Functional Convergence and Constraints in Regulation of Transpiration and Carbon Assimilation in Tropical Forest Canopy Trees

热带林冠树蒸腾和碳同化调节的功能收敛和约束

• 批准号: 9905012
• 负责人: Frederick Meinzer
• 金额: $ 27.4万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-07-01 至 2005-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9905012&HistoricalAwards=false
• 关键词: Functional; Convergence; Constraints; Regulation; Transpiration

Lowland tropical forests are notable for their high plant species diversity, particularly tree species. This project is based on the premise that despite the bewildering diversity of tree species in tropical forests, similar adaptive responses occur across a wide range of species. Constraints on the possible combinations of adaptive responses should lead to convergence among basic plant traits related to regulation of carbon assimilation and transpiration, two fundamental processes. Consistent with this, the PIs prior use of the Smithsonian Tropical Research Institute (STRI) canopy crane in Panama to make concurrent measurements of water use at multiple scales from single leaf to whole tree, has revealed a surprising degree of functional convergence in regulation of transpiration among diverse tree species.In the current project, the PIs are building upon the PIs previous observations to determine the extent to which leaf level regulation of transpiration and carbon assimilation are governed by tree architecture and size. The problem of characterizing plant behavior over an adequate range of scale has been particularly acute with large forest canopy trees. The advent of canopy cranes has revolutionized access to all parts of forest canopy trees from their trunks, to intermediate branches, to leaves in the upper crown. The PIs are therefore taking advantage of the unique opportunity provided by the STRI canopy cranes to study large trees as whole organisms. One of our key objectives is to identify appropriate numerical scaling factors that relate tree physiological behavior to tree architectural features such as the ratio of leaf area to sapwood area. These scaling factors will detect functional convergence in regulation of carbon uptake, and the uptake, transport and loss of water among diverse tree species. Development of scaling factors that reveal areas of functional convergence will provide new insights that will greatly simplify interpretation and modeling of tree, stand and ecosystem level responses in these complex, species-rich forests. Furthermore, demonstration that similar functional constraints apply across a wide range of species leading to trade-offs among basic plant traits related to structure and function may serve to move the science of ecology towards new paradigms concerning the nature of differences and similarities among plant species. The PIs expect approaches, results and general conclusions to be applicable to a wide range of natural and managed forests, not just tropical forests. The PIs also expect the results of this research to contribute to the ability to predict the consequences of different management practices for forest productivity and utilization of water resources.

热带低地森林以其丰富的植物物种多样性，特别是树种而闻名。该项目的前提是，尽管热带森林中树种的多样性令人眼花缭乱，但类似的适应性反应发生在广泛的物种中。对适应性响应可能组合的限制应导致与碳同化和蒸腾调节相关的基本植物性状趋同，这是两个基本过程。与此一致的是，PIs先前在巴拿马使用史密森尼热带研究所（STRI）的树冠起重机在从单叶到整棵树的多个尺度上同时测量水的利用，揭示了不同树种之间蒸腾调节的功能趋同程度令人惊讶。在目前的项目中，pi正在建立pi先前的观察结果，以确定叶片水平对蒸腾和碳同化的调节在多大程度上受树木结构和大小的支配。在适当的尺度范围内描述植物行为的问题对于大型森林冠层树木来说尤其尖锐。树冠鹤的出现彻底改变了进入森林树冠树的所有部分，从树干到中间的树枝，再到树冠上部的叶子。因此，pi利用STRI树冠起重机提供的独特机会，将大树作为整个生物进行研究。我们的主要目标之一是确定适当的数值缩放因子，将树木的生理行为与树木的建筑特征（如叶面积与边材面积的比例）联系起来。这些尺度因子将检测不同树种在碳吸收、吸收、运输和水分损失调节中的功能收敛性。揭示功能趋同区域的尺度因子的发展将提供新的见解，这将大大简化这些复杂的、物种丰富的森林中树木、林分和生态系统水平响应的解释和建模。此外，证明类似的功能约束适用于广泛的物种，导致与结构和功能相关的基本植物性状之间的权衡，可能有助于将生态学科学推向有关植物物种之间差异和相似性本质的新范式。指数期望方法、结果和一般结论适用于广泛的天然森林和管理森林，而不仅仅是热带森林。指数还期望这项研究的结果有助于预测不同管理做法对森林生产力和水资源利用的影响。