藏东横断山区业拉山背风坡土壤理化性质垂直地带性分析

Vertical zonation of soil physical and chemical properties in the leeward slope of the Yela Mountain in the Hengduan Mountain area in eastern Tibet

【目的】对业拉山背风坡不同海拔梯度表层土壤理化性质的垂直地带性进行分析,为区域干凉河谷地带土壤抗侵蚀评价及植被恢复提供参考。【方法】以业拉山海拔3200~4600 m的土壤为研究对象,测定其体积质量、孔隙度、田间持水性、有机质含量,并分析海拔及各指标间的相关性。【结果】不同海拔土壤的理化性质存在一定差异。不同海拔土壤有机质含量、体积质量、总孔隙度、毛管孔隙度、饱和含水率、毛管含水率和田间持水率分别为14.78~198.96 g/kg,0.43~1.45 g/cm3,55.51%~89.25%,42.64%~81.13%,38.52%~201.61%,30.19%~184.85%和23.07%~175.25%。随着海拔的升高,土壤体积质量、非毛管孔隙度总体呈减小趋势,有机质含量、总孔隙度、毛管孔隙度、饱和含水率、毛管含水率、田间持水率总体呈增大趋势。海拔与土壤体积质量、非毛管孔隙度极显著和显著负相关,与总孔隙度和毛管孔隙度极显著正相关(P<0.01),与饱和含水率、毛管含水率、田间持水率和有机质含量显著正相关(P<0.05)。【结论】业拉山背风坡表层土壤结构以海拔4400 m地区最优,海拔4200和4600 m地区优于海拔3800和4000 m地区,海拔3200~3600 m地区最差。从土壤类型看,业拉山背风坡表层土壤理化性能综合表现为黑毡土>棕壤>褐土>灰褐土。

【Objective】This study analyzed physical and chemical properties of surface soil at different elevation gradients in the leeward slope of the Yela Mountain to provide basis for soil erosion resistance evaluation and vegetation restoration in regional dry cool valley.【Method】The bulk density,porosity,field capacity,organic matter content of gradient soils at different altitudes from 3200 to 4600 m in the Yela Mountain were determined,and the correlation between altitude and indexes was analyzed.【Result】The physical and chemical properties had certain differences at different altitudes.According to different altitudes,the soil organic matter content,bulk density,total porosity,capillary porosity,saturated water content,capillary water content and field capacity were 14.78-198.96 g/kg,0.43 g/cm3-1.45 g/cm3,55.51%-89.25%,42.64%-81.13%,38.52%-201.61%,30.19%-184.85%and 23.07%-175.25%,respectively.As the altitude increased,soil bulk density and non-capillary porosity generally decreased,while organic matter content,total porosity,capillary porosity,saturated water content,capillary moisture content and field capacity generally increased.There were significantly negative correlations between altitude and soil bulk density,non-capillary porosity,and significant positive correlations with total porosity and capillary porosity(P<0.01).There were positive correlations between altitude and saturated water content,capillary water content,field water holding capacity and organic matter(P<0.05).【Conclusion】The structure of surface soil was optimal at 4400 m,better at 4200 and 4600 m than at 3800 and 4000 m,and the worst at 3200-3600 m.The physical and chemical properties of surface soils were in the order of dark felty soils>brown soils>cinnamon soils>grey-cinnamon soils.