Does long-term elevation of CO{sub 2} concentration increase photosynthesis in forest floor vegetation? Indiana strawberry in a Maryland forest

Journal Article · Thu May 01 04:00:00 EDT 1997 · Plant Physiology (Bethesda)

OSTI ID:530492

Osborne, C P; Long, S P ^[1]; Drake, B G ^[2]

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1. Univ. of Essex, Colchester (United Kingdom)
2. Smithsonian Environmental Research Center, Edgewater, MD (United States); and others

As the partial pressure of CO{sub 2} (pCO{sub 2}) in the atmosphere rises, photorespiratory loss of carbon in C, photosynthesis will diminish and the net efficiency of light-limited photosynthetic carbon uptake should rise. Indiana strawberry (Duchesnea indica) growing on a Maryland forest floor was tested. Open-top chambers were used to elevate the pCO{sub 2} of a forest floor habitat to 67 Pa and were paired with control chambers with an ambient pCO{sub 2} of 38 Pa. After 3.5 years, D. indica leaves in the elevated pCO{sub 2} showed a significantly greater maximum quantum efficiency of net photosynthesis (by 22%) and a lower light compensation point (by 42%) than leaves in the control chambers. The quantum efficiency to minimize photorespiration was the same for controls and plants grown at elevated pCO{sub 2}, showing the maximum efficiency of light-energy transduction into assimilated carbon was not altered by acclimation and the increase in light-limited photosynthesis at elevated pCO{sub 2} was a function of the decrease in photorespiration. Acclimation did decrease the ribulose-1,5-bisphosphate carboxylase/oxygenase and light-harvesting chlorophyll protein content of the leaf by more than 30%. These changes were associated with a decreased capacity for light-saturated, but not light-limited, photosynthesis. Leaves of D. indica grown and measured at elevated pCO{sub 2} showed greater light-saturated photosynthetic rates than leaves grown and measured at the current atmospheric pCO{sub 2}. In situ measurements under natural lighting showed large increases in leaf photosynthesis at elevated pCO{sub 2}, relative to controls, in both summer and fall. The increase in efficiency of light-limited photosynthesis with elevated pCO{sub 2} allowed positive net photosynthetic carbon uptake on days and at locations on the forest floor that light fluxes were insufficient for positive net photosynthesis in the current atmospheric pCO{sub 2}. 33 refs., 3 figs., 3 tabs.

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 530492
• Journal Information: Plant Physiology (Bethesda), Journal Name: Plant Physiology (Bethesda) Journal Issue: 1 Vol. 114; ISSN 0032-0889; ISSN PLPHAY
• Country of Publication: United States
• Language: English

Related Subjects

56 BIOLOGY AND MEDICINE
APPLIED STUDIES
BIOLOGICAL EFFECTS
CARBON DIOXIDE
FORESTS
GROUND COVER
HERBS
PHOTOSYNTHESIS