PARENT SESSION
Oral Session #4: Plant Ecology: Gas Exchange. Presiding: J. Pereira.
Monday, August 6, 2001. 8:00 AM to 12:00 PM. Hall of Ideas P&Q.

Acclimation of plant respiration along an altitudinal gradient.

McCutchan, Cheryl¹, Monson, Russell², ^{1 2}

ABSTRACT- Evidence from laboratory-grown plants suggests that long-term thermal acclimation of respiration is distinctly different from the instantaneous temperature response of respiration. This fact is particularly important as attempts are made to model plant, ecosystem, and global carbon balance in response to changing climate. In this study, the respiration rates of two herbaceous perennials, Bistorta bistortoides and Campanula rotundifolia, were measured over a natural temperature gradient in the Rocky Mountains, USA. Respiration rate was measured at 15 and 25 °C throughout the growing season in the leaves, stems, and reproductive structures of the two species. In B. bistortoides, tissues from high altitude sites had higher rates of respiration than tissues from lower sites. The Q₁₀ of respiration also increased with altitude in B. bistortoides tissues. None of the C. rotundifolia tissues displayed a consistent increase in respiration rate with altitude although higher respiration rates were found in high altitude leaves than in leaves from lower sites. The Q₁₀ of respiration rate decreased significantly with elevation in all C. rotundifolia tissues. In the two species, acclimation of respiration rate to altitude is species dependent and involves changes in both the rate of respiration at a single temperature and the temperature sensitivity of respiration (Q₁₀).

KEY WORDS: respiration, temperature, acclimation, Q₁₀