已经提出了许多假设来解释海拔物种丰富度模式;然而,评估它们的重要性仍然是一个挑战,因为嵌套在不同生物地理区域的山脉具有不同的环境属性。这里,我们对树木进行了比较研究,灌木,草药,和蕨类植物沿着全球22座山脉的相同海拔梯度,检查能量假设的表现,容忍度,气候变异,和空间面积来解释每个植物组的海拔物种丰富度模式。结果表明,对于树木和灌木,与能量相关的因素比其他因素表现出更大的解释力,而与气候变化相关的因素在解释草本植物和蕨类植物的海拔物种丰富度模式方面表现更好。对于寒冷的山脉,能量相关因素成为木本物种多样性的主要驱动因素,而在更热和更湿润的生态系统中,温度和降水是沿海拔梯度的物种丰富度的最重要预测因子。对于草药和蕨类植物,物种丰富度的变化小于木本物种。这些发现为解释植物的海拔物种丰富度模式提供了有关能量理论普遍性的重要证据。强调潜在的机制可能会在不同的生长形式群体和山脉嵌套的区域之间发生变化。
Many hypotheses have been proposed to explain elevational species richness patterns; however, evaluating their importance remains a challenge, as mountains that are nested within different biogeographic regions have different environmental attributes. Here, we conducted a comparative study for trees, shrubs, herbs, and ferns along the same elevational gradient for 22 mountains worldwide, examining the performance of hypotheses of energy, tolerance, climatic variability, and spatial area to explain the elevational species richness patterns for each plant group. Results show that for trees and shrubs, energy-related factors exhibit greater explanatory power than other factors, whereas the factors that are associated with climatic variability performed better in explaining the elevational species richness patterns of herbs and ferns. For colder mountains, energy-related factors emerged as the main drivers of woody species diversity, whereas in hotter and wetter ecosystems, temperature and precipitation were the most important predictors of species richness along elevational gradients. For herbs and ferns, the variation in species richness was less than that of woody species. These findings provide important evidence concerning the generality of the energy theory for explaining the elevational species richness pattern of plants, highlighting that the underlying mechanisms may change among different growth form groups and regions within which mountains are nested.