PARENT SESSION
Oral Session 10: Physiology I: Temperature, Light, and Growth.
Presiding: C Knight
Monday, August 2, 8:00 AM to 11:30 AM, Meeting Room C 123.

Acclimation of leaf respiration to temperature: Evidence across diverse sources of three deciduous tree species.

Lee, Tali^{*,1, 2}, Bolstad, Paul², Reich, Peter², ¹ University of Wisconsin - Eau Claire, Eau Claire, WI² University of Minnesota - Twin Cities, St. Paul, MN

ABSTRACT- Specific rates of plant cellular respiration are sensitive to prevailing temperature and are modulated by both genotypic adaptation and phenotypic acclimation. Evidence of adaptation and/or acclimation of respiration have been found for many species, however the relative influence of each is not well established for most species. The objective of this study was to evaluate the rapidity and magnitude of acclimation of respiration to temperature in field grown tree seedlings and to assess inter- and intraspecific variation in this response. We measured rates of leaf dark respiration and associated traits (total nonstructural carbohydrates, tissue nitrogen, and specific leaf area) on seedlings of Quercus alba, Q. rubra and Acer rubrum growing in a common-garden experiment in Minnesota (45° N, 93° W). Seedlings of each species were derived from at least three geographically diverse sources (between 31 and 47 °N) spanning a gradient of approximately 15°C mean annual temperature. Gas exchange measurements at a common temperature (24°C) were made during consecutive cool and warm weather systems across two growing seasons. We observed rapid, significant acclimation of leaf respiration to temperature. Specific rates of respiration declined linearly with increasing prior three-day temperature averages across all species. Across cool to warm (average 15 to 25°C) temperature events, mass-based rates of respiration decreased 56% for A. rubrum, 46% for Q. alba, and 39% for Q. rubra. Data also suggests a lower Q10 of leaf respiration following warm weather systems. In most analyses, sources within species did not differ. This acclimation response to temperature does not appear to be dependent upon changes in leaf N but rather is associated with adjustments in total nonstructural carbohydrates and specific leaf area. Models that incorporate short-term acclimation of respiration to temperature are needed to accurately predict forest responses to global change.

Key words: acclimation, eastern deciduous trees, leaf respiration, temperature