陕北水蚀风蚀交错区两种生物结皮对土壤饱和导水率的影响

该文以陕北水蚀风蚀交错区普遍发育的地表和地上两种生物结皮为研究对象，分别以3种非生物结皮（无结皮、物理结皮、去除生物结皮）为对照，使用盘式入渗仪测定其饱和导水率。结果表明：与无结皮土壤相比，两种类型生物结皮均可极显著降低土壤饱和导水率；与去除生物结皮土壤相比，两种类型生物结皮对土壤饱和导水率的降低均不显著；与有物理结皮发育的土壤相比，地表生物结皮对土壤饱和导水率的降低不显著，而地上生物结皮对土壤饱和导水率的降低显著。一方面，两种生物结皮对土壤饱和导水率均有明显降低作用，预示生物结皮在降雨活动中可能会增加径流、降低入渗，阻碍研究区水分亏缺条件下的植被恢复和生态与环境建设。另一方面，与不同的对照相比，生物结皮对土壤饱和导水率的影响截然不同，该结论可在一定程度上解释当前有关生物结皮影响土壤水分入渗方面所存在的分歧。

Effects of biological soil crust on saturated hydraulic conductivity in water-wind erosion crisscross region, North of Shaanxi Province, China

Biological soil crust(BSC) develops extensively in water-wind erosion crisscross region on the Loess Plateau, northern Shaanxi Province of China. There are two types of BSC developing above soil surface(hypermorphs) and at soil surface(perimorphs) respectively in the region. The soil saturated hydraulic conductivity K_s of BSC and three types of control(no any crust, physical crust and removed BSC) were measured by tension infiltrometer to explore the effects of BSC on soil water infiltration and conductivity. The results show that, both two types of BSC decrease K_s remarkably compared with no crust, and the K_s between BSC and removed BSC has no significant differences. But compared with physical crust, the decrease of K_s by perimorphs is insignificant and hypermorphs is significant. It is indicated that both two types of BSC may hinder vegetation recovery and eco-environmental construction by increasing runoff and decreasing infiltration in rainfall. It is also included that the effects of BSC on soil saturated hydraulic conductivity are different compared with the different controls, which will explain the contradiction of results reported in past few years about the BSC's effects on soil water infiltration at some extent.