title: Growth and photosynthetic response of nine tropical species with long-term exposure to elevated carbon dioxide.
abstract: Seedlings of nine tropical species varying in growth and carbon metabolism were exposed to twice the current atmospheric level of CO2for a 3 month period on Barro Colorado Island, Panama. A doubling of the CO2concentration resulted in increases in photosynthesis and greater water use efficiency (WUE) for all species possessing C3metabolism, when compared to the ambient condition. No desensitization of photosynthesis to increased CO2was observed during the 3 month period. Significant increases in total plant dry weight were also noted for 4 out of the 5 C3species tested and in one CAM species, Aechmea magdalenae at high CO2. In contrast, no significant increases in either photosynthesis or total plant dry weight were noted for the C4grass, Paspallum conjugatum. Increases in the apparent quantum efficiency (AQE) for all C3species suggest that elevated CO2may increase photosynthetic rate relative to ambient CO2over a wide range of light conditions. The response of CO2assimilation to internal Cisuggested a reduction in either the RuBP and/or Pi regeneration limitation with long term exposure to elevated CO2. This experiment suggests that: (1) a global rise in CO2may have significant effects on photosynthesis and productivity in a wide variety of tropical species, and (2) increases in productivity and photosynthesis may be related to physiological adaptation(s) to increased CO2.
authors.affiliation: Smithsonian Environmental Research Center, LHZ, BGD, Box 28, 21037, Edgewater, MD, USA.
authors.forename: L H
authors.initials: LH
authors.lastname: Ziska
authors.affiliation: Smithsonian Tropical Research Institute, KPH, APS, Apartado, 2072, Balboa, Panama.
authors.forename: K P
authors.initials: KP
authors.lastname: Hogan
authors.affiliation: Smithsonian Tropical Research Institute, KPH, APS, Apartado, 2072, Balboa, Panama.
authors.forename: A P
authors.initials: AP
authors.lastname: Smith
authors.affiliation: Smithsonian Environmental Research Center, LHZ, BGD, Box 28, 21037, Edgewater, MD, USA.
authors.forename: B G
authors.initials: BG
authors.lastname: Drake
keywords: A/Ci; C3; CAM; Pi regeneration; RuBP carboxylase