区域尺度地形因素对奇台绿洲土壤盐渍化空间分布的影响

Impacts of Regional Topographic Factors on Spatial Distribution of Soil Salinization in Qitai Oasis

在对土壤盐分实测分析的基础上,研究新疆天山北坡奇台绿洲盐碱土的分布特征同SRTM数据提取的地形信息的相关性,探讨了区域尺度基于地形因子的土壤盐碱化分异规律.结果表明:研究区土壤盐化与碱化并存,主要盐分类型为硫酸钠盐和氯化钠盐.盐分在垂直剖面上呈V型分布,硫酸盐具有明显的表聚性.在区域尺度上,地形对当前盐碱土分布的空间格局起主要作用,低于680 m高程的缓坡区为积盐区,高于740 m高程的陡坡区为碱化区.研究区的碱化是典型的脱盐碱化,盐化和碱化的演化趋势表现为明显的逆向特征,即盐分随着海拔高度的降低而增高,pH则随着海拔高度的降低而减少.地形因素对表层(0～20 cm)和中层(>20～60 cm)土壤盐分分布格局影响较大,随着深度的增加,相关性下降.高程与大部分盐分指标呈极显著相关,其对盐渍化程度、各盐分离子空间分布格局的影响作用大于坡度.

Based on monitoring data of soil salt content in the Qitai Oasis in the Northern Slope Area of Tianshan Mountain in Xinjiang,the correlation between the distribution characteristics of saline-alkali soil and topographic information extracted from SRTM data was investigated,and the spatial variation and distribution based on regional topographic factors was discussed.The results showed that salinization and alkalinization of the soil occurred simultaneously in the study area where the vitriol soil and the chloride saline soil were the main soil types.The soil salt content presented a V-shaped distribution pattern of depth profile,and the surface-gathering characteristics of the vitriol salt were very obvious.At a regional scale,topography played an important role in the spatial distribution of the saline-alkali soil,with salt accumulating within the slightly sloped area below the elevation of 680 m.Alkalinization occurred in the steeply sloped area above 740 m.Alkaline-earth in the area presented a typical desalination-alkalinization feature,and the evolvement of salination had a reversed pattern to that of alkalinization.With decreased altitude,soil salt content increased and pH dropped concurrently.Topographic factors had a major effect on the salt distribution patterns within the 0-20 cm and 20-60 cm soil layers（surface layer and subsurface layer）;the deeper the soil layer,the less effect from topographic factors.There was a highly significant correlation between elevation and most indices of saline soil.Compared with slope,elevation had a greater impact on the soil salinization degree and the spatial distribution of ions of salt.