Collaborative Research: Conifer leaf anatomy determines hydraulic functioning

针叶树在生态和经济上都具有全球重要性。由于干旱、火灾和昆虫爆发，许多针叶树物种最近经历了极端的死亡事件。迫切需要了解针叶树的生理学，特别是针叶树针叶-负责碳吸收和水分流失调节的器官。针叶树的叶片解剖学和生理学之间存在着一个有趣的悖论：有着如此简单的单脉维管系统，它们如何与阔叶树种竞争或栖息在极端环境中？该项目旨在了解针叶树叶片解剖结构如何影响水分运输和光合作用，以及干旱期间针叶水分运输如何下降。这些信息将用于开发一个机械模型，以帮助预测森林生产力和死亡率，以应对干旱和其他环境挑战。该项目将为一名博士后研究员、一名研究生和多名本科生提供培训。此外，与麦考尔户外科学学校合作，五年级和六年级的学生，他们的父母和老师将参加一个名为“叶子里面发生了什么？“为了说明细胞水平的修改如何影响景观过程，将使用X射线成像生成的3D打印针叶树针叶模型。解剖模型将通过一个网站免费提供，供教师和学生在学校3D打印手持模型，或作为学校的教学工具包，而无需使用3D打印技术。针叶树栖息在一些最干燥和最寒冷的栖息地，那里有树木。许多针叶树物种受到热浪和干旱的威胁，这些热浪和干旱会引起生理压力，使它们更容易受到害虫和病原体的侵害。虽然大多数针叶树的叶子只有一个单一的静脉供应水的叶子，静脉外的内部解剖结构是令人难以置信的多样化整个针叶树的发育。这种多样性对水运输和碳吸收的影响尚不清楚。本研究的主要目的是建立一个机制框架，以了解针叶树叶片解剖结构对叶片导水率和光合能力的影响。这种机械的理解将被用来阐明针叶树如何适应干旱和寒冷的环境，也能够成功地与被子植物物种在进化历史上的竞争。该项目将把联合收割机最先进的三维成像方法（高分辨率X射线计算机微断层摄影术）与水力模型和叶片水力传导率的测量相结合，以澄清针叶树叶片内部解剖结构对水力功能的影响。

Conifers are globally important, both ecologically and economically. Many conifer species have recently experienced extreme mortality events due to drought, fire and insect outbreaks. There is an urgent need to understand conifer physiology, and especially conifer needles - the organs responsible for carbon uptake and regulation of water loss. Conifers have an intriguing paradox in the link between their leaf anatomy and physiology: with such a simplistic, single-vein vascular system, how can they compete with broadleaf species or inhabit extreme environments? This project aims to understand how conifer leaf anatomy influences water transport and photosynthesis, and how needle water transport declines during drought. This information will then be used to develop a mechanistic model to help predict forest productivity and mortality in response to drought and other environmental challenges. The project will provide training for a postdoctoral researcher, a graduate student, and multiple undergraduate students. Also, in collaboration with the McCall Outdoor Science School, 5th and 6th grade students, their parents and teachers will participate in a workshop called "What happens inside a leaf?" To illustrate how cellular-level modifications can influence landscape processes, 3D-printed conifer needle models generated from X-ray imaging will be used. Anatomical models will be freely available through a website for teachers and students to 3D print hand-held models at schools, or as teaching kits for schools without access to 3D printing technology. Conifers inhabit some of the driest and coldest habitats where trees are found. Many conifer species are threatened by heat waves and droughts that induce physiological stress that can make them more vulnerable to pests and pathogens. Although most conifer leaves have only a single vein supplying water to the leaf, the internal anatomy outside the vein is incredibly diverse across the conifer phylogeny. The impact of this diversity on water transport and carbon uptake is unknown. The primary goal of this project is to develop a mechanistic framework to understand the influence of conifer leaf anatomy on leaf hydraulic conductance and photosynthetic capacity. This mechanistic understanding will be used to illuminate how conifers have adapted to arid and cold environments and have also been able to successfully compete with angiosperm species over evolutionary history. The project will combine state-of the art 3-dimensional imaging methods (high-resolution X-ray computed micro-tomography) with a hydraulic model and measurement of leaf hydraulic conductance to clarify the impact of conifer leaf internal anatomy on hydraulic function.