土壤干化的水文生态效应

应用土壤-植被-大气传输模型(SVAT-model)——CoupModel,对黄土丘陵沟壑区农地(马铃薯)、林地(刺槐林)、采伐迹地(刺槐被砍伐)和荒草地(天然灌草)的土壤水分变化进行了模拟。分析了不同植被覆盖条件下土壤干化程度、气候干旱和植被耗水对土壤干化的贡献率以及土壤干化的水文生态效应。研究结果表明:农地不存在土壤干化现象,刺槐林地、采伐迹地和荒草地均存在明显的土壤干层,以刺槐林地最为严重;气候干旱和植被过度耗水对土壤干化的贡献率分别为70.74%和29.26%,气候干旱是导致土壤干化的主要原因;土壤干化可以导致土壤剖面水分交换深度变浅,土壤剖面水分的移动性变差,使土壤水库丧失77.58%~93.55%的调节能力,形成土壤水分循环的隔离层,增加植被生长对年度降水的依赖性。总之,土壤干化恶化了陆地土壤水文循环环境,影响植被的正常生长,不利于黄土丘陵沟壑区的生态环境建设。

Hydro-Ecological Effect of Soil Desiccation

The changes of soil water of farmland(potato),woodland(acacia),cutting blank and grassland were simulated with SVAT-model(e.g.CoupModel) in loess hilly and gully region.In this paper,the degree of soil desiccation,contribute of climate drought and exhausting water by vegetation to soil desiccation and the hydro-ecological effects of soil desiccation were analyzed.The result showed there was soil desiccation in farmland and no soil desiccation in acacia woodland,cutting blank and grassland and especially soil desiccation were very serious in acacia woodland.The contribute ratio of climate drought and exhausting water by vegetation to soil desiccation were 70.74%,29.26% respectively,thus drought of climate is the main reason of soil desiccation.The soil desiccation can deal to the exchanged layer of soil water in profile shallow,mobility of soil water poor,and lose 77.58%~93.55% of regular capability of soil reservoir,form the isolation layer of water cycle,reinforce the dependency of vegetation to precipitation.In conclusion,the soil desiccation deteriorated the environment of hydrological cycle in the earth,affecting the natural growth of vegetation,making against ecological construction in loess hilly and gully region.