中国典型森林生态系统乔木层群落物种多样性的空间分布格局及其影响因素

物种多样性地理分布格局及其成因是生物地理学和宏观生态学研究的核心问题之一,基于中国13个典型森林生态系统乔木层群落植物的调查数据,分析物种多样性随经纬度的变化规律,探讨物种多样性空间分布格局的影响因素。结果表明:(1) 13个典型森林生态系统的4个物种多样性指数均随经纬度上升而下降,其中物种丰富度变化更为显著,而Shannon-Wiener指数、Simpson指数和Pielou指数随经度上升变化不显著;(2)相关性分析结果显示,物种多样性指数与植物特性、能量和水分因子的单因素相关关系并不一致。其中,物种丰富度、Shannon-Wiener指数和Simpson指数与年均温、最冷月均温、温度年较差和潜在蒸散量的相关性最显著(P0.01),Pielou指数与年均温、最冷月均温、实际蒸散量、潜在蒸散量和郁闭度有显著相关关系(P0.05);(3)方差分解结果表明,能量和水分的共同作用对物种多样性指数空间分布格局的解释率最高,达到15%—42%;植物特性、能量和水分因子三者共同作用对物种多样性指数空间分布格局解释率次之,为14%—27%;植物特性与能量因子或水分因子两者之间的共同作用以及植物特性和水分因子独立作用对物种多样性指数空间分布格局的解释率较小,其中能量因子对物种多样性指数空间分布格局的单独解释率高于植物特性或水分因子。研究表明能量和水分共同作用是影响大尺度森林乔木层物种多样性空间分布格局形成的主要因素,但植物特性的差异对物种多样性空间分布格局影响也不可忽视。

Biogeographic patterns and influencing factors of the species diversity of tree layer community in typical forest ecosystems in China

Large-scale patterns of species diversity are one of the most important and attractive issues of ecology and biogeography. Using the investigation data of tree layers in 13 typical forest ecosystems in China, we explored the geographical patterns and main influencing factors of species diversity in the forest community. Our results indicated that four species diversity indices decreased with an increase in latitude and longitude in the 13 typical forest ecosystems. Species richness, in particular, showed a significant variation along both latitude and longitude gradients, while the other indices showed a significant change only with an increase in latitude. A regression analysis showed that the species diversity indices were not consistent in correlation with a single factor, i.e., plant traits, energy, and moisture factor. The indices such as, species richness, Shannon-Wiener index, and Simpson index, showed the most remarkable correlation with the annual average temperature, coldest month average temperature, annual temperature difference, and potential evapotranspiration (P < 0.01). The Pielou index showed a significant correlation with the annual mean temperature, mean temperature of the coldest month, actual evapotranspiration, potential evapotranspiration, and crown density (P < 0.05). A variation partitioning analysis demonstrated that the synergy of energy and moisture had the highest explanation rate for the spatial distribution of species diversity index, reaching 15%-42%, and the interactions among plant traits, energy, and moisture factors had a secondary effect on the geographic distribution patterns of species diversity, with an explanation rate of 14%-27%. Furthermore, the shared effects of the other combinations of plant traits and energy factors were insignificant. The effect of energy factors on the distribution of species diversity indices was higher than the effect of plant traits or moisture in determining the species diversity in 13 typical forest ecosystems. Our results revealed that the shared effects of energy and moisture were the most crucial factors impacting the development of large-scale species diversity in the studied forest tree layer. Meanwhile, the effects of plant traits should not be ignored.