地表物质组成与土地沙漠化

土地沙漠化是在干旱、半干旱地区,由于特定的自然条件和人类不合理地利用自然资源,所引起的环境退化过程。随着这个过程的进一步发展对人类的不利影响越来越大。因此,对土地沙漠化的问题,也越来越得到人们的普遍重视。在内蒙伊克昭盟及宁夏、陕北地区,沙漠化的土地面积,分别占总土地面积的32%、25.2%和45.9%。这说明了在上述地区土地沙漠化是相当严重的。造成土地沙漠化的自然因素,除气候的干旱、多风外,地表物质的组成是其物质基础。而地表物质组成与沉积条件密切相关,因此,不同的沉积环境形成不同的沉积物,其质地性质差异很大。这些不同的沉积物,对土地沙漠化的发生及发展速度、类型和治理措施都有直接关系。因此,研究地表物质组成与土地沙漠化之间的关系是极为重要。

Surface Material Composition and Desertification

The locse surface material composition of sandy land is one of the important natural factors in the formation of desertification,especially when the sand particles account for about 75% of the total mechanical composition. There has been a few patches of shifting dunes in the Ningxia-Shaanxi loess hilly region but their total area is very limited.In the sections occurring shifting sands the fine sand particles constitute more than 60 per cent in soils while in the vast area of loess hilly region no shifting dunes occur,because the average sand particles amount to only 34.6 per cent. They only occur in local places where the sand particles account for more than 60 per cent.