南亚热带常绿阔叶林树木多样性与生物量和生产力的关联及其影响因素

生物多样性和生态系统功能的关系直接或间接地影响着生产力, 是生态学研究的关键问题。本研究旨在定量探讨亚热带自然林演替后期森林生态系统树木多样性与生物量或生产力的关系。本研究基于中国南亚热带长期永久性样地的群落调查数据以及地形和土壤养分数据, 分析了南亚热带常绿阔叶林树木多样性与生物量和生产力的关联及其影响因素。相关性分析结果表明, 物种多样性与生物量呈显著负相关, 与生产力呈显著正相关; 结构多样性与生物量呈显著正相关, 与生产力呈显著负相关。此外, 不同环境因子对多样性、生物量和生产力的影响具有显著差异, 其中土壤含水量对生产力有显著影响, 物种多样性指标与部分地形和土壤因子均有相关性, 而群落结构多样性指标与土壤因子的相关性更强。方差分解结果表明, 结构多样性对生物量和生产力的单独效应的解释率最大, 分别为35.39%和5.21%; 其次是结构多样性和物种多样性的共同效应, 对生物量和生产力的解释率分别为13.66%和3.53%; 地形和土壤因子的解释率较小。同时, 结构方程结果也表明, 结构多样性对生物量有较强的直接正影响; 生物量对生产力有强烈的直接负影响, 结构多样性通过增加生物量明显地减少了生产力; 土壤和地形因子主要是通过物种和结构多样性间接影响生物量和生产力。综上, 本研究认为在南亚热带森林演替顶极群落中, 群落结构复杂性和物种多样性的提高对促进群落生产力和生物量具有重要作用。

Relationships between tree diversity and biomass/productivity and their influence factors in a lower subtropical evergreen broad-leaved forest

Aim The relationship between biodiversity and ecosystem function contribute to productivity, both directly and indirectly. Therefore, it is a critical issue of ecology. The aim of this study is to quantitatively explore the relationship between tree diversity and biomass or productivity of subtropical natural forest ecosystems in late successional stages. Methods Based on long-term community surveys of topographies and soil nutrients from permanent forest ecosystems in the subtropical evergreen broad-leaved forest, we analyzed the relationship between tree diversity and productivity/biomass and their influencing factors. In this analysis, the correlations between tree diversity and each factor were evaluated using a Pearson correlation analysis. The single and shared effects of each factor were quantified by variance partitioning analysis (VPA). In addition, the relationships between soil nutrients and topographies and their effects on productivity and biomass were further evaluated, either directly or indirectly, through species and structural diversity by using a structural equation model (SEM). Result Species diversity displayed a negative correlation with biomass and a positive correlation with productivity. Contrarily, structural diversity was positively correlated with biomass and negatively correlated with productivity. The effects of environment factors on tree diversity and biomass/productivity were varied. Specifically, soil moisture had a significant effect on productivity, species diversity was correlated with soil nutrients and topographies, and structural diversity was strongly related to soil nutrients. The variance partitioning analysis results indicated that the single effect of structural diversity explained the largest portion of variance in biomass (35.39%) and productivity (5.21%), followed by the shared effect of structural and species diversity on biomass (13.66%) and productivity (3.53%). Soil nutrients and topographies explained less variation in productivity and biomass. The structural equation results analysis indicated that structural diversity had a direct positive effect on biomass, and biomass had a strong direct negative effect on productivity. Structural diversity indirectly reduced productivity by increasing biomass. Soil nutrients and topographies were mainly affected by biomass, while productivity indirectly affected tree species and structural diversity. Conclusions These results indicate that (1) species diversity had the greatest direct effect on productivity, and structural diversity had the greatest direct effect on biomass in southern subtropical evergreen broad-leaved forests; (2) species diversity explained productivity better than structural diversity, while structural diversity explained biomass accumulation better than species diversity; and (3) both species diversity and structural diversity can be affected by soil nutrients and topographies.