Upgraded gas exchange system to support research in plant ecology

我们正在申请资金，以升级和加强现有的Li-COR气体交换系统(Li-6400型)的能力，该系统最初是在2003年使用CFI资金购买的。在过去的7年里，该仪器支持了育空地区的几个实地项目，其他研究实验室和学生对该仪器的需求很高。升级而不是更换这些设备将节省大约40 000美元的费用。收购几个新的叶测量室将极大地扩展其支持各种研究项目的能力，并为HQP提供新的培训机会。我们的计划允许通过协调和互补使用在两所大学的四个研究小组之间共享这些升级和新的设备。这种设备和可能的新观测将有助于为更好地了解植物和北方生态系统在不断变化的气候中的生理反应奠定基础。对叶片气体交换和荧光的联合测量将提供关于不同环境条件下光合作用过程的基本信息，包括极端条件的影响，如常青树的冬季冻融事件和草原物种的夏季干旱。例如，在亚北极山区，寒冷诱导的光抑制似乎限制了高山向南坡上白云杉的生长，而向北坡上的生长则受到较低土壤温度的限制。能够测量气体交换过程中的差异也是回答有关物种之间竞争的问题的核心。最后，通过在田间和温室研究中结合光学和气体交换测量来评估光合作用下调，我们将有助于开发新的方法来测量植物对环境变化和变化的反应。

We are requesting funds to upgrade and enhance the capability of an existing LI-COR gas exchange system (model LI-6400) that was originally purchased in 2003 using CFI funds. This instrument has supported several field-based projects in the Yukon over the past 7 years, and is in high demand by other research labs and students. Upgrading, rather than replacing, this equipment would result in an approximate $40,000 cost savings. The acquisition of several new leaf measurement chambers will greatly expand its capability to support a variety of research projects and provide new training opportunities for HQP's. Our plans allow for sharing this upgraded and new equipment across four research groups at two universities through coordinated and complementary use. This equipment and the new observations that are possible will help to lay the foundation for a better understanding of physiological responses of plants and northern ecosystems in a changing climate. Combined measurements of gas exchange and fluorescence at the leaf level will provide essential information about photosynthetic processes under different environmental conditions, including the effects of extreme conditions such as winter freeze-thaw events for evergreen trees and summer drought for grassland species. For example, in sub-Arctic mountains cold-induced photoinhibition appears to limit growth of white spruce at alpine treeline on south-facing slopes, while growth on north-facing slopes is limited by lower soil temperatures. Being able to measure differences in gas exchange processes are also central to answering questions about competition between species. Finally, by assessing photosynthetic downregulation through combined optical and gas exchange measurements in field and greenhouse studies, we will contribute to the development of new methodologies for measuring plant responses to environmental variability and change.