物种丰富度垂直分布格局及影响机制

物种丰富度分布格局是一定地域内物种丰富度沿三维空间的立体分布,包括物种丰富度在经度、纬度和垂直梯度(海拔高度和海水深度)三个维度上的空间分异。近年来物种多样性的垂直分布格局与机制研究得到了生物地理学家和生态学家的重视。物种丰富度的垂直分布格局存在多种类型,但随海拔增加而物种数减少的单调递减模型和中海拔物种丰富度最高的单峰模型较为常见。目前在机制研究中验证较多的是气候稳定性、生物因子(种间相互作用)、能量、生境异质性、干扰、进化时间、物种分化速率、面积、中域效应(mid-domain effect)、生态位保守性(niche conservatism)等假说和机制。物种丰富度的分布格局是多方面因素综合作用的结果;由于地理、地形、气候、地质演化历史、物种库和进化历史、物种分化速率、干扰等差异,在不同地区存在着特别的物种丰富度空间分布格局和机制;处于同一地区的不同类群的物种也因进化扩散历史和生态适应能力不同而呈现多样化的分布格局。因此,对不同地区和类群的物种丰富度格局和机制进行研究应具体分析后才能得到可信结论。

Species Richness Patterns and Mechanisms along the Elevational Gradients

Species richness pattern is a stereo pattern that distributing within a certain land area, it includes three-dimensional distribution of species richness that occurring in longitude, latitude and vertical (elevation above sea level and depth under sea level) gradients. In recent years, species richness patterns and underlying mechanisms along the elevational gradient have been widely depicted by biogeography scientists and ecologists. Despite species richness patterns along the elevational gradient are very diverse; two universal patterns are widely reported: species richness decreases as the elevation increasing and species richness peaks at mid-elevations. Climate stability, biological factors (interspecies interaction), energy, habitat heterogeneity, disturbances, evolutionary time, speciation rate, area, mid-domain effect, niche conservatism are widely used in explaining the disparity of species richness patterns. One consensus among these related studies is that species richness pattern is driven by multiple factors and also the comprehensive interactions among driving factors. Species richness pattern differs among regions due to the unique and different geography, topography, climate, geological evolutionary history, species pool, species evolutionary history, speciation rate, disturbances and other factors. Therefore, the underlying mechanisms and the main driving factor of species richness patterns differ among regions. Even within a region, species richness pattern differs among different taxonomic species groups because the evolutionary and dispersal history as well as the ecological adaptability differ among species groups. Therefore, we need to carry out specific and careful analysis to gain reliable conclusion when explaining species richness patterns and underlying mechanisms among regions and species groups.