The Dynamics of Nonstructural Carbon in Perennial Plants

植物以非结构碳（NSC）的形式运输、积累和储存光合作用产物，主要以糖和淀粉的形式存在。 这些化合物为植物组织的生长和维持以及防御、繁殖和共生提供能量。 现有的研究表明，NSC在植物的竞争和生存能力的损害或压力中发挥作用。NSC也代表了一个工厂的年度碳预算的一个重要部分，有助于林分水平生产力的年际变化。 目前，植物中的NSC模型是概念性的，而不是定量的，因为我们不知道C在这些重要形式中存在多长时间。该项目将使用放射性碳来测量从干木材中提取的淀粉和糖的年龄，以及共存的万年青和落叶橡树（栎属L.）在加州。 选择橡树是因为它们的重要性，因为它们在相同的气候条件下有不同的生活策略，因为它们的恢复能力的限制将有助于决定它们在疾病和干旱压力下生存的能力。 据预测，NSC池在气候最不可预测的地方（即物种分布范围的极端）最古老，在气候变化最少的地方最年轻。 NSC在植物存活中的作用将通过研究植物受到干旱或落叶（食草动物）等胁迫时所呼吸的CO2的年龄来探讨。在即将到来的世纪，植物可能会因气候变化而面临更大的压力，食草动物、火灾或与入侵者的竞争也会增加。 NSC是植物科普逆境和伤害的主要机制。在这个项目中进行的测量将直接评估是否有长期的NSC商店可供植物使用，以及它们使用这些商店在不利条件下生存的程度。 更广泛的影响。该项目有很大的潜力，以提高我们对森林碳库和周转的理解。这对于理解植物对气候变化的反应和地球的总体碳预算非常重要。该项目将支持研究生和本科生的研究培训。本科生夏季研究经验项目的成员将参与并了解这项研究。PI每年提供一个关于放射性碳在生态学中的使用的夏季课程，这是该国唯一的一个此类课程。

Plants transport, accumulate, and store the products of photosynthesis as nonstructural carbon (NSC), mainly in form of sugars and starch. These compounds provide energy for growth and maintenance of plant tissues, as well as for defense, reproduction and symbiosis. Existing research indicates that NSC plays a role in a plant's ability to compete and survive damage or stress. NSC also represents a significant fraction of a plant's annual C budget, contributing to interannual variation in stand-level productivity. Currently, models of NSC in plants are conceptual rather than quantitative, because we do not know how long C resides in these important forms. This project will use radiocarbon to measure the ages of starch and sugars extracted from stem wood as well as stem-respired CO2 in co-existing evergreen and deciduous oak trees (genus Quercus L.) in California. Oaks were chosen for their importance, for their different life strategies in the same climate situation, and because limits to their resilience will help determine their ability to survive disease and drought stress. NSC pools are predicted to be oldest where climate is least predictable (i.e. at the extremes of the species' ranges), and youngest where climate varies least from one year to the next. The role of NSC in plant survival will be explored by studying the age of CO2 respired by plants subjected to stresses like drought or defoliation (herbivory). The coming century will likely see increases in the stresses to which plants are exposed through climate change and increases in herbivory, fire or competition with invaders. NSC provides a major mechanism for plants to cope with stress and damage. The measurements made in this project will directly assess whether there are longer-term NSC stores accessible to plants, and the degree to which they use these stores to survive adverse conditions. Broader impacts. The project has significant potential to increase our understanding of forest carbon pools and turnover. This is important in understanding plant response to climate change and in the earth's overall carbon budget. The project will support the training of graduate and undergraduate students in research. Members of a summer Research Experiences for Undergraduates program will participate and learn about the research. A summer course on the uses of radiocarbon in ecology that is the only one of its kind in the country is offered annually by the PI.