Does Long-Term Elevation of CO2 Concentration Increase Photosynthesis in Forest Floor Vegetation? (Indiana Strawberry in a Maryland Forest).

摘要: As the partial pressure of CO2 (pCO2) in atmosphere rises, photorespiratory loss carbon C3 photosynthesis will diminish and net efficiency light-limited photosynthetic uptake should rise. We tested this expectation for Indiana strawberry (Duchesnea indica) growing on a Maryland forest floor. Open-top chambers were used to elevate pCO2 floor habitat 67 Pa paired with control providing an ambient 38 Pa. After 3.5 years, D. indica leaves grown measured elevated showed significantly greater maximum quantum (by 22%) lower light compensation point 42%) than chambers. The minimize photorespiration, 1% O2, was same controls plants at pCO2. This that light-energy transduction into assimilated not altered by acclimation increase simply function decrease photorespiration. Acclimation did ribulose-1,5-bisphosphate carboxylase/oxygenase light-harvesting chlorophyll protein content leaf more 30%. These changes associated decreased capacity light-saturated, but light-limited, photosynthesis. Even so, light-saturated rates current atmospheric In situ measurements under natural lighting large increases pCO2, relative controls, both summer fall. allowed positive days locations fluxes insufficient