近50a来艾比湖流域生态环境演变及其影响因素分析

Eco-environmental Change and Its Impact Factors in the Ebinur Lake Catchments during the Past 50 Years

新疆艾比湖是典型的干旱区湖泊,具有特殊的湿地干旱生态系统.晚更新世晚期开始,由于气候逐渐变干,艾比湖不断萎缩.20世纪50年代至80年代末,由于湖区人口的激增及其对水土资源的不合理开发利用加速了湖泊干缩的进程;80年代后期至今,随着新疆北部的气候向暖湿转变,以及湖区人口和耕地增长趋缓,艾比湖湖面出现波动扩张态势.从分析湖泊水量变化入手,对比湖区不同类型土壤的理化性状及植物群落特征,讨论了湖区生态系统内部水、土、生物过程变化规律及其关联性,指出要遏制当地生态的恶化,必须采取积极的生态环境保护和建设措施.

The Ebinur Lake of Xinjiang is located in an arid area, being a closed inland lake with a peculiar wetland-arid ecosystem. The shrinking process of the Ebinur Lake can be divided into 4 stages: (1) The period of a natural shrinkage (from the end of the later Pleistocene to the 1950s), when the area of the lake shrunk from 3000 km^(2) to {1 200} km^(2) because the climate gradually became dry during the several decade thousands of years; (2) The period of a rapid shrinking (from the 1950s to the 1970s), when the area of the lake shrunk from {1 200} km^(2) to 520 km^(2) because the population grown greatly and the water and soil resources were exploited in a large scale; (3) The period of a relative stability (in the 1980s), when the area of the lake was kept in about 500 km^(2) owing to less population growth and less reclamation expansion, and a stable supply of runoff and underground water from the main rivers to the lake; (4) The period of a new expansion (from the later 1980s to 2002), when the area of the lake increased, in a fluctuant way, to about {1 000} km^(2) because precipitation increased, followed by a water supply increase. The change of hydrological state has brought a significant impact on the structure and function of the wetland ecosystem of the Ebinur Lake catchments, including the changes of the non-biological factors, such as soil, water, temperature et al. and the biological factors, such as animal, plant et al. The Lake shrinking weakened its ecologic function which is as a good living habitat for animals and can adjust the local climate and moisture cycle and slow down blown sand. It is clear that the naked, dry, loose and salty lakebed is the source of sand-dust. Since the later 1980s the fluctuant expansion of the lake s area has made the azonal vegetation recovery in the marginal zone of alluvial-fluvial fans and the area where the river water joins into the lake, but the degradation status of the zonal vegetation in the surrounding area did not get better. The coupling relationship between human activities and the natural environment in the lake area shows that positive measures of eco-environmental protection and construction must be adopted to control and prevent the local ecological deterioration.