海南岛3个林区热带云雾林植物多样性变化

Patterns of plant diversity within and among three tropical cloud forest communities in Hainan Island

以分布在海南岛西部(霸王岭国家级自然保护区,21个样方)、西南部(尖峰岭国家级自然保护区,12个样方)和中部(黎母山省级自然保护区,15个样方)的热带云雾林为研究对象,研究α及β物种多样性、功能多样性、谱系多样性的变化,为植物多样性的保护提供科学依据。结果表明:尖峰岭群落树木个体多度、物种丰富度最大,黎母山群落树木个体多度、物种丰富度最小;黎母山群落间物种组成差异最大,霸王岭群落间物种组成差异最小,海南岛霸王岭(西部)、尖峰岭(西南部)和黎母山(中部)3个林区热带云雾林物种多样性差异可能与空气温度和相对湿度有关。尖峰岭群落内功能丰富度、Rao’s二次熵最低,功能均匀度最高,群落间平均成对性状距离最小,反映群落构建主要受环境筛影响;霸王岭群落Rao’s二次熵最高,功能均匀度最低,群落间平均成对性状距离最大,反映群落构建主要受限制相似性影响;黎母山群落内功能丰富度最高,群落间平均最近性状距离最大,表明限制相似性在黎母山热带云雾林群落构建中的作用更重要。霸王岭群落内谱系多样性、物种间平均最近相邻谱系距离均较大,反映物种间谱系关系趋于发散;黎母山群落内谱系多样性、物种间平均成对谱系距离及群落间平均成对谱系距离均最小,反映物种间谱系关系趋于聚集;而尖峰岭群落内物种间平均成对谱系距离、群落间平均成对谱系距离最大,但物种间平均最近相邻谱系距离最小,反映物种间谱系关系既具有发散又具有聚集的共存格局。因此,海南岛热带云雾林群落植物多样性变化格局与环境及物种间相互作用有关。

Aims We explored α and β species diversity, functional diversity and phylogenetic diversity distribution patterns in three tropical cloud forests along environmental gradients in air temperature and precipitation. Methods We sampled plots in three tropical cloud forests which are located in the west（Bawangling, 21 plots, BWL）, the southwest（Jianfengling, 12 plots, JFL）, and the central of Hainan Island（Limushan, 15 plots, LMS）. We collected species data and functional trait data including plant height, specific leaf area, chlorophyll content, leaf thickness and wood density. We assessed the differences within- and among-community species diversity, functional diversity and phylogenetic diversity in these three tropical cloud forests using the Kruskal-Wallis test. Important findings The tropical cloud forests in JFL had the highest species abundance and richness whereas the lowest in LMS. However, the Bray-Curtis and Jaccard dissimilarity coefficients showed the opposite distribution patterns（i.e. the highest in LMS whereas the lowest in BWL）. Distinct distribution patterns in species diversity across the three tropical cloud forests may be explained by the air temperature and relative humidity. The functional evenness（FEve） within communities was the highest while functional richness（FRic）, Rao＇s quadratic entropy（Rao Q） and the mean pairwise trait distance among communities were the lowest in JFL, indicating that habitat filtering plays an important role in community assembly. BWL had the highest Rao Q and mean pairwise trait distance among communities, and the lowest FEve, which demonstrated that limiting similarity would be prevalent in forest communities assembled. LMS had the highest FRic within communities and mean nearest trait distance among communities, leading to a limiting similarity influencing forest communities. BWL had the highest Faith phylogenetic diversity（PD） within communities and mean nearest phylogenetic distance among communities, reflecting an overdispersed pattern in phylogenetic structures. LMS had the lowest PD and mean pairwise phylogenetic distance within and among communities, suggesting that a clustered pattern in phylogenetic structures. The mean pairwise phylogenetic distance within and across communities were the highest in JFL while the mean nearest phylogenetic distance within communities was the lowest, indicating that phylogenetic clustering and overdispersion patterns co-occur in this forest. We conclude that both plant species interactions and environmental filtering determine the distribution patterns of plant species diversity, functional diversity and phylogenetic diversity both within and among three tropical cloud forests in Hainan Island.