© 2000 Heron Publishing—Victoria, Canada
Direct effect of elevated CO2 on nocturnal in situ leaf respiration in nine temperate deciduous tree species is small
Jeffrey S. Amthor (1)
1. Environmental Sciences Division, Oak Ridge National Laboratory, Mail Stop 6422, PO Box 2008, Oak Ridge, TN 37831-6422, USA (AmthorJS@ORNL.gov) / Received March 18, 1999
Summary
Direct (i.e., short-term) effects of elevated CO2 on nocturnal in situ leaf respiration rate were measured in nine deciduous tree species (seven genera) in 20 3.5–4.0-h experiments. During the
experiments, CO2 concentration was alternated between 400 and 800 ppm (approximately 40 and 80 Pa of CO2). Data analysis accounted for effects on respiration rate of the normal decline in temperature with time after sunset. The
median response to a 40-Pa increase in CO2 was a 1.5% decrease in respiration rate, with responses ranging from a 5.6% inhibition to a 0.4% stimulation. Direct effects
of elevated CO2 on respiration were similar among the species. Thus, the response of nocturnal leaf respiration rate to a short-term CO2 increase was small, and of little practical importance to the accuracy of measurements of respiration involving similar changes
in CO2 concentration during measurement. These direct respiratory responses of leaves to elevated CO2 would translate into only slight, if any, effects on the carbon balance of temperate deciduous forests in a future atmosphere
containing as much as 80 Pa CO2.
Keywords:
Acer, atmospheric CO2 concentration, Cercis, CO2 efflux, Liquidambar, Liriodendron, nighttime respiration, Prunus, Quercus, Ulmus.
