西藏土壤阳离子交换量的空间变化和影响因素研究

根据西藏17个土类150个骨干剖面的分析资料,应用统计方法,探讨土壤CEC的空间变化和影响因素。结果表明,在西藏广阔的高原面上,土壤CEC的空间变化具有明显的水平地带特征:从东南向西北,土壤CEC随高山草甸型→高山草原型→高山荒漠型而急剧降低。土壤CEC垂直变化亦有表现,特别是在藏东南地区,山地湿润森林土壤的CEC从基带黄壤向上增高,至暗棕壤和灰化土达到最高,而在森林线以上土壤CEC又随黑毡土→草毡土→寒冻土而降低。西藏土壤CEC的空间变化,主要决定于各类土壤有机质积累的差异;有机质含量较低的土壤,粘粒含量也有重要影响;高山草甸型土壤还受粉砂粒含量的影响。土壤速效钾含量与CEC呈显著正相关,显示了土壤CEC的重要保钾功能。

Spatial Change and Affecting Factors of Soil Cation Exchange Capacity in Tibet

Based on analytical soil data in Tibet, which include 150 profiles of 17 soil types, the spatial change and affecting factors of soil CEC were discussed by statistical method. The result showed that soil CEC had obvious horizon characterics on the vast pleatu. Soil CEC decreased distinctly from southeast to northweast or from the Alpine meadow type, the Alpine steep type to the Alpine desert type. It was in southeast region in Tibet that ver- tical change of soil CEC was also obvious. Soil CEC of mountain wet-forest type soil increased upward from yellow earth in base band, and reached the highest valuable in Dark-brown earth and Podzolic soil. However, above the forest line, soil CEC decreased again form Dark-felty soil, Felty soil to Frigid soil. The spatial change of soil CEC in Tibet was mainly determined by the difference of the accumulation of organic matter. When organic matter content was low, soil CEC was greatly influenced by the clay content. Meanwhile, meadow-form soil in alpine zone was still influenced by silt content. Soil available potassium content had significant positive correlation with CEC, which indicated that soil CEC had important ability to keep potassium.