年际和季节功能性状变化对古田山常绿阔叶林物种共存影响的研究

Ecologists increasingly appreciate the importance of interspecific trait difference in community assembly. However, they have long ignored the effect of interannual and seasonal variation of functional traits on interspecific temporal niche differentiation in subtropical forest communities. This may lead to the underestimation of the contribution of interspecific temporal niche differentiation to species coexistence. The measurement of interannual and seasonal variation of functional traits in diverse subtropical forests is extremely labor-consuming and time-consuming. This makes it difficult or impossible to analyze the effect of interannual and seasonal variation of functional traits on temporal niche differentiation. However, based on comparison of reflectances at absorbing wavelengths from different biochemical components of leaves, hyperspectral imaging can be used to fast detect interannual and seasonal variation of functional traits. At the same time, LiDAR techniques can be used to monitor variation of morphological traits. In this study, we will try to combine ground survey and canopy crane-based LiDAR and hyperspectral imaging to monitor interannual and seasonal variation of functional traits such as leaf nitrogen and phosphorus content and morphological trait such as leaf area index (LAI). We then explore the effect of interannual and seasonal variation of key functional traits on tree growth and interspecific competition. We thus can determine the interspecific temporal niche differentiation. By comparing with other forces of community assembly such as spatial niche differentiation and negative density dependence, we can estimate the relative contribution of temporal niche differentiation to species coexistence in this subtropical evergreen broadleaved forest.

生态学家在认识到种间功能性状差异及其对群落构建重要作用的同时，却长期忽略了亚热带森林中功能性状的年际和季节动态变化对种间时间生态位分化的影响，从而可能低估计了时间生态位分化在物种共存中的贡献。研究亚热带森林多物种功能性状的年际和季节变化需要巨量的野外观测和室内测试，使这方面工作难以开展。利用叶片不同的生化组分对不同波段光谱的吸收特征，采用LiDAR和高光谱影像技术可便宜、快捷和准确地测量一些关键的叶生化和形态功能性状，使探索种间时间生态位分化成为可能。本项目试图结合地面监测和塔吊搭载的LiDAR和高光谱影像平台，监测亚热带常绿阔叶林物种叶生化和形态功能性状的年际和季节变化，探讨这些功能性状的年际和季节变化对树木生长和种间关系的影响，从而估计种间时间生态位分化，并与影响亚热带群落构建的其它机制如空间生态位分化、密度制约等相比较，阐明种间的时间生态位分化对古田山常绿阔叶林物种共存的相对贡献。

本项目结合地面监测和塔吊搭载的LiDAR和高光谱影像平台，监测亚热带常绿阔叶林物种叶生化和形态功能性状的年际和季节变化，探讨这些功能性状的年际和季节变化对树木生长和种间关系的影响。在本项目中，1）利用激光雷达技术发现，林冠结构复杂程度随森林的演替而增加，从而导致上层和下层林冠之间的不对称竞争，引起生产力的降低；2）古田山森林中，稀有种具有比常见种更狭窄的环境生态位，但功能生态位与常见种相似或更宽；3）森林群落沿纬度梯度具有显著的β多样性, 生态位专一性和生态位空间沿纬度梯度的变化是导致β多样性变化的主要机制；4）经过雪灾干扰后，幼苗存活率受到同种和异种大树邻居密度(生物变量）、系统发育关系（生物变量）以及环境变量（非生物变量）的共同影响；5）围绕生物多样性编目与监测、生物多样性机制与过程、生物多样性致危因素及其对全球变化的响应三个方面的十个主题，从全球视角出发综述了我国生物多样性研究进展。本项目有7篇研究论文发表，监测的时间序列数据正在进一步分析和发表中。