Dataset Information

Increasing stomatal conductance in response to rising atmospheric CO2.

ABSTRACT: Background and Aims:Studies have indicated that plant stomatal conductance (gs) decreases in response to elevated atmospheric CO2, a phenomenon of significance for the global hydrological cycle. However, gs increases across certain CO2 ranges have been predicted by optimization models. The aim of this work was to demonstrate that under certain environmental conditions, gs can increase in response to elevated CO2. Methods:Using (1) an extensive, up-to-date synthesis of gs responses in free air CO2 enrichment (FACE)experiments, (2) in situ measurements across four biomes showing dynamic gs responses to a CO2 rise of ~50 ppm (characterizing the change in this greenhouse gas over the past three decades) and (3) a photosynthesis-stomatal conductance model, it is demonstrated that gs can in some cases increase in response to increasing atmospheric CO2. Key Results:Field observations are corroborated by an extensive synthesis of gs responses in FACE experiments showing that 11.8 % of gs responses under experimentally elevated CO2 are positive. They are further supported by a strong data-model fit (r2 = 0.607) using a stomatal optimization model applied to the field gs dataset. A parameter space identified in the Farquhar-Ball-Berry photosynthesis-stomatal conductance model confirms field observations of increasing gs under elevated CO2 in hot dry conditions. Contrary to the general assumption, positive gs responses to elevated CO2, although relatively rare, are a feature of woody taxa adapted to warm, low-humidity conditions, and this response is also demonstrated in global simulations using the Community Land Model (CLM4). Conclusions:The results contradict the over-simplistic notion that global vegetation always responds with decreasing gs to elevated CO2, a finding that has important implications for predicting future vegetation feedbacks on the hydrological cycle at the regional level.

SUBMITTER: Purcell C

PROVIDER: S-EPMC5946907 | biostudies-other | 2018 May

REPOSITORIES: biostudies-other

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Increasing stomatal conductance in response to rising atmospheric CO2.

Purcell C C Batke S P SP Yiotis C C Caballero R R Soh W K WK Murray M M McElwain J C JC

Annals of botany 20180501 6

<h4>Background and aims</h4>Studies have indicated that plant stomatal conductance (gs) decreases in response to elevated atmospheric CO2, a phenomenon of significance for the global hydrological cycle. However, gs increases across certain CO2 ranges have been predicted by optimization models. The aim of this work was to demonstrate that under certain environmental conditions, gs can increase in response to elevated CO2.<h4>Methods</h4>Using (1) an extensive, up-to-date synthesis of gs responses ...[more]

PMID: 29394303

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Project description:Rising atmospheric CO 2 and ocean acidification are fundamentally altering conditions for life of all marine organisms, including phytoplankton. Differences in CO 2 related physiology between major phytoplankton taxa lead to differences in their ability to take up and utilize CO 2. These differences may cause predictable shifts in the composition of marine phytoplankton communities in response to rising atmospheric CO 2. We report an experiment in which seven species of marine phytoplankton, belonging to four major taxonomic groups (cyanobacteria, chlorophytes, diatoms, and coccolithophores), were grown at both ambient (500 μatm) and future (1,000 μatm) CO 2 levels. These phytoplankton were grown as individual species, as cultures of pairs of species and as a community assemblage of all seven species in two culture regimes (high-nitrogen batch cultures and lower-nitrogen semicontinuous cultures, although not under nitrogen limitation). All phytoplankton species tested in this study increased their growth rates under elevated CO 2 independent of the culture regime. We also find that, despite species-specific variation in growth response to high CO 2, the identity of major taxonomic groups provides a good prediction of changes in population growth and competitive ability under high CO 2. The CO 2-induced growth response is a good predictor of CO 2-induced changes in competition (R2 > .93) and community composition (R2 > .73). This study suggests that it may be possible to infer how marine phytoplankton communities respond to rising CO 2 levels from the knowledge of the physiology of major taxonomic groups, but that these predictions may require further characterization of these traits across a diversity of growth conditions. These findings must be validated in the context of limitation by other nutrients. Also, in natural communities of phytoplankton, numerous other factors that may all respond to changes in CO2, including nitrogen fixation, grazing, and variation in the limiting resource will likely complicate this prediction.

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Increasing stomatal conductance in response to rising atmospheric CO2.

Publications

Increasing stomatal conductance in response to rising atmospheric CO2.

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