历史时期西北干旱区生态环境演变规律和驱动力

Evolution Laws of the Ecological Environment and Their Driving Forces in the Arid Areas of Northwest China during the Historical Periods

生态环境演变的基本规律是:山前地带引水增加,人工绿洲扩大,生态环境改善,但盐渍化发展;河流中下游水量减少,古代绿洲衰亡,荒漠化扩大,生态环境恶化。景观格局的变化规律是:“两扩大,四缩小”,即在沙漠与绿洲同时扩大的情况下,而处于两者之间的自然水域、林地、草地和野生动物种群减少。引起生态环境变化的驱动力,主要是社会经济发展改变了水资源的地域分配,同时与气候波动、河流改道、风沙活跃等自然因素有关。

The basic evolution laws of ecological environment are that the diverted water volume is increased in the fore-mountain zones, the areas of artificial oases are enlarged, the ecological environment is improved, but the soil salinization becomes more serious; in the middle and lower reaches of rivers, the stream flow is reduced, the decline and fall of paleo-oases occur, desertification becomes more severe, and the ecological environment is degenerated. The evolution laws of landscapes are the “two enlargements and four reductions”, that is, under the enlargements of both deserts and oases, the areas of natural waters, woodlands and grasslands as well as the populations of the wild animals and wild plant communities in the ecotones between the oases and deserts are reduced. The driving forces resulting in the evolution of ecological environment are mainly that the regional distribution of water resources is changed due to the social and economic development, moreover, the evolution of ecological environment is also related to the natural factors, such as the climatic fluctuations, change of river courses and blown sand erosion and deposition.