松嫩平原环境演变与土地盐碱化、荒漠化的成因分析

STUDY ON THE ENVIRONMENT EVOLUTION AND THE ANALYSIS OF CAUSES TO LAND SALINIZATION AND DESERTIFICATION IN SONGNEN PLAIN

松嫩平原是我国最大的平原之一,百年前还是一个水草丰盛的大草原,自20世纪下半叶以来,盐碱化十分严重,盐碱荒漠化发展迅速,许多地区经20～30年就变成了不毛之地。以往的研究很少涉及地质历史背景,然而,这是一个极为重要的因素。文章以地质历史的演变为基础,从气候因素、人文因素和全球变化等多种因素对松嫩平原苏打盐分的来源、分布与富集规律及盐碱化、荒漠化的形成原因开展综合研究。应用TM卫星遥感数据、3S技术及环境模拟技术对土地盐碱化、荒漠化的分布、扩展进行量化研究,并首次进行了松嫩平原的盐碱荒漠化评价,揭示了该区生态环境恶化的严重性。从而为振兴东北提供了重要的环境信息,为松嫩平原生态环境保护、治理和土地资源的可持续利用提供了科学依据。

The Songnen plain, rich in water and grass a century ago, is one of the biggest plains in China. Since the middle of the 20th century,agriculture and stock raising have been increased rapidly, and it had been built important industry base of energy sources. The land desertification, salinization, and grass degradation had been serious problems as the population increasing and economy developing, and many areas even had changed into slick spot of exposed salina. Based on the evolution of the geological history, integrated analysis on the causes of land salinization and salinized desertification had been done in Songnen plain by many factors, such as climate, humanity and global changes. Applied 3S technology to inspect the dynamic changes of salinized soil and water body, and the result showed that the increasing rate of salinization was 2.38% per year from 1989 to (2001,) and water body decreased at the rate of 3.81%. Evaluation of salinized desertification was done using GIS-EIS coupling technology, and the distribution digital map was drawn, which indicated that the area of salinized desertification in hinterland of Songnen plain was 36.72% to the whole, and Da′an city was even 68.37%. The cause of the land salinization in the Songnen plain was complex that it was neither from the irrigation nor from the eluviation of water to rock salt layer, it suffered from complex geo-environment evolution and social economy development. The abundant soda component in the plain was related to the weathering fragment of granite and volcanic rock, which mostly came from Daxing'anling mountainous region to the west. Since Pleistocene, the Western plain had been the depocenter and the area with the most serious salinization and salinized desertification in present period. Salt in the Songnen plain was enriched in the Holocene epoch, and alkalescence grassland was formed at the end of the epoch. Vegetation and soil covering were destroyed as the activity intensifying of human being, and resulted in the fasten development of salinization and salinized desertification, in which process the global warming effected to a certain degree.