摘要
物种丰富度和种域(即物种分布范围)沿环境梯度的变化是生物地理学和生物多样性研究的核心问题。岛屿由于受到地理隔离的作用,其物种分布、多样性格局及其成因的特殊性对于发展和检验生物地理学的假说具有重要意义。Rapoport法则提出,生物种域存在着随海拔上升而增大的趋势。台湾地区具有显著的海拔梯度和典型的岛屿环境,其植物区系丰富而独特。我们首次对台湾维管束植物的海拔分布进行研究,包括不同类群植物的物种丰富度和种域的海拔梯度格局,并检验了Rapoport法则的适用性。综合相关信息得到台湾维管束植物区系包含241科1,466属4,751种(含种下单位),对其中具有海拔分布范围信息的3,330种植物进行统计,结果表明:(1)台湾维管束植物科、属、种的丰富度总体上随海拔上升而减小,入侵植物丰富度具有类似格局,而台湾特有植物呈现明显的单峰格局;按照分类群计,蕨类植物和裸子植物为单峰格局,被子植物的3个生态类群均为单调递减格局。(2)物种种域海拔宽度与海拔的关系随不同类群和分析方法而异。其中,入侵植物的种域宽度和中点海拔具有显著的正相关关系,支持Rapoport法则,而全部植物和特有植物不支持;蕨类植物的海拔分布支持Rapoport法则,裸子植物不支持,其他分类群因方法不同而结果之间不一致。我们还比较了台湾和周边大陆和岛屿山地的物种丰富度海拔格局,认为它们物种丰富度海拔梯度模式的不同可能与降水海拔格局的差异有关;而关于Rapoport法则的检验表明,即使在同一山体,不同类群植物分布范围的海拔模式也可能取决于不同的因素和作用机制。
Spatial patterns of species richness and range size along environmental gradients have long been central issues to biogeography and biodiversity. Because of their unique isolation effects on species distributions, much emphasis has been put on insular environments in developing and testing biogeography theories. Rapoport’s rule suggested an increasing trend of species range width along with increasing altitude. Taiwan, the largest island in China, is characterized by a significant altitudinal gradient, subtropical monsoon climate, as well as a rich and unique flora. Here, we offer the first report on the altitudinal patterns of species richness and species range size of Taiwan’s vascular plants, and analyze the relationship between altitudinal range size and range midpoint to test Rapoport’s rule. We established a database of 4,751 plant species (including subspecies levels), belonging to 241 families and 1,466 genera. Among these, 3,330 species have altitudinal range records and were analyzed. Taxonomic richness at the family, genus and species levels decreased with increasing elevation in terms of all plants and invasive species, and a hump-shaped altitudinal pattern of species richness was found for endemic plants. With regard to taxonomic groups, pteridophytes and gymnosperms richness exhibited hump-shaped patterns, while decreasing richness with increasing altitude was found for three subgroups in angiosperm (i.e. herbs, evergreen and deciduous woody plants). Relationships between species range size and midpoint elevation varied among assemblages as well as among methods applied to the same assemblage. The distribution of invasive plants supported Rapoport’s rule, while that of endemic species and overall species did not. The distribution of pteridophytes supported Rapoport’s rule, while gymnosperms did not. For angiosperms, no consistent patterns were found when different methods were applied. By comparing Taiwan and adjacent large insular and continental mountains, we suggest that the altitudinal patterns of precipitation might contribute to that of species richness. Our test of Rapoport’s rule suggested that, even on the same mountain, altitudinal variation of distributional patterns among different assemblages can result from different mechanisms.
出处
《生物多样性》
CAS
CSCD
北大核心
2010年第3期312-322,共11页
Biodiversity Science
基金
国家自然科学基金重点项目(40638039)