Physiological acclimation dampens initial effects of elevated temperature and atmospheric CO2 concentration in mature boreal Norway spruce |
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| Authors: | Shubhangi Lamba Marianne Hall Mats Räntfors Nitin Chaudhary Sune Linder Danielle Way Johan Uddling Göran Wallin |
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| Affiliation: | 1. Department of Biological and Environmental Sciences, University of Gothenburg, G?teborg, Sweden;2. Centre for Environmental and Climate Research, Lund University, Lund, Sweden;3. Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden;4. Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences (SLU), Alnarp, Sweden;5. Department of Biology, University of Western Ontario, London, Ontario, Canada;6. Nicholas School of the Environment, Duke University, Durham, NC, USA |
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| Abstract: | Physiological processes of terrestrial plants regulate the land–atmosphere exchange of carbon, water, and energy, yet few studies have explored the acclimation responses of mature boreal conifer trees to climate change. Here we explored the acclimation responses of photosynthesis, respiration, and stomatal conductance to elevated temperature and/or CO2 concentration (CO2]) in a 3‐year field experiment with mature boreal Norway spruce. We found that elevated CO2] decreased photosynthetic carboxylation capacity (?23% at 25 °C) and increased shoot respiration (+64% at 15 °C), while warming had no significant effects. Shoot respiration, but not photosynthetic capacity, exhibited seasonal acclimation. Stomatal conductance at light saturation and a vapour pressure deficit of 1 kPa was unaffected by elevated CO2] but significantly decreased (?27%) by warming, and the ratio of intercellular to ambient CO2] was enhanced (+17%) by elevated CO2] and decreased (?12%) by warming. Many of these responses differ from those typically observed in temperate tree species. Our results show that long‐term physiological acclimation dampens the initial stimulation of plant net carbon assimilation to elevated CO2], and of plant water use to warming. Models that do not account for these responses may thus overestimate the impacts of climate change on future boreal vegetation–atmosphere interactions. |
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| Keywords: | carboxylation efficiency intercellular CO2 concentration Picea abies transpiration Vcmax whole‐tree chambers |
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