Upgraded gas exchange system to support research in plant ecology

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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.