南亚热带森林群落物种分布格局研究：联结植物功能性状与水分生理过程的群落构建机制

In recent years, much progress has been made on community assembly mechanisms when inferred from plant functional traits. However, functional traits are only approximations of physiological processes, and even when patterns are identified, physiological mechanisms underlying community assembly may still be elusive. We have established a 20 ha forest biodiversity monitoring plot at Dinghushan National Nature Reserve. The plot is characterized as a lower subtropical evergreen broad-leaved forest. Seasonal and even abnormal drought frequently occur in this type of forests, suggesting that this forest has a high potential for studying the effects of functional traits and hydraulic physiology and their linkage on species distribution. In the proposed research, we will, for the first time, link plant functional traits and hydraulic physiology to infer community assembly mechanisms. Our research will be started with plant functional traits (plant morphology) and hydraulic measures (water transport capacity and drought tolerance), and will then be focused on how plant functional traits, hydraulic physiology and their linkage influence the distribution patterns of all 178 woody species with DBH≥1 cm within the plot. Because functional traits are only approximations of physiological processes, our research will also evaluate how well the functional trait approach predicts the actual physiological measurements. Based on the results of the proposed research, we expect to put forward the community assembly mechanisms in lower subtropical evergreen broad-leaved forests. Our research can provide theoretical foundations for biodiversity maintenance and species coexistence in subtropical forests, and can provide information to predict how species will respond to changes in global precipitation patterns. We also expect to make innovative contributions to understanding the relationship between plant functional traits and plant physiological processes.

以植物功能性状解释群落构建成因近年来取得重要进展，然而，功能性状仅仅是物种生理过程的近似，在解释群落构建的生理机制方面存在局限。南亚热带森林常遭受季节性干旱和异常性干旱，为研究功能性状和水分生理过程及其关联对群落物种分布格局的影响提供了极佳素材。本项目以鼎湖山南亚热带常绿阔叶林20 ha样地内胸径≥1 cm的全部178个乔木和灌木物种为研究对象，通过分析功能性状、水分生理过程及其关联与群落物种分布格局的关系，首次将功能性状（植物形态）与更深层次的水分生理过程（水分运输能力和耐旱性）联结起来，更全面解析南亚热带森林群落构建机制，并从水分生理过程角度评价功能性状预测实际生理过程的能力。研究结果可为南亚热带森林生物多样性的维持机制及物种共存理论提供重要的理论支持，为了解物种响应全球降雨格局变化提供重要参考，而且通过揭示功能性状预测实际生理过程的能力，为功能性状和生理过程关系研究作出创新性贡献。

项目以鼎湖山南亚热带常绿阔叶林20 ha样地内胸径≥1 cm的85个乔木和灌木物种为研究对象，通过分析功能性状、水分生理过程及其关联与群落物种分布格局的关系，首次将功能性状与水分生理过程（水分运输能力和耐旱性）联结起来，更全面解析了南亚热带森林群落构建机制，并从水分生理过程角度评价功能性状预测实际生理过程的能力。研究发现，植物功能性状和水分生理过程均能较好的表征物种分布格局。功能性状中植物叶片单位干重P含量和最大树高，其次是SLA和单位叶面积的净光合速率（Aarea）对物种分布格局预测能力最强；水分生理参数中，除了P50以外，水分运输能力（Ks和Kl）、HV及抗旱性（Tlp）均可预测植物物种在海拔和凹凸度水平的分布格局。通过多元逐步回归模型综合分析植物功能性状和水分生理过程共同作用对物种分布格局产生的影响，发现功能性状更能有效预测物种分布格局。水分生理特征中仅Tlp可预测物种沿海拔水平的分布，其它水平的分布格局大都与功能性状相关，特别是植物叶片单位干重P含量可预测树种在海拔和凹凸度水平的分布格局。最大树高可预测除了凹凸度和坡度以外的其它水平的物种分布格局。功能性状及水分生理过程对于坡度水平的物种分布格局均不能有效预测。研究结果可为南亚热带森林生物多样性的维持机制及物种共存理论提供重要的理论支持，为了解物种响应全球降雨格局变化提供重要参考。