时空生态位互补性对亚热带森林生产力的影响

It has been widely accepted that biodiversity has a positive effect on productivity, however, the underling mechanisms have relatively seldom been verified, especially in forest communities. The complementary effect learned by previous studies mainly focused on neighbor interactions, but neglected the effect of composition turnover along environmental gradients on productivity. This project aims to fill this gap and also to test temporal complementarity among species by measuring water and light availability variations among seasons and the differential response of species to this environmental variation. We also plan to plant seedlings under manipulated light and water levels to explore their joint effect on both pioneer and shade-tolerant species. We are going to quantify the effect of light gradient partitioning on community productivity by comparing productivity of real and modeled communities. This project will improve our understanding on how biodiversity affects ecosystem productivity and offer key insights for promoting the quality of artificial forests.

目前生物多样性与群落生产力间的正向关系已被广泛接受，然而对多样性促进生产力的发生机制还鲜有验证，尤其在森林生态系统中开展的工作尤为匮乏。现有的机制性研究主要关注邻体间的相互作用，而未涉及物种组成的空间变化对生产力的影响。本项目拟以广东省黑石顶50公顷森林大样地平台为基础，借助已有的丰富本底数据，通过监测环境条件的季节变化和空间变异及其对不同树种生长和光合指标的影响，结合室内光照水分梯度控制试验，旨在从树种间时空生态位的互补性研究生物多样性促进生产力的发生机制这一关键科学问题。通过与零模型的群落生产力进行比较来量化光梯度分割对生产力的贡献度。本项目将为多样性保护和提高人工林质量提供机理依据。

本项目以探索生物多样性对亚热带森林生产力的影响机制为目的，开展了野外调查和温室实验。调查了黑石顶50公顷森林样地的光照空间分布，结合大样地丰富的本底数据，探讨了光分割对森林生产力的贡献；为研究光照、水分影响植物生长和存活的交互效应，在温室中设置了5个光照和5个浇水梯度，共25种处理，种植了6个树种的900盆幼苗进行生长指标测量并测量了21个叶性状、3个茎性状和17个根性状。通过温室实验证明，植物的生长速率或存活率与功能性状之间的相关性随环境（光照、水分）而改变。根据样地光照和物种分布，发现植物的耐阴性受其功能性状和土壤营养共同调节，同种植物个体耐阴性也随土壤营养而变化。基于这些结果，提出在研究植物的生长和存活的影响因素时，应考虑功能性状和环境的交互效应以及多种环境胁迫的交互效应。