不同地带沙地土壤理化特性沙漠化演变规律的差异及其机制,研究比较了科尔沁沙地和呼伦贝尔沙地土壤理化特性的沙漠化演变特征,得到以下结论:沙漠化过程中,2个沙地的土壤黏粉粒含量均大幅度下降,沙粒含量明显增加,但科尔沁沙地土壤机械组成的变化幅度要大于呼伦贝尔沙地,而且前者黏粉粒主要释放期早于后者;科尔沁沙地土壤温度趋于下降,呼伦贝尔沙地土壤温度的变化趋势不明显,但土壤含水量均略有增加;土壤有机碳、氮、磷含量、碳/氮均显著下降,其中科尔沁沙地下降幅度大于呼伦贝尔沙地;表层土壤pH值均显著下降,下层土壤pH值值变化不显著;导致两沙地土壤理化特性变化存在差异的主要原因是其背景土壤质地和土壤粗化速率不同。

A field investigation on soil chemical and physical properties in different kinds of desertified grassland was conducted during July,2009 simultaneously in Hulunbeir and Horqin sand lands with same longitude and different Latitude to understand the differences and mechanisms on changes of soil chemical and physical properties in desertification processes in sandy grassland of different regions.The results showed that ①with desertification developing,soil clay and silt contents decreased and sand content increased significantly in the two sand lands,but changing range on soil texture was greater in the Horqin Sand Land than that in the Hulunbeir Sand Land,and primary emission period of clay and silt was easier in the former than the later.②Soil temperature and water content were higher in the Horqin Sand Land than that in Hulunbeir Sand Land.With desertification development,soil temperature decreased in Horqin Sand Land and changing trend of soil temperature was not obvious in Hulunbeir Sand Land,but soil water contents increased slightly in both the two sand lands.③With desertification development,soil organic carbon,nitrogen,phosphorus contents and C/N decreased significantly and the declined range was greater in topsoil than that in subsoil.The declined range of soil organic carbon,total N,total P and available N were greater in the Horqin Sand Land than that in Hulunbeir Sand Land,but available P was the exact opposite.④With desertification development,soil pH decreased significantly in the topsoil and changes of soil pH was not significantly in the subsoil in both of the two sand lands.⑤ Primary reasons to cause the differences in changes of soil physicochemical properties resulted from differences of background soil texture and speed of soil coarseness between the two sand lands,and changes in soil organic carbon and total nutrient contents also were subject to changes in soil temperature in the Horqin Sand Land.