科尔沁沙地流动沙丘植被恢复过程中群落组成及植物多样性演变特征

流动沙丘是科尔沁沙地土地沙漠化的产物之一,植被恢复重建是流沙治理的主要措施。本研究以1996年围封的流动沙丘为研究对象,调查了流动沙丘自然恢复过程中植被组成、物种多样性及土壤性状的变化,并分析了流动沙丘植被与固定沙地植被的物种相似性。结果表明流动沙地自然恢复过程中,一年生植物和多年生植物的物种数变异较大,而在固定沙地2种类型植物的物种数相对稳定。从1996到2000年,Shannon-Weaver多样性指数明显上升,但2000年以后呈微弱的下降趋势,这种下降可能与当时的气候干旱有关。植被均匀度指数的变化与多样性指数的变化相似。土壤有机碳、全氮显著增加,中粗砂含量显著下降,极细砂和粉粒含量明显增加。植被组成的相似性指数和对应分析结果说明,流动沙地植被组成的变化直接反映流动沙地向固定沙地的演替趋势。

Characteristics of species composition and plant diversity in the process of vegetation restoration on moving dunes in the Kerqin Sandy Land

In the semi-arid Kerqin Sandy Land of north China,land desertification is the main cause of vegetation degradation and formation of mobile dunes.An experiment was implemented from 1996 to 2003 to monitor the natural process of vegetation recovery after mobile dunes were fenced.We investigated the plant species diversity and composition in each year of the restoration development.Soil samples from 0-5 cm were taken at 2-year intervals to assess the variations of soil physical and chemical properties with vegetation recovery.Vegetative investigations and soil analysis were carried out in a reference site(stable dunes) to detect similarity of composition between mobile and stable dunes.Colonization of pioneer plant species such as Agriophyllum quarrosum facilitated the invasion and development of other plant species on mobile dunes by ameliorating stressful environmental conditions.With restoration development,species diversity and coverage significantly increased.Variations in time of species composition in mobile dunes showed a trend that is in the direction towards stable dunes communities.Vegetation recovery and development resulted in significant changes in soil properties including increased silt and clay contents,organic C and total N in the 0-5 cm depth on mobile dunes.