Abstract
Impacts of springtime frost and ozone enrichment, alone and in combination, on six birch (Betula pendula Roth) genotypes regenerated from a naturally occurring birch stand in southeastern Finland were studied. The seedlings were exposed to 65 ppb ozone (AOT40 (accumulated over a threshold of 40 ppb) exposure of 10.7 ppm·h) over 62 d in climate chambers, simulating spring conditions, and to 2 °C over two consecutive nights 33 d after the start of the experiment. The plants were measured for net photosynthesis, stomatal conductance, and concentrations of photosynthetic pigments, Rubisco, soluble proteins, carbohydrates, and macronutrients. Frost treatment caused a rapid 60%77% decline in net photosynthesis and stomatal conductance rates. Recovery of net photosynthesis from frost was not complete during the subsequent 14 d, mainly because of impaired light capture through significant pigment loss and structural injuries. Concomitant ozone enrichment exacerbated the negative effect of frost on pigments and stomatal conductance. Both frost and ozone caused nutrient imbalance and increase in soluble proteins in leaves, whereas metabolism of carbohydrates was disturbed only when ozone was present. Responses to ozone and frost varied greatly among the genotypes, suggesting that there is a high capacity within the birch population to adapt to climate change through "preadapted" individuals.
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Claims 7
Claim · model-written summary
Frost reduced birch net photosynthesis and stomatal conductance by 60% to 77%.
- Taxon
- Betula pendula
Betula pendulat0 - Treatment
- Frost treatmente0
- Outcome
- net photosynthesis and stomatal conductance ratese0
- Direction
- declinee0
- Value
- 60%77%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Frost treatment caused a rapid 60%77% decline in net photosynthesis and stomatal conductance rates”
t0“birch (Betula pendula)”
Claim · model-written summary
Birch net photosynthesis did not fully recover during the following 14 days after frost.
- Taxon
- Betula pendulaBetula pendulat0
- Treatment
- froste0
- Outcome
- Recovery of net photosynthesise0
- Direction
- not completee0
- Value
- 14 de0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Recovery of net photosynthesis from frost was not complete during the subsequent 14 d”
t0“Betula pendula”
Claim · model-written summary
The incomplete recovery was attributed mainly to pigment loss and structural injuries impairing light capture.
- Taxon
- Betula pendulaBetula pendulat0
- Outcome
- impaired light capturee0
- Qualifier
- significant pigment loss and structural injuriese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“mainly because of impaired light capture through significant pigment loss and structural injuries”
t0“Betula pendula”
Claim · model-written summary
Ozone enrichment worsened frost damage to birch pigments and stomatal conductance.
- Taxon
- Betula pendulaBetula pendulat0
- Treatment
- Concomitant ozone enrichmente0
- Outcome
- pigments and stomatal conductancee0
- Direction
- exacerbatede0
- Comparator
- froste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Concomitant ozone enrichment exacerbated the negative effect of frost on pigments and stomatal conductance”
t0“Betula pendula”
Claim · model-written summary
Both frost and ozone caused nutrient imbalance and increased soluble leaf proteins.
- Taxon
- Betula pendulaBetula pendulat0
- Organ / stage
- leavese0
- Treatment
- Both frost and ozonee0
- Outcome
- nutrient imbalance and increase in soluble proteinse0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both frost and ozone caused nutrient imbalance and increase in soluble proteins in leaves”
t0“Betula pendula”
Claim · model-written summary
Carbohydrate metabolism was disturbed only with ozone exposure.
- Taxon
- Betula pendulaBetula pendulat0
- Treatment
- ozonee0
- Outcome
- metabolism of carbohydratese0
- Direction
- disturbede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“metabolism of carbohydrates was disturbed only when ozone was present”
t0“Betula pendula”
Claim · model-written summary
Birch genotypes varied greatly in responses to ozone and frost.
- Taxon
- Betula pendulaBetula pendulat0
- Material
- genotypese0
- Outcome
- Responses to ozone and froste0
- Direction
- varied greatlye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Responses to ozone and frost varied greatly among the genotypes”
t0“Betula pendula”
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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.