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• 1. [Article] Stomatal Responses of Douglas-Fir Seedlings to Elevated Carbon Dioxide and Temperature During the Third and Fourth Years of Exposure

  Two major components of climate change, increasing atmospheric [CO2] and increasing temperature, may substantially alter the effects of water availability to plants through effects on the rate of water ...

  Citation × Citation Citation Abstract Copy Title: Stomatal Responses of Douglas-Fir Seedlings to Elevated Carbon Dioxide and Temperature During the Third and Fourth Years of Exposure Author: Lewis, James D., Lucash, Melissa S., Olszyk, David M., Tingey, David T. Year: 2002 Two major components of climate change, increasing atmospheric [CO2] and increasing temperature, may substantially alter the effects of water availability to plants through effects on the rate of water loss from leaves. We examined the interactive effects of elevated [CO2] and temperature on seasonal patterns of stomatal conductance (gs), transpiration (E) and instantaneous transpiration efficiency (ITE) in Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings. Seedlings were grown in sunlit chambers at either ambient CO2 (AC) or ambient + 180 µmol mol-1 CO2 (EC), and at ambient temperature (AT) or ambient + 3.5° C (ET) in a full-factorial design. Needle gas exchange at the target growth conditions was measured approximately monthly over 21 months. Across the study period and across temperature treatments, growth in elevated [CO2] decreased E by an average of 12% and increased ITE by an average of 46%. The absolute reduction of E associated with elevated [CO2] significantly increased with seasonal increases in the needle-to-air vapour pressure deficit (D). Across CO2 treatments, growth in elevated temperature increased E an average of 37%, and did not affect ITE. Combined, growth in elevated [CO2] and elevated temperature increased E an average of 19% compared with the ACAT treatment. The CO2 supply and growth temperature did not significantly affect stomatal sensitivity to D or the relationship between gs and net photosynthetic rates. This study suggests that elevated [CO2] may not completely ameliorate the effect of elevated temperature on E, and that climate change may substantially alter needle-level water loss and water use efficiency of Douglas-fir seedlings. Title: Stomatal Responses of Douglas-Fir Seedlings to Elevated Carbon Dioxide and Temperature During the Third and Fourth Years of Exposure Author: Lewis, James D., Lucash, Melissa S., Olszyk, David M., Tingey, David T. Year: 2002 Two major components of climate change, increasing atmospheric [CO2] and increasing temperature, may substantially alter the effects of water availability to plants through effects on the rate of water loss from leaves. We examined the interactive effects of elevated [CO2] and temperature on seasonal patterns of stomatal conductance (gs), transpiration (E) and instantaneous transpiration efficiency (ITE) in Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings. Seedlings were grown in sunlit chambers at either ambient CO2 (AC) or ambient + 180 µmol mol-1 CO2 (EC), and at ambient temperature (AT) or ambient + 3.5° C (ET) in a full-factorial design. Needle gas exchange at the target growth conditions was measured approximately monthly over 21 months. Across the study period and across temperature treatments, growth in elevated [CO2] decreased E by an average of 12% and increased ITE by an average of 46%. The absolute reduction of E associated with elevated [CO2] significantly increased with seasonal increases in the needle-to-air vapour pressure deficit (D). Across CO2 treatments, growth in elevated temperature increased E an average of 37%, and did not affect ITE. Combined, growth in elevated [CO2] and elevated temperature increased E an average of 19% compared with the ACAT treatment. The CO2 supply and growth temperature did not significantly affect stomatal sensitivity to D or the relationship between gs and net photosynthetic rates. This study suggests that elevated [CO2] may not completely ameliorate the effect of elevated temperature on E, and that climate change may substantially alter needle-level water loss and water use efficiency of Douglas-fir seedlings. Close