榆林毛乌素沙地飞播植被对流动沙丘链的逆转作用

THE CONVERSING EFFECT OF AERIAL SEEDED VEGETATION ON THE MOVING SAND DUNE CHAINS IN YULIN AREA OF MAOWUSU DESERT

本文系1988年在榆林毛乌素沙地,采用4个梯度,56个测风探头,对流动沙丘和飞播地进行风速的同步或相对值观测报告。测试阐明:飞播形成的植被踏郎(Hedysarum mongolica TUrcz)与花棒(Hedysarum scoparium Fisch et Mey.),尤以踏郎对流动沙丘的逆转作用效果显著。由于踏郎地下茎的萌生,使原来24m宽的植被带扩大到40m;10a后保存面积由17.7％增到60％以上,形成固定沙地。 改造后的沙丘,不仅坡度减小、坡长增大,沙丘高度显著降低,并呈“舌状”前移,丘间地也不断缩小等,出现一系列飞播地的地貌形态变化,使“水平”、“垂直”风速的降低值均衡。对比封禁十年后的流动沙丘,除沙丘前移外,坡面上仍然寸草不长。因此,提倡远处飞播,近处人工直播是改造沙漠的有效措施。

The measurements of synchronous and relative value of wind velocity were conducted with 56 probes of 4 levels in aerial seeding land and moving dunes in Yulin area of Maowusu Desert in 1988. The result showed that the conversing effect of aerial seeded Hedysarum mongolica Turcz. and Hedysarum scoparium Fisch et Mey., especially that of H. mongolica was remarkable. The former vegetation belt was widened from 24 metres to 35 metres because of germination of the subterraneous stem. The rate of survival area increased from 17.7% to more than 60% 10 years later and the land changed into stablized sand land.As for the reformed dune, its slope became smaller, its length became longer, its height became lower, it went forward in a tongue-shaped form and the land between dunes became smaller. A series of changes of the topographic features of aerial seeding land occurred. The wind velocity there was reduced horizontally, vertically and harmoniously. That the result of closing the moving dune after 10 years was still without vegetation on slope but the dune went forward. Thus, aerial seeding in the farther place and artificial seeding in the near place are considered to be good methods to control the dunes. It should be promoted in the future.