塔里木河上游典型绿洲土壤水盐空间分异特征

结合传统统计学与地统计学方法,以塔里木河上游典型绿洲阿拉尔垦区为研究区,根据64个样点的试验数据,分析样区表层(0-10cm)和亚表层(10-20cm)土壤水盐空间分异特征。结果表明,土壤水分、pH值、电导率和全盐具有明显的空间变异性。样区土壤盐碱化程度较高,土壤水分表现为中等变异性,pH值为弱变异性,电导率、全盐及大部分离子含量为强变异性,盐分呈现强烈的表聚性特性。土壤水分和表层pH值的半方差理论模型较符合指数模型,亚表层pH值、电导率和全盐较符合球状模型。各指标块金值/基台值在0.122～0.316之间,且表层小于亚表层,空间自相关性较高,变异更多受结构性因素影响,空间结构较为复杂。指标的空间分布与区域环境密切相关,各层土壤水分、电导率和全盐均为西北高于东南,即沿河岸-绿洲-荒漠方向递减,而pH值表现为相反的规律。研究区棉田的长期连作,使得水盐运动在多年耕作棉区较为活跃,中小尺度下水盐空间分布的异质性增强。

Spatial Variability of Soil Water-Salt in a Typical Oasis on the Upper Reaches of the Tarim River

Based on the data collected from 64 sampling sites,spatial variability of soil water-salt in the surface(0-10 cm) and subsurface(10-20 cm) layer of Aler reclamation area of the upper reaches of the Tarim river was analyzed by the methods of traditional statistics and geostatistics.The results showed that spatial heterogeneity of soil moisture,pH,conductivity and total salt were very obviously.The soil salinity and alkalization were generally high.The variation was moderate in soil moisture,weak in pH,and strong in conductivity and total salt.There was a trend of accumulation of salt to the surface.The semivariogram of soil water moisture and values of surface pH was best described by the exponential model while others by the spherical model.The ratio of nugget and still ranged from 0.122 to 0.316,which in surface layer was less than that in subsurface.The variables showed strong spatial autocorrelation resulting from effect of structural factors and spatial structures were complex.The spatial distribution of variables was closely related with the regional environment.The values of soil moisture,conductivity and total salt decreased gradually while the values of pH increased along the direction of riverside,oasis to desert.Continuous cropping is a factor that impacts on the spatial distribution and strengthens the spatial heterogeneity of soil water-salt.