海南岛甘什岭热带低地次生雨林物种组成与地理成分

Species composition and geographic elements of the tropical lowland secondary rain forest of Ganshiling,Hainan Island,China

海南岛热带低地次生雨林是不同于热带山地雨林的重要森林类型。在南部甘什岭自然保护区选择典型次生雨林建立3000 m2固定样地，研究了其物种组成和地理成分特征。结果表明：经种-面积曲线印证的2700～3000 m2的取样面积能够反映该雨林类型植被的分布特点。维管植物隶属于64科128属163种，其中蕨类植物6科7属8种，单子叶植物9科16属17种，双子叶植物49科105属138种。优势科明显，单种科和寡种科占总科数的87.50%；属内种数的变化范围为1～5，且单种属最多（105属，占82.03%）。物种丰富度明显低于尖峰岭热带山地雨林，也显著低于云南片断热带雨林，科、属、种的分布区类型均以热带性质占绝对优势，种子植物科、属的热带成分所占比例分别为75.87%和92.56%，种的热带成分高达93.87%，这不同于尖峰岭山地雨林由热带向亚热带/暖温带的过渡性质。

Characteristics of the tropical lowland secondary rain forest, an important forest type in Hainan Island, are different from that of the mountain rain forest. A 3000 m2 permanent plot was established in the lowland secondary rain forest in Ganshiling Natural Reserve and species composition and geographic elements were studied. It was found that vegetation characteristics and distribution patterns could be showed well in the sample size of 2700-3000 m2, which was proofed by the speciesarea curve. The vascular plant species belonged to 64 families, 128 genera and 163 species which included 6 families, 7 genera and 8 species of pteridophyte, 9 families, 16 genera and 17 species of monocotyledoneae, and 49 families, 105 genera and 138 species of dicotyledons. 87.50% of families included only one or 2-4 species and, predominant families were obvious. Moreover, the species numbers in a genus varied from one to five, and the number of those including one species was the biggest accounting for 82.03%. The species richness in the tropical lowland secondary rain forest of Ganshiling was obviously lower than in the mountain rain forest of Jianfengling and the fragment rain forest in Yunnan Province. The tropical element percentages of family, genera and seed plants in the lowland secondary rain forest of Ganshiling were 75.87%, 92.56% and 93.87%, respectively, quite different from those in the Jianfengling mountain rain forest transitioning from tropical to subtropical/warmtemperate types.