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.