Study On The Dynamic And Stability Of Soil In Artificial Oasis In Ulbuhe Desert

Artificial oasis located in the northeast of ulanbuhe desert was established on the basis of the Yellow River diversion river irrigation system. Surrounded by the outer desert environment, the oasis are affected seriously, especially the harm of sand storm. Water resources, the most fundamental production condition in acid areas, should be reasonably utilized in bid to optimize the integration of biological resources and natural conditions, and then reach full productive potential of living resources and natural systems. Circumjacent natural desert vegetation is not only the environmental and biological foundation, but also organic components of security system of the oasis, which can butter the threat of desert. The desert ecosystem evolved for long time and the change first was reflected in the success and fluctuation of plant community, which has important reference value for the future trend forecast. Based on the research to the buried depth of groundwater, water quality changes, spatial pattern of peripheral vegetation and species diversity of plant community, we can draw the following conclusions:(1) Since the inception of oasis construction in 1979 to 2007, the buried depth of groundwater level rises from 8.28 m to 2.99 m, and the salinity increases to 1.42 g/L from 0.82 g/L. There is significant linear relationship between buried depth and mineralization of groundwater. With underground water level unceasingly rising up, the degree of mineralization goes up continuously, and the water quality gradually improves accordingly.(2) In the process of the oasis operation, soil quality have been improved obviously, and soil plenary nutrients, rapidly-available nutrients generally rise up, while the surface soil salinity and PH value decreased significantly. Soil quality improvement will lay the foundation for high and stable yields of agriculture in artificial oases and sustainable operation.(3) Under the background of regional acid climate, species composition, coverage and diversity of vegetation differ at the irrigation water level. In different gradients from oases to desert, vegetation presents regular distribution( the oasis→Nitraria tangutorum community→白刺十油篙(油蒿)群落→Artemisia ordosica Community→籽篙→沙竹群落) Reasonable artificial planting on the edge of the oasis will improve the environment, promote intrusion and succession of local plant, or it will cause short-term recession and even death. But Artemisia community can complete community succession in a short period. Compared with natural shrubs, artificial shrubberies have low diversity and evenness, high degree of dominance, which indicates poor stability of artificial vegetation. As to this problem, recovering fragmented environment to relatively stable natural ecotone is an effective way.(4) Reasonable utilization of water is the fundamental of eco-environmental construction of the oasis. Ecological construction and economic development shall be considered as high water consumption systems. It is vital to ensure the minimum water supply to ecological protection. Regardless of surface or ground water conservancy construction, the amount of eco-construction water should be counted in, with special attention to reduce the influence on the ecotone. The ecological environment of the oasis depends on the situation of water resources utilization to a large extent. Concerning such problems as severe waste, unbalanced distribution of water, low benefit and poor guarantee, further effective measures must be implemented to strengthen comprehensive management, to develop and rationally layout water conservancy project and water reasonable configuration, according to the need of ecological. Meantime, on the basis of water-saving in combination with the increase of water, ensure the water use of agriculture and ecology to maintain and restore the structure and function of the ecological system.