Effects of Atmospheric CO 2 Enrichment on Net Photosynthesis and Dark Respiration Rates of Three Australian Tree Species

Abstract

Summary Net photosynthesis and dark respiration rates of leaves of three Australian tree species exposed to a range of atmospheric CO2 concentrations were measured throughout the summer of 1991. For all three species — the Australian bottle tree (Brachychiton populneum (Schott.) R. Br.) and two eucalyptus (Eucalyptus microtheca F. Muell. and E. polyanthemus Schauer) — dark respiration dropped by approximately 50% for a 360 to 720 µL/L doubling of the air's CO2 concentration, while net photosynthesis rose by a factor of two. These results were not significantly different from results obtained previously for the common sour orange tree (Citrus aurantium L.).