陕北毛乌素沙地生物结皮发育特征的初步研究

通过野外采样和室内分析相结合,掌握了陕北毛乌素沙地不同采样点生物结皮层的理化性质以及该地区生物结皮的发育特征,为以后进一步研究毛乌素沙地生物结皮的防风固沙效应奠定了理论基础.结果表明:随着生物结皮的发育,结皮层厚度增加.最大值为11.82 mm;土壤颗粒细化,0.02～0.05 mm之间的颗粒含量为7.3%～27.7%,高于流沙中的颗粒含量;由于颗粒的细化,结皮层容重增加,其抗剪强度明显提高,且抗剪强度与厚度和容重之间存在一定的相关性.生物结皮层pH值为7.23～7.81,低于流动沙地的pH值;有机质、N和K含量明显高于流沙的含量;P含量有所增加但不明显.研究表明,各个样点的生物结皮效应表现有所不同,原因有多方面.主要是结皮的发育程度、植被盖度以及采样点地形地貌之间的差异所引起.

Primary Study on Development Characteristics of Biological Soil Crust in MU Us Sandy Land in Northern Shaanxi

By sampling in fields in Mu Us sandy land in northern Shaanxi and analysis in laboratory,physical and chemical properties and development characteristics of biological soil crust in different sampling points were mastered.This lays a foundation for the further research on soil crust'S effects of windbreak and sand fixation.The result indicted that:With the development of biological soil crust,its thickness growed to 11.82 mm;Soil particles in biological soil crust refined,contents of particles whose diameter ranges from 0.02-0.05mm are 7.3%-27.7%,higher than in sand;Because of the refinement,bulk density of biological soil crust rises and shear strength increases apperantly.pH in biological soil crust is from 7.23 to 7.81,lower than in sand:The contents of organic matter,N and K are higher in crust than in sand apperantly,but the content of P increase a little.In this research there are differences among all physical and chemical properties of biological soil crust in different sampling points.Reasons of the differences are mainly the degree of crust's development,vegetation coverage and topography and geomorphology in different sampling points.