玛纳斯河流域扇缘带不同植被类型下土壤物理性质

对生长在玛纳斯河流域扇缘带上的柽柳、盐穗木、白刺、猪毛菜4种植被类型下的土壤物理性质进行了研究.结果表明:在水平方向上,1m剖面内柽柳土壤pH值、全盐含量、土壤容重最小,分别为8.75、0.97g/kg和1.42g/cm3;土壤有机质、含水率、总孔隙度、毛管孔隙度均最大,分别为9.04 g/kg、16.67％、45.57％和36.18％,表明柽柳能够显著降低土壤盐分,改善土壤结构.沿垂直剖面,4种植被类型在表层0-20 cm土壤盐分均达到最高,出现盐分“表聚”现象而形成“盐霜”；随着土层深度增加,含水率和土壤容重均呈显著性升高,土壤有机质、田间持水量、总孔隙度、毛管孔隙度和非毛管孔隙度均呈显著性降低(P＜0.05).相关性分析显示,土壤有机质是引起其他土壤物理性质变化的主要原因.相比空裸地,4种植被覆盖类型1 m剖面内土壤有机质、总孔隙度和毛管孔隙度均呈显著性提高,土壤容重显著性降低,有机质分别提高了162.94％、82.94％、85.59％和27.94％,总孔隙度分别提高了44.90％、20.83％、36.06％和15.80％,毛管孔隙度分别提高了58.27％、30.71％、43.48％和25.72％,土壤容重分别降低了18.86％、10.86％、17.14％和7.43％,表明干旱荒漠区盐碱土上生长的不同盐生植物能够显著改善土壤质量.

Analysis of soil physical properties under different vegetation types in the alluvial fan area of Manas River watershed

Soil physical properties of four vegetation types (Tamarix ramosissima, Halostachys caspica, Nitraria sibirica, Salsola spp.) were investigated in the alluvial fan area of Manas River watershed. The main results showed that in the horizontal direction, soil pH, total salt content and soil bulk density of Tamarix ramosissima were the lowest within the depth of 1m soil profile, and were 8.75, 0.97g/kg and 1.42g/cm³, respectively; while soil organic matter content, moisture content, total porosity and capillary porosity of Tamarix ramosissima were the highest and were 9.04g/kg, 16.67%, 45.57% and 36.18%, respectively. It was shown that the Tamarix ramosissima could reduce soil salinity and ameliorate soil structure significantly. In the vertical distance of soil profile, the total salt content of the four vegetation types in 0-20cm topsoil was the highest among different soil layers, so salinity accumulated in the form of salt efflorescence in surface soil. With the increase in soil depth, soil moisture content and soil bulk density showed significant increase, but soil organic matter content, field moisture capacity, total porosity, capillary porosity and non-capillary porosity were significant reduced(P<0.05). The result of correlation analysis showed that soil organic matter was the main reason resulting in the change of other soil physical properties. Compared with the uncovered ground, soil organic matter content, total porosity and capillary porosity of the four vegetation types within the depth of 1m soil profile were improved significantly, and soil bulk density was reduced significantly, soil organic matter content was increased by 162.94%, 82.94%, 85.59% and 27.94%, respectively; total porosity was increased by 44.90%, 20.83%, 36.06% and 15.80%, respectively; capillary porosity was increased by 58.27%, 30.71%, 43.48% and 25.72%, respectively, and soil bulk density was reduced by 18.86%, 10.86%, 17.14% and 7.43%, respectively. It was shown that different halophytes growing in the saline-alkali soil in arid desert areas can ameliorate the soil quality significantly.