黄土塬区土地利用方式对土壤大孔隙特征的影响

Impact of land use types on soil macropores in the loess region

土壤导水率及大孔隙数量是决定降雨-入渗的重要参数,对模拟土壤水分及溶质运移、建立流域水文模型具有重要意义.为确定黄土区土地利用方式对土壤大孔隙特征的影响,本文通过Hood入渗仪及土壤水分特征曲线,比较了该区刺槐林地、草地、小麦地、苹果林地土壤导水率、大孔隙度和大孔隙连通性的差异.结果表明:研究区刺槐林地、草地、小麦地、苹果林地的平均饱和导水率分别为58.60×10-6、54.90×10-6、35.30×10-6、23.40×10-6m·s-1,存在显著性差异.不同土地利用方式下的单位面积有效大孔隙数目、大孔隙度及大孔隙连通性均依次为:刺槐林地≈草地>小麦地>苹果林地.植被恢复通过植物根系穿插、土壤动物活动等形成大孔隙,可显著提高土壤入渗性能.黄土区应坚持林草植被恢复措施.

Soil hydraulic conductivity and macropores are important parameters for determining the proportion of precipitation infiltration, simulating soil water and solution transport and establishing the hydrologic model. To investigate the effect of land use types on maeropores in soils, soil hydrau- lic properties, macroporosity and macropore connectivity under different land use types （locust forestland, grassland, farmland and apple forestland） in the loess region were measured by Hood infihrometer and water retention curve. The results showed that the average hydraulic conductivities under locust forestland, grassland, farmland and apple forestland were 58.60×10^-6, 54.90× 10^-6, 35.30×10^-6, 23.40×10^-6 m · s^-1 , respectively. The differences among land use types were statisti- cally significant （P〈0.05）. The effective macropores per unit area, maeroporosity and macropore connectivity were highest in locust forestland and grassland, followed by farmland and apple forest- land. As a consequence of vegetation restoration, macropores which developed by plant roots and animal activity had significantly improved the soil infiltration capability. Restoring woods and grasses should persist in the loess region.