Role of carbon reserves in tree and forest mortality

碳储量对树木和森林死亡率的作用

• 批准号: RGPIN-2016-04686
• 负责人: Landhäusser, Simon
• 金额: $ 3.79万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=615241
• 关键词: Role; carbon; reserves; tree; forest

Forest die-off is predicted to become more frequent with climate change. Our ability to predict these events is poor because we lack knowledge about the underlying physiological mechanisms of tree mortality. Specifically, nonstructural carbohydrate carbon reserves (sugars and starch) are involved in almost all critical physiological processes in plants, yet it remains hotly debated what role these carbon reserves play in the survival and mortality of trees. My long-term research objective is to understand the underlying processes controlling forest dynamics and forest ecosystem development. With the proposed research program I will test the overarching hypothesis that during times of stress, when carbon assimilation (photosynthesis) is limited, shifts in reserve allocation could lead to low carbon reserves in specific tissues or organs which in turn will play a critical role in the performance and potentially in the mortality of trees. Over the next five years, I will train 3 PhD and 2 M.Sc. students, as well as several undergraduates to investigate the following hypotheses in carbon reserve allocation of plants: 1. Carbohydrate allocation is a top-down process (e.g. sinks requiring carbon reserves closes to the source (leaves) will receive their reserves first). 2. Forest decline in tall trees is a consequence of top-down allocation, where roots will be affected negatively first (starved) by reduced carbon supply from the crown. 3. Stored reserves can be remobilized from storage tissues, but it is controlled by the distance of the storage source such that a) stores closest to location of need are remobilized first, and b) stored carbon in one organ is largely unavailable to other organs. This program will also be linked to a larger international effort to build a global meta-data set that will enable us to explore what the role functional tree traits, including carbon reserves, play in their growth and survival across a wide range of forest types and climates. My program will combine field and controlled greenhouse studies with mature and juvenile trees using state-of-the-art analytical equipment and protocols. The results will be a unique characterization of the importance of carbon reserves in trees which will fundamentally advance our understanding of the mechanisms and strategies involved in the storage of carbon reserves and their importance in stress tolerance in long-lived plants. Overall, this research program will establish the foundational scientific knowledge required to improve upon the prediction of forest mortality in response to a changing climate for Canadian forests and beyond.

据预测，随着气候变化，森林死亡将变得更加频繁。我们预测这些事件的能力很差，因为我们缺乏关于树木死亡的潜在生理机制的知识。具体而言，非结构性碳水化合物碳储备（糖和淀粉）参与了植物几乎所有的关键生理过程，但这些碳储备在树木的生存和死亡中发挥了什么作用仍然存在激烈的争论。 我的长期研究目标是了解控制森林动态和森林生态系统发展的基本过程。通过拟议的研究计划，我将测试总体假设，即在压力期间，当碳同化（光合作用）受到限制时，储备分配的变化可能导致特定组织或器官中的低碳储备，这反过来又将在树木的性能和潜在的死亡率中发挥关键作用。在接下来的五年里，我将培养3名博士生和2名硕士生，以及几名本科生，研究植物碳储量分配的以下假设： 1.碳水化合物分配是一个自上而下的过程（例如，需要碳储量的汇靠近源（叶）将首先获得其储量）。 2.高大树木的森林衰退是自上而下分配的结果，其中根部将首先受到树冠碳供应减少的负面影响（饥饿）。 3.储存的储备可以从储存组织中重新动员，但它受储存源的距离控制，使得a）最接近需要位置的储存首先被重新动员，并且B）一个器官中储存的碳在很大程度上不能被其他器官利用。 该计划还将与一项更大的国际努力相联系，以建立一个全球元数据集，使我们能够探索功能性树木特征（包括碳储量）在各种森林类型和气候中的生长和生存中所起的作用。我的计划将结合联合收割机领域和控制温室研究与成熟和幼龄树木使用国家的最先进的分析设备和协议。结果将是树木碳储量重要性的独特表征，这将从根本上促进我们对碳储量储存机制和策略及其在长寿植物抗逆性中的重要性的理解。总的来说，这项研究计划将建立所需的基础科学知识，以提高对森林死亡率的预测，以应对加拿大森林及其他地区不断变化的气候。