中国西部干旱区生态环境演变过程

Eco-environmental Evolution in Arid Area of West China

根据湖沼沉积、黄土沉积和冰积等地质记录,运用地理信息系统、遥感、生态景观学等方法,从万年、千年和百年及百年以下四个时间尺度对中国西部干旱区生态环境演变过程进行研究。结果表明,全新世以来,中国西部干旱区的气候变化经历了多次的相对暖干和相对冷湿交替变化,变化历程较为复杂。早全新世、中全新世、晚全新世气候特点因地因时而异,但总体特征以干旱化为主,280～350a来,降水量有明显的减少趋势,并表现出显著的周期性。但在近半个世纪以来,中国天山地区的气候变化特征表现为气温升高,降水量增加。总的来说,从20世纪80年代以来,新疆的气候趋于好转,植被覆盖状况改善明显,山地森林、草甸、人工绿洲的面积均呈增加趋势。研究结果还表明,在一定尺度的气候背景条件下,地表的植被覆盖对调节绿洲区域气候有着积极的作用,可增加局部地区的降水。

The eco-environmental evolution in arid area of West China were studied at (1 0000)-year, 1000-year, 100-year and 10-year timescales, based on geological data of lacustrine, eolian and glacial deposits, and by using the methods of GIS, RS and landscape ecology etc. The results showed that the climate changing patterns had gone through several complex cycles of 'warm and dry' and 'cold and moist' periods. Although the climate pattern varied spatially and temporally during the earlier, the mid and the late Holocene period, there was an overall tendency of becoming drier. Over the past 280～350 years, the precipitation decreased significantly and periodically. Over the past half of a century, the climate pattern over Tianshan Mountains tended to increases in both temperature and total precipitation. From the 1980s to the end of this century, the regional climate in Xinjiang region seemed to become colder and moist, accompanied by increases in green vegetation cover, total areas of forests, grasslands, and oasis. The results also indicated that increases in vegetative cover tend to have positive impacts on regional climate increases in total precipitation over some geographic areas at different spatial and temporal scales.