Interactive effects of elevated CO2 and temperature on water transport inponderosa pine |
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Authors: | Maherali H Delucia E H |
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Institution: | Department of Plant Biology, University of Illinois at Urbana-Champaign, 265 Morrill Hall, 505 South Goodwin Avenue, Urbana, Illinois 61801, USA. |
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Abstract: | Many studies report that water flux through trees declines in response to elevated CO2, but this response may be modified by exposure to increased temperatures. To determine whether elevated CO2 and temperature interact to affect hydraulic conductivity, we grew ponderosa pine seedlings for 24 wk in growth chambers with one of four atmospheric CO2 concentrations (350, 550, 750, and 1100 ppm) and either a low (15°C nights, 25°C days) or high (20°C nights, 30°C days) temperature treatment. Vapor pressure deficits were also higher in the elevated temperature treatment. Seedling biomass increased with CO2 concentration but was not affected by temperature. Root : shoot ratio was unaffected by CO2 and temperature. Leaf : sapwood area ratio (AL/AS) declined in response to elevated temperature but was not influenced by CO2. Larger tracheid diameters at elevated temperature caused an increase in xylem-specific hydraulic conductivity (KS). The increase in KS and decrease in AL/AS led to higher leaf-specific hydraulic conductivity (KL) at elevated temperature. Stomatal conductance (gS) was correlated with KL across all treatments. Neither KS, KL, nor gS were affected by elevated CO2 concentrations. High KL in response to elevated temperature may support increased transpiration or reduce the incidence of xylem cavitation in ponderosa pine in future, warmer climates. |
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Keywords: | biomass allocation CO2 hydraulic conductivity leaf : sapwood area ratio Pinaceae Pinus ponderosa stomatal conductance temperature xylem anatomy |
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