Stomatal responses of Douglas‐fir seedlings to elevated carbon dioxide and temperature during the third and fourth years of exposure

• Published in: Plant, cell and environment Vol. 25; no. 11; pp. 1411 - 1421
• Main Authors: Lewis, J. D., Lucash, M., Olszyk, D. M., Tingey, D. T.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science, Ltd 01.11.2002; Blackwell; Wiley Subscription Services, Inc
• Subjects: Agricultural and forest climatology and meteorology. Irrigation. Drainage; Agricultural and forest meteorology; Agronomy. Soil science and plant productions; Animal and plant ecology; Animal, plant and microbial ecology; Autoecology; Biological and medical sciences; climate change; Climatic adaptation. Acclimatization; Douglas‐fir; elevated CO2; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; leaf water relations; Metabolism; photosynthesis; Photosynthesis, respiration. Anabolism, catabolism; Plant physiology and development; Plants and fungi; Pseudotsuga menziesii; seasonal patterns; stomatal conductance; temperature; transpiration; Ecotoxicology; Plant juvenile growth stage; Needle (conifer); Carbon dioxide; Stomatal conductance; Temperature effect; Stomata; Plant leaf; Water use efficiency; Ecophysiology; Pseudotsuga menziesii; Water regime; Softwood forest tree; Gymnospermae; Coniferales; Spermatophyta; Gas exchange; Photosynthesis; Climate modification
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1046/j.1365-3040.2002.00923.x

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.