黑河中游绿洲区不同土地利用类型表层土壤水分空间变异的尺度效应

Scale-dependency of spatial variability of surface soil moisture under different land use types in Heihe Oasis,China.

了解表层土壤水分空间变异及其尺度效应,可获取土壤水分真实变异,并可为客观揭示土壤水分空间变异制定合理采样方案提供参考.用"再采样"方法对黑河中游张掖绿洲区林地和农地表层土壤水分空间变异的尺度性进行研究.结果表明:研究区林地和农地表层土壤水分变异程度随土壤水分含量的增加而增加;变异系数随采样尺度的增大而更接近真实变异值.在干旱和湿润条件下,当采样幅度在一定范围内增大时,林地和农地土壤水分的变异系数、MoranⅠ指数、块金值、基台值及林地变程均不断变大,而农地在干旱条件下的变程无固定变化规律.当采样密度在一定范围内增大时,块金值、变程不断增大,但变异系数、MoranⅠ指数、基台值均不受影响.

To study the surface soil moisture spatial variability and its scale effect is of significance to understand the real variability of soil moisture and to objectively provide a reference for construc- ting a logical sampling scheme. By using ＂re-sampling＂ method, this paper studied the scale-de- pendency of the spatial variability of soil surface moisture in the woodland and farmland in the oasis ecological system in the middle reaches of Heihe River. The results showed that the variation degree of the surface soil moisture in the test woodland and farmland increased with increasing soil moisture content, and the coefficient of variation （CV） became closer to the true value when the sampling scale increased. Under both dry and moist conditions, and when the sampling amplitude increased within a definite range, the CV, Moran＇ s I index, nugget, and sill of soil moisture in the woodland and farmland as well as the variation range in the woodland all increased, while the variation range in the farmland under arid condition did not show a stable regular pattern. When the sampling den- sity increased within a definite range, the nugget and variation range increased, but the CV, Mo- ran＇ s I index, and sill showed less change.