COLLABORATIVE RESEARCH: Mechanisms for the decline of leaf hydraulic conductance with dehydration, and plant and environment level impacts

在这个项目中，将确定一个主要的植物反应的机制和后果，越来越多地认识到在细胞，组织和整个植物水平的过程中发挥核心作用-叶水运输（液压）系统的脆弱性脱水。 同样，叶水运输气孔控制和城市森林水平的蒸腾作用，城市用水的一个主要组成部分的影响，将得到澄清。 对于不同的城市树木在洛杉矶，该项目将联合收割机新的实验和纳米显微镜技术与建模相结合，以确定叶片水力传导（Kleaf）的机制，包括空气堵塞在叶脉，细胞崩溃，和膜蛋白（水通道蛋白）的活性变化的动态中的相对作用。 第二，该项目将研究Kleaf在确定气孔对大气干旱的反应方面的作用。 将开发一种新的水运输和气体交换系统的计算机模拟模型，并利用实验和解剖分析的数据进行参数化。 该模型可预测蒸腾或干旱条件下木质部解剖结构及其动态变化对气孔响应的影响。 该项目将根据城市树木气体交换反应的实验测量结果来测试和改进这个模型。 第三个目标是结合联合收割机的测量和模型与其他功能性状的数据来预测树木的水分利用和水分利用效率，并测试这些预测与树干液流和城市树木的生长测量。 总的来说，这项研究将在阐明植物水分运输的动力学和改善城市森林用水预测方面开辟新的科学领域，特别是对水资源保护至关重要。 更广泛的教育影响包括在研究中代表性不足的本科生的指导计划中进行协作数据收集，以提高对城市生态生理学和生态学的参与和欣赏。

In this project,the mechanisms and consequences of a major plant response will be determined that is increasingly recognized to play a central role in processes at cell, tissue and whole-plant level - the vulnerability of the leaf water transport (hydraulic) system to dehydration. Equally, the implications of leaf water transport for stomatal control and urban forest-level transpiration, a major component of city water use, will be clarified. For diverse urban trees in Los Angeles, the project will combine new experimental and nano-microscopy techniques with modeling to determine the relative roles in the dynamics of leaf hydraulic conductance (Kleaf) of mechanisms including air blockage within the leaf veins, cell collapse, and changes in the activity of membrane proteins (aquaporins). Second, the project will study the role of Kleaf in the determination of the stomatal response to atmospheric drought. A novel computer simulation model of the water transport and gas exchange systems will be developed, to be parameterized with data from experiments and from anatomical analyses. This model will predict the effect of xylem anatomy and its dynamics during transpiration or drought on the responses of stomata. The project will test and refine this model against experimental measurements of gas exchange responses for the urban trees. The third objective is to combine the measurements and model with additional functional trait data to predict tree water use and water use efficiency, and to test these predictions with sapflow and growth measurements for urban trees. Overall,this research will break new scientific ground in clarifying the dynamics of plant water transport, and improving prediction of urban forest water use, especially critical for conservation of water resources. The broader educational impacts include collaborative data collection within a mentoring program for under-represented undergraduates in research, to improve participation and appreciation of urban ecophysiology and ecology.