基于树形结构的木棉叶功能性状差异性研究

叶功能性状不仅反应植物对资源的利用能力，还涉及植物对自身结构和环境的生存适应策略。以不同生长阶段的木棉为研究对象，于2019年12月实地测量树高、冠幅等5个主要树形因子和采样测定叶面积、比叶面积、叶干物质含量、叶片含水量等14个叶功能性状，分析其在不同生长阶段的变化规律和相互关系，探讨叶功能性状对树形结构的响应。结果表明：不同生长阶段的木棉叶功能性状之间存在差异（P<0.05），且表现出一定的相关性（P<0.05，P<0.01）；木棉叶片的面积、长度、宽度、周长、鲜重、饱和重、干重、比叶质量和干物质含量等功能性状是随生长阶段变化的主要指标。影响木棉叶片各性状的树形因子也不相同，其中叶面积主要受到冠幅的影响，叶片鲜重和饱和重主要受到枝下高的影响，叶片干重和相对含水量主要受到树高的影响，比叶面积、叶片含水量和干物质含量主要受到树高、尖削度的影响，比叶质量主要受到胸径、尖削度、树高的影响。随着木棉的生长，叶功能性状表现出受树形结构的影响而具有较强的表型可塑性，有利于其适应内外环境的变化。因此，叶功能性状之间的变化差异和相关组合，反映了不同生长阶段的木棉对树形结构的适应性调整和对资源的利用策略，在一定程度上为探索西双版纳热带雨林区的生态保护和可持续发展提供相关科学依据。

Variation in leaf functional traits of Bombax ceiba Linnaeus communities based on tree structure

The leaf functional traits of plants not only reflect their abilities to use resources, but also represent their adaptation strategies to structural and environmental changes. Therefore, leaf functional traits are critical indicators of biogeochemical coupling in terrestrial ecosystems. In the present study, Bombax ceiba Linnaeus at different growth stages was taken as the main research subject, five main tree shape factors (i.e., height and crown breadth) were measured, and 14 leaf functional traits were quantified, including leaf area, specific leaf area, leaf dry matter content and leaf water content. We conducted the research in Menglun Town, Mengla County, Xishuangbanna Autonomous Prefecture in December 2019. We analyzed the changing patterns and mutual relations at different growth stages, and explored the responses of leaf functional traits to tree structure based on a variety of statistical analysis methods (i.e., One-way analysis of variance and multiple linear stepwise regression analysis). The results showed that leaf functional traits of Bombax ceiba Linnaeus differed in different growth periods (from primary growth stage to tertiary growth stage)(P<0.05), although they were also correlated certainly (P<0.05,P<0.01). Principal component analysis showed that leaf area, leaf length, leaf width, leaf perimeter, leaf fresh weight, leaf saturated weight, leaf dry weight, leaf mass per area, and leaf dry matter content were the main indicators with the increasing growth stage. The pattern of leaf functional traits was affected by various tree factors, which formed the best functional combination through the functional coordination among multiple characters so that plants could well adapt to environmental changes. We found that leaf area was mainly affected by the crown breadth. The leaf fresh weight and leaf saturated weight were mainly affected by the height to crown base. The leaf dry weight and leaf relative water content were mainly affected by the height, specific leaf area, leaf water content and leaf dry matter content were mainly affected by the height and taperingness, and leaf mass per area was mainly affected by the diameter, taperingness and height. With the growth of Bombax ceiba Linnaeus, the leaf functional traits showed strongly phenotypic plasticity influenced by tree structure, which was helpful to adapt to the changes in internal and external environment. Therefore, the variation and related combinations of leaf functional traits at different periods reflect the adaptability of Bombax ceiba Linnaeus to the tree structure and resource utilization strategies, which to a certain extent also provide relevant scientific basis for the exploration of the ecological protection and sustainable development of the tropical rain forest in Xishuangbanna.