福建平潭无居民岛屿空间特征对植物多样性的影响

Effects of Spatial Characteristics on Plant Diversity on Uninhabited Islands in Pingtan,Fujian

为了明确岛屿空间特征对植物物种多样性的影响,该研究应用样线法和样方法对福建省平潭主岛周边19座无居民海岛进行植被调查,统计分析每座岛屿的物种丰富度和典型植物群落的Margalef丰富度指数、Shannon-Wiener多样性指数、Simpson多样性指数和Pielou均匀度指数;采用多种函数对种-面积关系进行拟合,并利用冗余分析影响岛屿典型植物群落物种多样性的空间因素,以探究岛屿植物物种多样性的形成与维持机制。结果表明:(1)平潭主岛周边19座无居民岛屿中有12座岛屿以典型的岛屿森林群落为主,有2座岛屿以灌草丛为主且缺乏乔木层,有5座岛屿只有草丛覆盖。(2)19座岛屿的植物物种丰富度均随岛屿面积的增加而增加,当岛屿面积增加到7.184 hm2时,物种数量增加的速率减慢。(3)岛屿的面积、周长、周长面积比、近岸距离是影响物种多样性的主要空间特征,其中岛屿的面积、周长越大,周长面积比、近岸距离越小,岛屿的物种丰富度越高。(4)在岛屿典型植物群落中,乔木层的物种多样性主要受岛屿面积、周长、周长面积比的影响,而灌、草层的物种多样性主要受近岸距离的影响。研究认为,岛屿面积达到7.184 hm2是能够保证大部分常见植物种的生存空间;距离大陆越近的岛屿越有利于物种间的扩散,其物种的迁入率越高,从而使岛屿的物种多样性提高。

In order to clarify the impact of island spatial characteristics on plant species diversity,this study applied the sample line method and sampling method to conduct vegetation survey on 19 uninhabited islands around the main island of Pingtan,Fujian Province,and statistically analyzed the species richness of each island and the Margalef richness index,Shannon-Wiener diversity index,Simpson diversity index and Pielou evenness index of typical plant communities.We used multiple functions to fit the species-area relationship,and used Redundancy analysis to explore the spatial factors that affect the species diversity of typical plant communities on the island,so as to explore the formation and maintenance mechanism of plant species diversity on the islands.The results show that:(1)among the 19 uninhabited islands around the main island of Pingtan,12 islands are dominated by typical island forest communities,2 islands are dominated by shrub and grass layers and lack of tree layer,and 5 islands are only covered by grass.(2)The plant species richness of the 19 islands increased with the increase of the island area.When the island area increased to 7.184 hm 2,the rate of species increase slowed down.(3)The area,perimeter,perimeter area ratio and inshore distance of the island are the main spatial characteristics that affect species diversity.The larger the area and perimeter of the island,the smaller the perimeter area ratio and inshore distance,the higher the species richness of the island.(4)In the typical plant communities of the island,the species diversity of the tree layer is mainly affected by the island area,perimeter and perimeter area ratio,while the species diversity of the shrub and grass layers is mainly affected by the inshore distance.According to the research,the island area of 7.184 hm 2 can guarantee the survival space of most common plant species.The closer the island is to the mainland,the more conducive it is to the spread of species,and the higher its species immigration rate,thus improving the island s species diversity.