Effects of high atmospheric CO₂ concentration on root hydraulic conductivity of conifers depend on species identity and inorganic nitrogen source

Gebauer, Tobias; BassiriRad, H.

Effects of high atmospheric CO₂ concentration on root hydraulic conductivity of conifers depend on species identity and inorganic nitrogen source

2011

Gebauer, Tobias | BassiriRad, H. (Hormoz)

We examined root hydraulic conductivity (Lₚ) responses of one-year-old seedlings of four conifers to the combined effects of elevated CO₂ and inorganic nitrogen (N) sources. We found marked interspecific differences in Lₚ responses to high CO₂ ranging from a 37% increase in P. abies to a 27% decrease in P. menziesii, but these effects depended on N source. The results indicate that CO₂ effects on root water transport may be coupled to leaf area responses under nitrate (NO₃ ⁻), but not ammonium (NH₄ ⁺) dominated soils. To our knowledge, this is the first study that highlights the role of inorganic N source and species identity as critical factors that determine plant hydraulic responses to rising atmospheric CO₂ levels. The results have important implications for understanding root biology in a changing climate and for models designed to predict feedbacks between rising atmospheric CO₂, N deposition, and ecohydrology.

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