中文摘要：

气候变化与人为干扰加剧景观破碎化进程,导致产生一系列相互隔绝的＂生境岛屿＂。本研究以科尔沁沙地流动沙丘18个不同大小丘间低地为研究对象,将丘间低地视为＂生境岛屿＂,探讨＂生境岛屿＂面积对植物种分布格局的影响,并基于此提出物种多样性保护方案。结果表明：物种对生境破碎化的敏感性不同,第I类物种主要分布在小面积岛屿（如乌丹蒿、芦苇、野豌豆）;第II类物种主要分布在大面积岛屿（如胡枝子、画眉）;第III类物种主要分布在中面积岛屿（如刺藜、苦参）;第IV类物种在大岛、中岛、小岛均有分布（如黄柳）;在累加岛屿面积相同时,总物种数为中岛组合〉组合岛〉大岛组合〉小岛组合;沙生植物物种数为组合岛〉中岛组合〉大岛组合〉小岛组合;草甸植物物种数为中岛组合〉组合岛〉大岛组合〉小岛组合;草原植物物种数为组合岛〉中岛组合〉大岛组合〉小岛组合。探讨＂生境岛屿＂面积对植物多样性及其分布格局的影响将为半干旱沙区植物多样性保护提供理论依据。

英文摘要：

Climate change and human disturbance will aggravate habitat fragmentation,resulting in the formation of a series of ＂habitat islands＂. Considering interdune lowlands as the ＂habitat island＂,this study selected 18 interdune lowlands with different sizes in active sand dunes of Horqin Sand Land,to explore the effect of ＂habitat island＂size on plant species distribution pattern and propose different protocols of species diversity conservation. Plant species showed different sensitivities to habitat fragmentation： The type I species mainly distributed in small islands（ such as Artemisia wudanica,Phragmites communis and Vicia amoena）,the type II species mainly distributed in large islands（ such as Lespedeza davurica and Eragrostis pilosai）,the type III species mainly distributed in medium size islands（ such as Chenopodium aristatum and Sophora flavescens）,and type IV species distributed in all types of islands（ e.g.,salix gordejevii）. For given total area of islands,both the total- and meadow species richness were in order of the combination of medium size islands 〉 the combination of different sizes of islands 〉 the combination of large islands 〉 the combination of small islands,while both the species richness of psammophyte and steppe species were in order of the combination of different sizes of islands 〉 the combination of medium size islands 〉 the combination of large islands 〉 the combination of small islands.Therefore,exploring the effects of ＂habitat island＂size on plant species diversity and its distribution pattern will provide theoretical basis for plant diversity conservation in semi-arid sand dunes.