北热带喀斯特森林木本植物花性状及其生境分异

植物花性状的多样化是植物长期进化及自然选择的结果, 不同植物种间花性状的变异与生境存在一定的相关性。北热带喀斯特季节性雨林具有生境异质性强、群落结构复杂、特有成分丰富等特点, 分析该森林植物性状的变化特征及其与生境的关联性, 有助于理解物种共存、协同进化过程和对生境的适应, 可为阐明喀斯特植物的生态适应性、理解生物多样性维持机理提供依据。本研究在弄岗15 ha森林动态监测样地木本植物开花相对集中的时间段进行, 记录并分析了21个物种花性状的变化。根据物种空间分布及其与生境的关联特性, 将21个物种分成偏好谷底、山坡、山顶的3种类型, 分析了这3种类型植物的花性状差异; 另外又根据花性状对21个物种进行聚类分析, 探讨了聚类分组结果和根据偏好生境分组结果的异同。结果表明: 花大小、花色鲜艳度均与物种优势度存在显著的负相关关系, 花小而不鲜艳的物种在群落中更有优势, 表现出更好的适应性; 不同偏好生境的植物花色明度有显著差异, 其他的花性状差异不显著; 聚类分组与根据偏好生境的分组有较好的一致性, 反映出物种的花性状变化响应了生境的变化。综上结果, 我们认为北热带喀斯特季节性雨林植物花性状与物种的优势度及生境条件有密切联系, 在该区域中生境对花性状的影响可能比传粉者更为深刻。

Floral traits of woody plants and their habitat differentiations in a northern tropical karst forest

The diversification of floral traits is the outcome of evolution by natural selection, and the variation in floral traits between species has a certain correlation with the plant habitats. The northern tropical karst seasonal rain forests have a great habitat heterogeneity, a complex structure of plant community, and abundant endemic components. Analyzing the relationship between the variation of plant traits and their habitats in those forests is helpful to understand species coexistence, coevolution and their adaptations to habitats, and to provide clues for revealing the ecological adaptability of plants and the maintenance mechanisms of biodiversity in karst forests. We conducted a preliminary study at a 15 ha plot of the northern tropical karst seasonal rain forest in Nonggang to examine the differences in floral traits among species and how these traits varied with habitats, when a relatively large number of woody plants bloomed synchronously, with a total of 21 species being found flowering. We divided the 21 species into three preferred habitat types (peak, slope and valley) according to the spatial distribution of species and their habitat associations, and analysed the differentiations among their floral traits. We also divided 21 species into three clustering groups of floral traits, and had a comparison between the habitat types and the clustering groups. The results showed that species dominance had a significantly negative correlation with flower size and flower color vividness, which indicated that it should be a favored trait for trees to have small flower size or unattractive flower color in the community. Only the flower color lightness was significantly different among the three types, while other flower traits were not significantly different. However, there was weak consistency between the three types and the three main groups, with 57.14% species overlapped , which showed that habitats had something to do with flower traits differentiations. In conclusion, we believe that the floral traits are closely related to the dominance of species and habitats in the northern tropical karst forest. Moreover, floral traits might be more deeply affected by habitats than pollination in this region.