刚察县不同植被类型的土壤水分特征研究

通过对土壤的物理性质和水分特征曲线的测定,分析了刚察县4种植被类型土壤的持水性能和供水性能。结果表明,不同植被类型土壤水分特征曲线与Van Genuchten模型非常符合,R2值都高达0.99以上,说明用Van Genuchten模型描述不同类型土壤水分数量和能量之间的关系是比较准确的。不同植被类型土壤的物理性黏粒含量为:油菜地>高草地>草灌地,土壤容重为:高草地>草灌地>油菜地,而总孔隙度为:油菜地>草灌地>高草地,表明油菜地土壤水分物理性质明显优于草灌地和高草地。土壤持水能力随着土壤吸力的增加而呈现先急剧递减后变化平缓的趋势,不同植被类型土壤持水能力为:高草地>草灌地>油菜地。通过改善土壤结构,增加土壤密度和降低土壤总孔隙度等改善土壤物理性质的措施能对其持水性能产生积极作用。土壤供水能力随着土壤吸力的增加而递减,低吸力段高草地和稠密草灌地的土壤供水性能均优于油菜地和稀疏草灌地,而高吸力段油菜地和稠密草灌地的土壤供水性能优于高草地和稀疏草灌地,表明高草地和稀疏草灌地植被极易受到干旱的威胁。

Characteristics of Soil Moisture for Different Types of Vegetation in Gangcha County

Water retention and supply for four types of vegetation in Gangcha County were analyzed through the determination of soil physical properties and soil water characteristic curve.Results indicate that soil water characteristic curves for four types of vegetation are well in accordance with Van Genuchten model and the values of R2 are greater than 0.99,which indicate that Van Genuchten model may exactly describe the relationship between quantity and energy of soil moisture.The contents of physical clay are in the decreasing order of rape land>tall grass land>grass and bush land;soil bulk densities,tall grass land>grass and bush land>rape land;and soil total porosities,rape land>grass and bush land>tall grass land.The result shows that soil physical properties for rape land are better than those for other two lands.Soil water retention increases with the increased soil suction and presents a trend of abrupt decrease in first stage to gentle change in latter stage.Soil water retentions for different vegetation types are in the decreasing order of tall grass land>grass and bush land>rape land.Soil water retention can be effectively enhanced with the practices that improve soil physical properties by improving soil structure,increasing soil bulk density and reducing soil total porosity.Soil water supply decreases gradually with increased soil suction.Soil water supply at low soil suction for dense grass and bush land and tall grass land is obviously better than that for rape land and thin grass and bush land,while soil water supply at high soil suction for dense grass and bush land and rape land is obviously better than that for tall grass land and thin grass and bush land.These show that the vegetation on tall grass land and thin grass and bush land is easily threatened by drought.