坡面土地利用格局变化的水土保持效应

摘要

为探明黄土坡面土地利用格局变化的水土保持效应,通过模拟野外坡面土地利用格局,在小区内采用柠条林、坡耕地(豆地)和苜蓿地3种土地利用方式进行空间配置形成不同土地利用格局坡面小区,测定各小区表层0～6 cm土壤水分和土壤体积质量的时空分布特征,并于2007-2008年连续监测各小区产流产沙特性,分析坡面土地利用格局变化的减流减沙效应.Kriging插值结果表明,柠条林、坡耕地(豆地)和苜蓿地3种植被类型混合利用坡面(从坡顶至坡底)小区(包括柠条-豆地-苜蓿小区、苜蓿-豆地-柠条小区、柠条-苜蓿-豆地小区、豆地-苜蓿-柠条小区)土壤表层水分和土壤体积质量呈明显的斑块镶嵌格局,与土地利用结构一致,易于形成径流侵蚀的自我调控系统.相对于单一利用的坡耕地小区,各混合利用格局可以对坡面径流侵蚀有效拦截.其中柠条-豆地-苜蓿小区的年侵蚀模数最低,2年的减蚀率分别达到98%和94%.构建合理的土地利用镶嵌格局是控制水土流失的重要措施之一.%Objective of this study was to understand the soil-water conservation effects of slope land use pattern changes on the Loess Plateau.Korshinsk peashrub, plowland (mung bean) and alfalfa land were selected to develop mixed land use patterns by spatial arrangement.Through two years (2007-2008) field observations, the effects of land use patterns on soil moisture, soil bulk density and runoff-sediment yield were studied in plot scale.Kriging interpolation calculation showed that soil surface moisture and bulk density in mixed land-use pattern plots (including korshinsk peashrub-mung bean-alfalfa plot; alfalfa- mung bean- korshinsk peashrub plot; korshinsk peashrub- alfalfa- mung bean plot; mung beanalfalfa- korshinsk peashrub plot) had apparent characteristics of plaque mosaic pattern, which were uniform with land-use structures and easy to form self-regulation system for runoff-erosion controlling.These land use patterns appeared good effect on absorbing the runoff and trapped sediments, compared to single plowland usage.Korshinsk peashrub-mung bean-alfalfa plot had the smallest annual erosion modulus, and the erosion reduction rate in the two years research reached to 98％ and 94％, respectively.Creating a mosaic pattern by land use arrangement was one of the important measures in controlling soil erosion.