西藏山坡流动沙地物种多样性恢复及影响因素

在2008年建立的雅鲁藏布江中游的山坡流动沙地植被恢复试验基地,选取丘间地和迎风坡2个类型,并随山坡海拔增加布设了4条调查样带,调查了160个样方的植被恢复物种组成与生长状况,分析了物种丰富度、α多样性和β多样性随微地形改变的变化特征,以期为西藏沙地植被及物种多样性恢复提供实践依据。结果表明:2011年山坡流动沙地恢复植被共有14个种,隶属9个科,12个属。Shannon-Wiener指数在4个调查样带之间的变化较大,Simpson指数和Pielou均匀度指数的变化较小,α多样性指数总体上表现为随物种丰富度的增大而增加。丘间地的群落相似性大于迎风坡,在群落梯度上丘间地的物种多样性恢复效果较好。2016年山坡流动沙地平均植被盖度达65.6%,最大达94%,物种丰富度显著提升。局部微地形、恢复植物种的选择是影响山坡流动沙地物种多样性恢复的主要因素,建议通过设置沙障改变局部微地形,或采用沿等高线人工脚踩回头撒播的方法等,以增加山坡流动沙地植被恢复的物种多样性。

Restoration of plant species diversity on valley slope sand dunes and the influencing factors in Tibet, China

Desertification has been described as one of the most critically important global problems. By 2014, the sandification area of Tibet Autonomous Region, China was 21.58×104 km2, and caused immense damages to regional ecological security and local socioeconomic devel-opment. In this paper, the plant species composition and vegetation recovery situation were investigated on sand dunes in the alpine valley slope of the middle reaches of Yarlung Zangbo River of Tibet, China, based on field surveys of four belt transects and 160 quadrats estab-lished on two types of interdune and windward sides of sand dunes, respectively. Firstly, the changes in species richness, αdiversity, andβdiversity were analyzed, and then the influences of elevation, slope, and vegetation coverage on species diversity were explored. The purpose of this study was to provide a practical basis for vegetation and biodiversity restoration on sand dunes in the Tibetan Plateau. The results showed that there were 14 species in the 160 quadrats of vegetation recovery of valley slope sand dunes in 2011, belonging to 12 genera in nine families. In terms ofαdiversity, the change in the Shannon-Wiener index between the four belt transects was relatively large, while the changes in the Simpson index and Pielou evenness index were small. Generally speaking, the αdiversity index presented a similar increas-ing trend with that of species richness. In terms of β diversity, the community similarity of interdunes was greater than that of windward dunes, and from the viewpoint of community gradient, the result of species diversity restoration on interdunes was also better than that of windward dunes. The filed survey in 2016 showed that the average vegetation coverage had reached 65.6％, with the highest 94％. The main factors that influenced the restoration of species diversity were microtopography on valley slope sand dunes and screening for suitable plant species. To improve the species diversity of vegetation restoration, several measures could be used, such as setting a sand barrier to alter the microtopography, using an approach which sows seeds into footprints trampled on sand dunes by feet following the contours of the mountain, or increasing the number of plant species.