中文摘要：

物种多度–分布关系是生物多样性科学的关键问题之一,但目前对其解释尚未有统一的观点,生态幅假说和集合种群动态理论是其中两个有代表性的假说。作者以松嫩平原羊草（Leymus chinensis）草甸的代表性群落羊草–杂类草群落斑块为研究对象,分别于2007年和2008年调查了其植物生长型组成和斑块距离,来检验上述两个假说对物种多度–分布关系的解释能力。作者提出以生长型适应指数（growth-form adaption index,GAI）作为生态幅的衡量指标,以最小斑块距离来反映植物的扩散和定居过程。结果表明：在生境尺度上,物种的多度和分布成显著正相关,且多度–分布关系在年际间相对稳定。物种的多度和分布均与植物生长型密切相关,分布广、多度高的物种以根茎型、直立型或分枝型为主,分布窄、多度低的物种以莲座型或刷状根型为主。GAI与物种的多度和分布均成显著线性正相关,少数物种的分布广,多数物种的分布窄,直接支持了生态幅假说。最近斑块距离与物种的多度和分布均成显著幂函数负相关,而群落相似性与斑块距离无显著相关性,因此本结果并未直接支持集合种群动态理论,但扩散过程可能是影响羊草草甸植物群落种多度–分布关系的重要潜在机制之一。

英文摘要：

The species abundance–distribution relationship（SAD） is a key issue in biodiversity science,yet there is no consensus about the mechanism that shape the SAD.The two most widely-recognized explanations are Brown＇s niche breadth hypothesis and metapopulation dynamics theory.To test these two hypotheses on the Songnen grasslands,we investigated plant species growth-form composition and interpatch distance in Leymus chinensis–forb community patches in 2007 and 2008.We employed a growth-form adaption index（GAI）,a measure of species adaptation,as a surrogate for species niche breadth and employed shortest distance to nearest patch to indicate the dispersal and colonization process of plant species.Two-year data showed that a species＇ local abundance was positively correlated with this species＇ regional distribution.Furthermore,the SAD showed no obvious variation among years.Both abundance and distribution of a species were closely correlated with plant growth-form;species with higher abundance and wider distributions were mainly comprised of rhizomatous root,erect grass-like stem,or erect dicot stem growth forms.By contrast,species with lower abundance and narrow distributions were mainly comprised of basal rosette stem or bushy root growth forms.GAI was both positively and linearly correlated with abundance and distribution of a species.A few species were distributed widely,whereas most species were distributed more narrowly.This result directly supports the niche breadth hypothesis.Shortest distance to nearest patch exhibited a negative power-law correlation with both abundance and distribution of a species,whereas no correlation was detected between species composition similarity index and distance of patch pairs,results which failed to support the metapopulation dynamic theory.We argue that dispersal processesmay be an important potential mechanism for shaping the SAD relationship of the plant communities in Songnen Leymus chinensis meadows.