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EFFECTS OF ELEVATED CO2 AND TEMPERATURE ON GROWTH, BIOCHEMISTRY AND PHYSIOLOGY OF DOUGLAS-FIR
Citation:
Lewis, J. D., M G. Johnson, R B. McKane, D M. Olszyk, P T. Rygiewicz, D T. Tingey, AND M. Lucash. EFFECTS OF ELEVATED CO2 AND TEMPERATURE ON GROWTH, BIOCHEMISTRY AND PHYSIOLOGY OF DOUGLAS-FIR. Presented at Interactions Between Increasing CO2 and Temperature in Terrestrial Ecosystems, Lake Tahoe, CA, April 27-30, 2003.
Description:
We examined the interactive effects of CO2 concentration and mean annual temperature on physiology, biochemistry and growth of Douglas fir seedlings. Seedlings were grown at ambient CO2 or ambient + 200 ppm CO2 and at ambient temperature or ambient + 4 ?C. Needle gas exchange measurements were made monthly over a 21 month period, beginning 30 months after treatments were initiated and ending when seedlings were harvested. Growth in elevated CO2 significantly increased needle net photosynthetic rates, sugar concentrations, and instantaneous transpiration efficiency. In contrast, elevated CO2 significantly decreased needle Amax (maximum photosynthetic rate), stomatal conductance, transpiration rates, and chlorophyll and nitrogen concentrations, and did not significantly affect light compensation points or respiration rates. Growth in elevated temperature was associated with significant increases in all these parameters except needle sugar concentrations, which significantly decreased. Despite significant effects on needle biochemistry and physiology, elevated CO2 and elevated temperature generally did not significantly plant growth. There generally were no interactions between main effects on any plant growth, biochemical or physiological parameter. These results suggest that the effects of elevated CO2 and temperature may be additive for a given physiological or biochemical parameter, but these responses may not be good predictors for productivity responses to climate change.