DISSERTATION RESEARCH: The structure-function tradeoffs associated with embolism resistance in conifer wood

论文研究：与针叶树抗栓塞性相关的结构功能权衡

• 批准号: 0308862
• 负责人: John Sperry
• 金额: $ 1.27万
• 依托单位: University of Utah
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-06-01 至 2005-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0308862&HistoricalAwards=false
• 关键词: DISSERTATION; RESEARCH; structure; function; tradeoffs

Dissertation Research: The structure-function tradeoffs associated with embolism resistance in conifer woodJohn Sperry and Jarmila PittermannUniversity of UtahWater transport in plants may be challenged by drought and/or freezing. When subjected to either phenomenon, the introduction of air into the water conducting tissue (xylem) may impair the movement of water from root to stem by what is commonly referred to as embolism. What are the costs associated with resistance to embolism under these stresses? The current research will answer this question by investigating the hydraulic efficiency and wood anatomy of members of the Pinaceae, Cupressaceae and Podocarpaceae families. Conifers are the ideal choice for this study because the structural simplicity of their wood, coupled with their broad distribution will allow for effective modeling and testing of their hydraulic response to drought and freezing. Currently, it is known that large xylem conduits are efficient conductors of water, but highly vulnerable to freezing-induced embolism. Also, drought resistant xylem exhibits high wood density, and is costly to construct. Hence, hydraulic conductance and wood density represent the currency of the cost-benefit tradeoffs associated with freezing and drought resistance, respectively. The predictions are that conifers inhabiting regions prone to water deficit and freezing, such as North American high deserts, will be much less vulnerable to these stresses, but at the cost of reduced hydraulic efficiency, and high wood density. Conversely, taxa inhabiting warm, mesic regions where freezing is rare, as in Australian tropical rainforests, will exhibit low tolerance to drought and freezing stress, but will enjoy efficient hydraulic conductance. Ultimately, conifers inhabiting any point on the drought-freezing spectrum will optimize their cost-benefit strategy to maximize fitness in their habitat. The goals of this research are to clarify not only the physiological significance of variation in xylem anatomy, but also the selective forces restricting current and past conifer distributions.

论文研究：针叶林中与血栓抗性相关的结构-功能权衡约翰·斯佩里和贾米拉·皮特曼犹他州大学植物的水分运输可能会受到干旱和/或冰冻的挑战。当受到任何一种现象的影响时，空气进入导水组织(木质部)可能会损害水从根到茎的运动，这通常被称为栓塞症。在这些压力下，与抗栓有关的成本是多少？目前的研究将通过研究松科、柏科和罗汉松科植物的水力效率和木材解剖来回答这个问题。针叶树是这项研究的理想选择，因为它们木材的结构简单，加上它们广泛的分布，将允许对它们对干旱和冰冻的水力反应进行有效的建模和测试。目前，已知大木质部导管是水的有效导体，但极易受到冰冻诱导的血栓的影响。此外，抗旱的木质部表现出高的木材密度，而且建造成本很高。因此，水力传导性和木材密度分别代表了与抗冻和抗旱相关的成本-效益权衡。据预测，居住在易缺水和易结冰地区的针叶树，如北美高地沙漠，将不太容易受到这些压力的影响，但代价是水力效率降低和木材密度高。相反，生活在温暖的中原地区的类群，如澳大利亚的热带雨林，将表现出对干旱和冰冻胁迫的低耐受性，但将享受有效的水力传导性。最终，栖息在干旱-冰冻光谱上的任何点的针叶树都将优化它们的成本效益策略，以最大限度地适应它们的栖息地。本研究的目的不仅在于阐明木质部解剖变异的生理意义，还在于阐明制约当前和过去针叶树种分布的选择性因素。