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Chang’an University (2012)

Study on Groundwater Dependent Ecosystem and Ecological Mechanisms of Vegetation Succession in Desert Lake-basin Region

宋国慧; Song Guo Hui

Titre : Study on Groundwater Dependent Ecosystem and Ecological Mechanisms of Vegetation Succession in Desert Lake-basin Region

Auteur : 宋国慧; Song Guo Hui

Grade : Doctoral Dissertation 2012

Université :

Résumé
Water is a valuable resource which all the living things on earth live on. As an importantpart of forming water resource—groundwater, which plays an irreplaceable role in naturalenvironment and human social activities’ sustainable development. Especially in the ariddesert area with scarce precipitation, it is an important part in maintaining ecological balanceof natural vegetation in desert region. Therefore, it is of great significance to deeply probe themechanism between the changes of groundwater ecosystem and natural vegetation’ secological successionThe vegetation’s ecological environment degenerated and land desertification intensifiedin arid desert region with dry climate, scarce precipitation, high evaporation and bad naturalenvironment. In addition to the tectonic and global climate condition changes, the reason isclosely related with the changes in groundwater system. For example, in the northwestern ariddesert region of our country, it takes on a special pattern of geographic space betweenmountains and basins from its geographic distribution characters. Among them the largeendorheic basins mainly include the Hexi Corridor of Gansu Province, Xinjiang Junggar basin,Tarim Basin, Qinghai Basin, Jilantai—Hetao Basin,ect..Due to the extremely dry climate,there appears typical desert landscape in basin’s heart. However, around the basin’s distributesome high ranges such as famous Qilian Mountains, Tianshan Mountains, Kunlun Mountains,Helan Mountains, Yinshan, and so on. And these mountains in the region become the moisturein atmosphere condensed centre in arid regions. With high precipitation providing importantrecharge sources for sand-covered alluvial plains and lacustrine basin groundwater. So,though the ecological environment is harsh in desert lake basin area, there grow many naturalvegetations in the sand–covered Salt Lake near the sand in shallow groundwater, which playan essential role in maintaining ecological environment of this area.This paper chose desert basin area as research object, relying on SEE(Society ofEntrepreneurs&Ecology)Ecological Association Fund Project-Study on the groundwaterresources and its ecological effects in Ulan Buh Desert, taking the area of Jilan Tai lake basin covered by Ulan Buh Desert as an example, carrying out the research on desert basingroundwater ecosystem and vegetation’s ecological succession mechanism throughintegratedly using theoretical analysis, field investigation, means of indoor test. The mainresearch results:1The author put forward the definition of groundwater ecosystem, which refers to thegroundwater and groundwater dependent ecosystem, including groundwater system andgroundwater aquatic plant system. And groundwater systems mainly consist of groundwaterflow system, groundwater formation system and groundwater system biology. Groundwateraquatic plant system means the plant system which lives directly or indirectly on groundwater.2The author studied the conditions of groundwater level rising and falling, the restrictivefunction of groundwater system to desert vegetation ecological system and the adaptationmechanism of desert vegetation’s ecological system to the change of groundwater system.3From the water vertical angle, the author analyzed the transformation relationshipamong groundwater, capillary water and soil water and the contact as well as ecologicalsignificance between desert condensation and groundwater. The author also considered thatthe groundwater in desert-covered lake basin is relatively rich and the groundwater table isshallow. Meanwhile, sandy soil capillary zones generally exist on water table. The uniquedesert hydrological ecosystem in desert basin area consists of capillary fringe together withatmosphere water, plant water, soil water and groundwater. And capillary fringe plays the roleof connection in hydrological ecosystem. At the same time, it is an important link ofhydrological circle in arid region. The characteristics of groundwater dynamic and capillarywater rising decide the conditions of soil water supply in northwestern desert lake basin area,controlling the distribution pattern of desert vegetation divided by species and influencing thestability of existing vegetation and succession trend. But the dynamic of temperature field isthe key factor affecting groundwater, capillary water and soil water’s transformation.4The author clarified the definition of ecological level of groundwater in desert lakebasin and believed that it could meet the requirements of ecological environment, prevent thedegradation of vegetation, land desertification, soil salinization problems and maintain theburied depth of groundwater for azonal natural vegetation growth needed water. And it is alsoa zone to satisfy the needs of plant ecological environment and influenced by the properties of capillary soil with dynamic variations in time and space. Here the author also put forward theamount of optimal groundwater eco-environment’s groundwater depth and capillary which arefit for groundwater aquatic plants to grow.

Mots clés : Desert Lake Basin Area; Groundwater Ecosystem; Capillary Fringe; the WetLayer in Soil; the Optimal Groundwater Eco-environment; Vegetation’s Ecological Succession; Ulan Buh Desert; Jinlan tai Basin;

Présentation (CNKI)

Page publiée le 2 avril 2014, mise à jour le 11 janvier 2018