陕北水蚀风蚀交错区两种生物结皮对土壤理化性质的影响

以黄土高原陕北水蚀风蚀交错区六道沟小流域为例,研究了该区以苔藓为主要成分的沙土和黄土两种生物结皮对土壤理化性质的影响。结果显示:(1)两种生物结皮均能显著增加土壤饱和含水量和田间持水量,降低容重和饱和导水率,其中沙土生物结皮还可明显粘化0～25cm土壤质地;(2)两种生物结皮均能不同程度的增加土壤全量养分、速效养分以及有机质含量,降低pH值,但其影响多数集中在表层或结皮层;(3)土壤化学性质中,全氮、速效磷和有机质受生物结皮影响程度较大,而全氮、速效钾和有机质受生物结皮影响土层较深;(4)沙土生物结皮对土壤理化性质的影响程度大于黄土生物结皮。两种类型生物结皮对所研究土壤理化性质的影响总体有利于该区生态环境的改善,且沙土生物结皮较黄土生物结皮具有更为重要的生态功能。

Effects of biological soil crust on soil physicochemical properties in water-wind erosion crisscross region, northern Shaanxi Province, China

Biological soil crust(BSC) develops extensively in water-wind erosion crisscross region of the Loess Plateau,northern Shaanxi Province of China.We compared the effects of two types of BSC on soil physicochemical properties in Liudaogou watershed in the region.The two types of BSC,one developing on sand soil and another on loess soil,are moss dominated with main species of Bryum arcticum(R.Brown) B.S.G.and Barbula vinealis Brid.The results show that:(1) Both types of BSC increase saturated soil water content and field capacity,decrease bulk density and saturated hydraulic conductivity.BSC on sand soil can increase soil clay content in 0-25 cm layers;(2) Both types of BSC increase total N,total P,available N,available P,available K and organic matter,and decrease pH value,although most of these effects are observed in surface soil only;(3) Compared with other soil chemical properties,BSC have greater effects on soil total N,available P and organic matter,and deeper effects on total N,available K and organic matter in soil profile;(4) BSC on sand soil have greater effects on soil physicochemical properties than BSC on loess soil.As a whole,both types of BSC are beneficial for ecological construction in the research region,although the ecological function of BSC developing on sand soil maybe more important than BSC on loess soil.