Net photosynthesis as a function of carbon dioxide concentration in pine trees grown at ambient and elevated CO2
1994
Garcia, R.L. | Idso, S.B. | Kimball, B.A.
Pinus eldarica seedlings were grown in a field of Avondale loam at Phoenix, Arizona within transparent open-top enclosures maintained for 15 months at mean CO2 concentrations of 402 and 788 μl1l−1, after which whole-tree net photosynthetic rates were measured at a number of CO2 concentrations ranging from ambient (360 μl l−1) to 3000 μl l−1. Rates of the low-CO2-treatment trees saturated at approximately five times their ambient-concentration value; while rates of the high-CO2-treatment trees rose linearly across the entire CO2 range investigated to more than 10 times their value at 360 μl l−1. These findings suggest that long-term exposure to elevated CO2 can increase the ability of trees with unrestricted root systems to respond positively to still higher CO2 concentrations.
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