Abstract
Net CO 2 exchange rates (CERs) were measured in seedlings of two loblotly pine ( Pinus taeda L.) families following 6‐ or 13‐week exposures to ozone (charcoalfiltered or ambient air + O 3 ) and acid rain treatments (pH 3.3, 4.5 and 5.2). Ozone exposures (14 or 170 nl l −1 ) were made in open‐top chambers, and in continously stirred tank reactors (14, 160 or 320 nl l −1 ) located in the field and laboratory, respectively. The CERs of whole shoots were measured in an open infrared gas analysis system at 6 levels of photosynthetic photon flux density (0, 33, 60, 410, 800 and 1660 μmol m −2 s −1 ). Treatment effects were not consistent between field‐ and laboratory‐exposed seedlings. Ozone‐treated field seedlings exhibited statistically significant reductions in light‐saturated CER of 12.5 and 25% when measured at 6 and 13 weeks, respectively. Laboratory seedlings exhibited mixed responses to O 3 , with one family showing reduced CER only after 6 weeks of O 3 exposure and the other only after 13 weeks (O 3 >160 nl l −1 for both). After 13 weeks of exposure, pH 3.3, and 4.5 rain treatments enhanced light‐saturated CER by an average of 52% over that observed in seedlings exposed to the pH 5.2 treatment. Enhanced CERs due to acid rain were of the same magnitude (3–5 μmol CO 2 g −1 s −1 ) as ozone‐induced CER reductions. No differences in dark respiration were detected between treatments. Although ozone and acid rain treatments altered seedling CER, the differences were not translated into altered final plant dry weights over the 13‐week exposure period.
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Claims 8
Claim · model-written summary
Ozone reduced light-saturated CER in field pine seedlings by 12.5% after 6 weeks.
- Taxon
- Pinus taeda L.
Pinus taedae1 - Treatment
- Ozone‐treatede0
- Outcome
- light‐saturated CERe0
- Direction
- reductionse0
- Value
- 12.5e0
- Qualifier
- 6 and 13 weekse0
- Setting
- fielde0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ozone‐treated field seedlings exhibited statistically significant reductions in light‐saturated CER of 12.5 and 25% when measured at 6 and 13 weeks, respectively”
e1“Pinus taeda L.”
Claim · model-written summary
Ozone reduced light-saturated CER in field pine seedlings by 25% after 13 weeks.
- Taxon
- Pinus taeda L.Pinus taedae1
- Treatment
- Ozone‐treatede0
- Outcome
- light‐saturated CERe0
- Direction
- reductionse0
- Value
- 25%e0
- Qualifier
- 13 weekse0
- Setting
- fielde0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ozone‐treated field seedlings exhibited statistically significant reductions in light‐saturated CER of 12.5 and 25% when measured at 6 and 13 weeks, respectively”
e1“Pinus taeda L.”
Claim · model-written summary
One laboratory pine family had reduced CER only after 6 weeks of ozone exposure.
- Taxon
- Pinus taeda L.Pinus taedae1
- Treatment
- O 3 exposuree0
- Outcome
- CERe0
- Direction
- reducede0
- Qualifier
- only after 6 weekse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“one family showing reduced CER only after 6 weeks of O 3 exposure”
e1“Pinus taeda L.”
Claim · model-written summary
The other laboratory pine family had reduced CER only after 13 weeks at ozone above 160 nl l −1.
- Taxon
- Pinus taeda L.Pinus taedae2
- Treatment
- O 3 >160 nl l −1e0
- Outcome
- CERe1
- Direction
- reducede1
- Qualifier
- only after 13 weekse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the other only after 13 weeks (O 3 >160 nl l −1 for both)”
e1“Laboratory seedlings exhibited mixed responses to O 3 , with one family showing reduced CER”
e2“Pinus taeda L.”
Claim · model-written summary
Acid rain at pH 3.3 and 4.5 enhanced pine light-saturated CER by 52% relative to pH 5.2 after 13 weeks.
- Taxon
- Pinus taeda L.Pinus taedae1
- Treatment
- pH 3.3, and 4.5 rain treatmentse0
- Outcome
- light‐saturated CERe0
- Direction
- enhancede0
- Value
- 52%e0
- Comparator
- pH 5.2 treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“pH 3.3, and 4.5 rain treatments enhanced light‐saturated CER by an average of 52% over that observed in seedlings exposed to the pH 5.2 treatment”
e1“Pinus taeda L.”
Claim · model-written summary
Acid rain CER enhancement was 3–5 μmol CO 2 g −1 s −1, matching ozone-related reductions.
- Taxon
- Pinus taeda L.Pinus taedae1
- Outcome
- CERse0
- Direction
- Enhancede0
- Value
- 3–5 μmol CO 2 g −1 s −1e0
- Comparator
- ozone‐induced CER reductionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Enhanced CERs due to acid rain were of the same magnitude (3–5 μmol CO 2 g −1 s −1 ) as ozone‐induced CER reductions”
e1“Pinus taeda L.”
Claim · model-written summary
Dark respiration did not differ between treatments.
- Taxon
- Pinus taeda L.Pinus taedae1
- Outcome
- dark respiratione0
- Direction
- No differencese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“No differences in dark respiration were detected between treatments”
e1“Pinus taeda L.”
Claim · model-written summary
The ozone and acid rain treatments did not alter final plant dry weight over 13 weeks.
- Taxon
- Pinus taeda L.Pinus taedae1
- Treatment
- ozone and acid rain treatmentse0
- Outcome
- final plant dry weightse0
- Direction
- not translated into alterede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“ozone and acid rain treatments altered seedling CER, the differences were not translated into altered final plant dry weights over the 13‐week exposure period”
e1“Pinus taeda L.”
The same questions in other papers
ozone · growth · Pinus taeda (loblolly pine)Results differ
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- no effect
- negative
- negative
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See all 14 papers →rainfall · growth · Pinus taeda (loblolly pine)Positive and negative results
5 papers in the same direction as this paper · 2 in the opposite direction
- no effect
- positive
- positive
4 papers more in this group
See all 8 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.