Abstract
Woody tissue photosynthesis (Pwt) contributes to the tree carbon (C) budget and generally stimulates radial stem growth under ambient atmospheric CO2 concentration (aCO2). Moreover, Pwt has potential to enhance tree survival under changing climates by delaying negative effects of drought stress on tree hydraulic functioning. However, the relevance of Pwt on tree performance under elevated atmospheric CO2 concentration (eCO2) remains unexplored. To fill this knowledge gap, 1-year-old Populus tremula L. seedlings were grown in two treatment chambers at aCO2 and eCO2 (400 and 660 ppm, respectively), and woody tissues of half of the seedlings in each treatment chamber were light-excluded to prevent Pwt. Radial stem growth, sap flow, leaf photosynthesis and stomatal and canopy conductance were measured throughout the growing season, and the concentration of non-structural carbohydrates (NSC) in stem tissues was determined at the end of the experiment. Fuelled by eCO2, an increase in stem growth of 18 and 50% was observed in control and light-excluded trees, respectively. Woody tissue photosynthesis increased radial stem growth by 39% under aCO2, while, surprisingly, no impact of Pwt on stem growth was observed under eCO2. By the end of the growing season, eCO2 and Pwt had little effect on stem growth, leaf photosynthesis acclimated to eCO2, but stomatal conductance did not, and homeostatic stem NSC pools were observed among combined treatments. Our results highlight that eCO2 potentially fulfils plant C requirements, limiting the contribution of Pwt to stem growth as atmospheric [CO2] rises, and that radial stem growth in young developing trees was C (source) limited during early phenological stages but transitioned towards sink-driven control at the end of the growing season.
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Claims 10
Claim · model-written summary
Elevated CO2 increased stem growth of control trees by 18%.
PopulusOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fuelled by eCO2, an increase in stem growth of 18 and 50% was observed in control and light-excluded trees, respectively”
t0“poplar trees”
Claim · model-written summary
Elevated CO2 increased stem growth of light-excluded trees by 50%.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fuelled by eCO2, an increase in stem growth of 18 and 50% was observed in control and light-excluded trees, respectively”
t0“poplar trees”
Claim · model-written summary
Woody tissue photosynthesis increased radial stem growth by 39% under ambient CO2.
- Treatment
- Woody tissue photosynthesise0
- Outcome
- radial stem growthe0
- Direction
- increasede0
- Value
- 39%e0
- Qualifier
- under aCO2e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Woody tissue photosynthesis increased radial stem growth by 39% under aCO2”
t0“poplar trees”
Claim · model-written summary
Woody tissue photosynthesis had no observed impact on stem growth under elevated CO2.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“no impact of Pwt on stem growth was observed under eCO2”
t0“poplar trees”
Claim · model-written summary
Elevated CO2 and woody tissue photosynthesis had little effect on stem growth late in the season.
- Treatment
- eCO2 and Pwte0
- Outcome
- stem growthe0
- Direction
- little effecte0
- Qualifier
- By the end of the growing seasone0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“By the end of the growing season, eCO2 and Pwt had little effect on stem growth”
t0“poplar trees”
Claim · model-written summary
Leaf photosynthesis acclimated to elevated CO2.
- Outcome
- leaf photosynthesis acclimated to eCO2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“leaf photosynthesis acclimated to eCO2”
t0“poplar trees”
Claim · model-written summary
Stomatal conductance did not acclimate to elevated CO2.
- Outcome
- stomatal conductance did note0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“stomatal conductance did not”
t0“poplar trees”
Claim · model-written summary
Stem NSC pools remained homeostatic across combined treatments.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“homeostatic stem NSC pools were observed among combined treatments”
t0“poplar trees”
Claim · model-written summary
The authors infer elevated CO2 can fulfill plant carbon requirements and limit the growth contribution of woody photosynthesis.
- Treatment
- eCO2e0
- Outcome
- contribution of Pwt to stem growthe0
- Qualifier
- potentially fulfils plant C requirementse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“eCO2 potentially fulfils plant C requirements, limiting the contribution of Pwt to stem growth as atmospheric [CO2] rises”
t0“poplar trees”
Claim · model-written summary
Radial stem growth was carbon source limited early and shifted toward sink control late in the season.
- Outcome
- radial stem growthe0
- Qualifier
- C (source) limited during early phenological stages but transitioned towards sink-driven control at the end of the growing seasone0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“radial stem growth in young developing trees was C (source) limited during early phenological stages but transitioned towards sink-driven control at the end of the growing season”
t0“poplar trees”
The same questions in other papers
co2 · growth · Populus (poplar)Results differ
17 papers in the same direction as this paper · 1 in the opposite direction
- positive
- positive
- no effect
15 papers more in this group
See all 19 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.