鄂尔多斯盆地堡寨淖湖盆系统生态环境变化的驱动力

Drivers of ecological environment changes in the Baozhainao lake-basin system,Ordos Basin

在干旱半干旱地区,湖盆生态系统是流域安全屏障的重要组成部分,在维持生态格局稳定性方面具有重要作用。然而,近年来湖盆生态环境逐渐退化,其变化过程伴随着复杂的动力学机制。为探究湖盆生态环境空间变异及其驱动力,以鄂尔多斯盆地毛乌素沙地堡寨淖为研究区,采用原位动态监测、样方调查、统计分析与数值模拟相结合的方法,分析了堡寨淖湖盆地区典型植被的分布特征,揭示了地下水文过程与湖岸生态系统的互馈机制。结果表明,堡寨淖湖盆生态系统由4种分带类型组成,分别是湖泊带、湖泊近岸波动带、湖岸滩地带和湖岸风沙滩地带,地下水位埋深从湖泊带至湖岸风沙滩地带呈逐渐增大的趋势,植被类型由喜水耐盐植物过渡到耐旱植被,证实湖岸植被的存在显著地影响地下水流系统的循环模式,湖泊与地下水转化主要发生在局部水流系统,造成地下水对湖泊补给量明显减小。研究结果可以为旱区湖泊波动带-风沙滩地带植被物种多样性以及植被生态系统的修复与保护提供科学依据。

In arid and semiarid regions,lake-basin ecosystems are an important part of watershed security barriers,playing an important role in maintaining the stability of ecological patterns.However,the ecological environment of the lake-basin system has been gradually degraded in recent years,and its change process is accompanied by a complex dynamic mechanism.In the present study,we explored the spatial variability of the ecological environment of the lake-basin system and its drivers by taking Baozhainao Lake in the Mu Us Sandy Land of the Ordos Basin as the study area.In-situ dynamic monitoring,sample survey,statistical analysis and numerical simulation were employed.The distribution patterns of typical vegetation in the basin were determined and the mechanisms underlying the mutual feedbacks between subsurface hydrological process and lakeshore ecosystem was explored.The results show that the Baozhainao lake-basin ecosystem consists of four zoning types,namely,the lake zone,the lake nearshore fluctuation zone,the lakeshore beach zone,and the lakeshore wind beach zone.From the lake to the beach zone,the depth of water table increased gradually and the vegetation type transitions from water-loving and salt-tolerant to drought-tolerant.It was further found that the presence of vegetation on the lake shore significantly affects the circulation mode of the groundwater flow system.The conversion between lake and groundwater occurs mainly in the local groundwater flow system,resulting in a significant reduction in groundwater recharge to the lake.The results of this study can provide a scientific basis for the restoration and conservation of plant species diversity and vegetated ecosystems in the lake nearshore fluctuation zoneand lakeshore wind beach zone in arid regions.