滨海盐沼及其植物群落的分布与多样性

Coastal salt marshes and distribution and diversity of salt marsh plant communities

滨海盐沼是广泛存在于世界中、高纬度地区的一种湿地生态系统,具有抵御风暴潮灾害、净化污染物和为珍稀濒危生物提供适宜生境等重要的生态和经济价值。滨海盐沼因随高程变化而急剧变化的环境梯度和植物带状分布现象而为生态学者阐释自然界物种的分布机制提供了理想系统。主要概述了滨海盐沼的定义、特点、类型、全球分布以及潮汐作用、土壤盐度等环境因子特征;阐述了不同尺度下滨海盐沼的植物群落分布和多样性特征。在滨海盐沼植物群落的分布特征上,重点阐述了中尺度下的植物带状分布,即植物群落往往在自海向陆渐高的不同高程梯度上表现出显著的分带分布,不同植物各自占据该梯度上的一定区域。通常认为,带状分布是植物竞争和物理性胁迫共同调控的结果,但其在不同地理区域的普适性仍存争议。滨海植物群落多样性往往较低,在中、小尺度上盐沼植物多样性受控于盐度、潮汐等物理性胁迫、植物间相互作用等因子的作用;在大尺度上盐沼植物多样性可能随纬度增大而增加。系统深入地认识滨海盐沼植物群落生态格局和过程,将为气候变化、生物入侵等人类影响下的滨海盐沼生态系统的管理和恢复提供有益经验。

Coastal salt marshes widely distributed at middle and high latitudes of the world are ecologically and economically important for storm buffering, pollutant filtering and providing habitats for rare and endangered species. With striking plant zonation patterns across steep environmental gradients, coastal salt marshes have been considered as ideal systems to investigate mechanisms of species distribution in natural habitats. The present paper introduced the definitions, characteristics, types and global distribution of coastal salt marshes and patterns of environmental factors, such as soil salinity and tidal flooding in salt marshes, and summarized characteristics of plant distribution and diversity at different spatial scales in coastal salt marshes. In salt marshes, plant communities at mesoscale often exhibited pronounced zonation patterns across elevations from the sea to the upland border, with each species dominating a special zone. Such zonation was generally believed to be a product of mediation of both physical stress and plant competition; however, the generality of this paradigm at different geographical sites has been questioned. Plant diversity in salt marshes was generally low, which was suggested to be controlled by physical stressors and plant interactions at fine scales and to increase with increasing latitudes at coarse scales. In future, a more comprehensive knowledge of patterns and processes of salt marsh plant communities will benefit management and restoration of coastal salt marshes which have been being challenged by increasing human impacts, such as climate change, biological invasions and etc.