雅鲁藏布江高寒河谷流动沙地适生植物种筛选和恢复效果

通过4a的人工模拟飞播试验研究(2008—2011年),观测了北方优良沙生植物种和西藏乡土沙生植物种在雅鲁藏布江中游高寒河谷流动沙地上的出苗、保存、生长和繁殖情况,筛选和确定了西藏高寒流动沙地人工模拟飞播的适生植物种。结果表明:籽蒿、花棒、沙拐枣、杨柴和砂生槐在高寒河谷流动沙地的适应性较好。籽蒿在播后第2年便有花序和种子出现,花棒和沙拐枣在第3年开花结实,籽蒿、花棒和沙拐枣均能完成生活史。籽蒿的再繁殖能力较弱,花棒和沙拐枣的再繁殖能力较强。不同类型沙丘的形态特征对人工模拟飞播效果影响较大,最适宜型(第Ⅰ类)流动沙地的人工模拟飞播效果最好,植被盖度达35%;较适宜型(第Ⅱ类)流动沙地的效果较好,植被盖度达30%;不适宜型(第Ⅲ类)流动沙地的效果最差,植被盖度尚不足10%;基本适宜型(第Ⅳ类)流动沙地的效果较差,但采用沿等高线人工脚踩回头撒播法,植被盖度可达20%。不同沙丘部位的人工模拟飞播效果差异明显。

Screening trial for the suitable plant species growing on sand dunes in the alpine valley and its recovery status in the Yarlung Zangbo River basin of Tibet, China

There was a total of 273 697.54 hm² of aeolian sandy lands in the Yarlung Zangbo River basin of Tibet in 2008. The fast development of aeolian sand lands has caused immense damages to its social and economic development, it is urgent to choose appropriate plant species for vegetation restoration of the moving sand dunes in the basin. Thus, we carried out a continuous trial of the field artificial seeding on sand dunes in the middle reaches of the Yarlung Zangbo River basin, the main testing plant species included the northern China's psammophyte species and the Tibet's native species. The germination, emergence, growth processes and reproduction of the testing plant species were observed from 2008 to 2011, based on these, the best suitable species on sand dunes in the alpine valley were determined, which could be used to guide the ongoing vegetation recovery and reconstruction on aeolian sandy land in the studied area. The results showed that the plant height and plant size growth of northern China's psammophyte species were larger than that of native psammophyte species in the field artificial seeding trial, and the species such as Artemisia sphaerocephala, Hedysarum scoparium, Calligonum mongolicum, H. fruticosum var. mongolicum and Sophora moorcroftiana all exhibited good adaptability to moving sand land. So far as the status of reproduction of the testing species, Artemisia sphaerocephala began to flower and seed in the second year, while H. scoparium and C. mongolicum began to flower and seed in the third year, it was the most important finding that A. sphaerocephala, H. scoparium and C. mongolicum were all able to complete the life cycle in the alpine valley under the special climate zone on the Tibetan Plateau, however, the reproducibility of A. sphaerocephala was weak, but H. scoparium and C. mongolicum both showed strong reproducibility. The morphological characteristics and different parts of sand dunes influenced the trial results of field artificial seeding greatly, and the vegetation coverage varied from 5% to 40% on different sand dune types. The approach which sowed seeds into footprints trampled on slope sand land by feet following the contours of mountain artificially proved to be a good measure to improve the results of field artificial seeding trial. The observed results showed that habitat conditions such as precipitation, soil temperature of sand dune, soil moisture content and sand movement affected the germination, emergence and plant growth greatly, but these need to be discussed in detail in the next step.