中国绿洲化及其研究进展

Oasification of Northwestern China:A Review

绿洲化是干旱区人与自然因素共同作用下荒漠向绿洲转变的过程。中国绿洲面积从20世纪50年代初期的20 000km2扩展到2000年的86 000km2,扩大了3.3倍。绿洲化过程不仅伴随着景观格局的变化,而且会引发土壤、生物、气象和水文等要素的变化。分析了近2 000a来中国干旱区绿洲的演变过程,评述了绿洲化过程中景观变化、其对绿洲稳定性的影响及绿洲化过程中土壤要素、气象水文要素变化等诸多方面的研究进展,同时提出未来的研究中应加强绿洲化过程研究框架的建立、绿洲化过程中关键因素变化及绿洲化关键过程研究。

Oasification is the process opposite from desertification,and usually means the restoration-either natural or anthropogenic-of water and life,to a desert.The most significant characteristic of oasification is an increase in vegetation coverage and biomass production.The area of oasification in China reached 8.6×104 km2 in 2000,up from2×104 km2 in the early 1950 s,or an increase of 330%in the past 60 years,largely attributable to the expansion of cultivated land.Through this oasification,both human habitat and environmental quality have been greatly improved in this region.However,the process of oasification has also transformed the original landscape patterns,and more importantly,led to characteristic changes in the soil quality,biological organisms and their interactions,weather patterns and hydrology of this region.This study analyzed the evolution of oases in arid north China over the last two millennia;specifically,we reviewed the landscape changes that have occurred and their potential effects on oasis stability.We posit that a research framework for the investigation of the potential impact of oasification on the sustainability of arid ecosystems should be built in the near future,and that the key factors and processes involved in oasification should be identified and carefully studied.