Photosynthesis of birch (<i>Betula pendula</i>) is sensitive to springtime frost and ozone
Bibliographic record
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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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".