DISSERTATION RESEARCH: Plant response to water availability and drought in a changing world

在过去60年里，全世界干旱的频率和严重程度都在增加，而且预计在今后几十年中还会继续增加。极端干旱事件已经对世界各地的树木和其他木本植物造成了损失，导致森林普遍死亡。随着温室气体排放在全球范围内持续上升，森林的重要性也在增加，因为树木可以吸收二氧化碳并以木材的形式储存数百年。然而，在干旱期间树木的死亡减少了可以吸收的二氧化碳量，并增加了死树分解时释放回空气中的二氧化碳量。 这个博士论文改进补助金将提供资金，以评估哪种植物更容易受到干旱的影响，以及决定植物的机制？对极端干旱事件的脆弱性。这项研究有可能揭示使木本植物或多或少耐旱的特征，并可能提高预测物种的能力。应对极端干旱事件。研究结果将使当地土地管理者和决策者了解哪些树种更耐旱，从而改进在干旱日益严重的情况下恢复和管理森林的计划。该项目将使用新的方法，利用植物解剖特征和生理测量来确定木本植物对极端干旱的抗性。干旱导致树木死亡的主要原因是植物导水管中的栓塞积聚，阻碍了水分从土壤向叶片的正常流动。研究人员将研究哪些解剖特征使植物更容易受到栓塞的影响。这项工作将在干燥和潮湿的温带和热带森林中进行，以提供关于在不同降雨环境下生长的植物如何应对干旱的信息。该项目将包括与哥斯达黎加农村地区的公立小学教师举办讲习班，该地区有着极端干旱的历史，导致森林大面积死亡。这些讲习班将通过积极学习植物如何获得和利用水以及干旱对原生森林的影响，加强哥斯达黎加小学课程。

Drought has been increasing in frequency and severity worldwide for the last 60 years, and the increase is expected to continue over the next several decades. Extreme drought events are already taking their toll on trees and other woody plants all over the world, leading to widespread forest mortality. As greenhouse gas emissions continue to rise on a global scale, the importance of forests increases, as trees can take up carbon dioxide and store it for centuries in the form of wood. However, the death of trees during drought reduces how much can be taken up and increases the amount of carbon dioxide released back into the air when dead trees decompose. This Doctoral Dissertation Improvement Grant will provide funds to evaluate which kinds of plants are more susceptible to drought, and the mechanisms that determine plants? vulnerability to extreme drought events. This research has the potential to reveal characteristics that make woody plants more or less tolerant to drought and may increase the ability to predict species? responses to extreme drought events. The results will inform local land managers and policy-makers on which tree species are more tolerant to drought and therefore improve plans for restoration and management of forests in the face of increasing drought severity. This project will use novel methods to determine the resistance of woody plants to extreme drought using plant anatomical features and physiological measurements. The major cause of tree mortality from drought is embolism accumulation in the water-conducting pipes of plants that obstruct proper water movement from the soil up to the leaves. The researchers will study which anatomical traits make plants more susceptible to embolisms. This work will be conducted in both dry and wet temperate and tropical forests to provide information on how plants growing under different rainfall environments respond to drought. The project will include workshops with public primary school teachers in rural Northwestern Costa Rica, which is an area with a history of extreme droughts that have resulted in widespread forest mortality. These workshops will enhance Costa Rican primary school curriculum through active learning of how plants obtain and use water and the impact of drought on native forests.