Acclimation to light in planted and naturally regenerated populations of white spruce seedlings
Bibliographic record
Abstract
Physiological responses to sun and shade were examined in white spruce (Picea glauca (Moench) Voss) seedlings collected from three naturally regenerated (N1-N3) and three planted (P1-P3) stands in the boreal forest of Saskatchewan. Seedling survival was greater in the sun than in the shade pretreatment periods. Dark respiration declined by 70% in shade- compared with sun-acclimated seedlings; however, the decline was not statistically significant because of the large within-population variation. Quantum yield, total chlorophyll content, specific leaf area, and absolute water content of needles increased by 45, 33, 32, and 50%, respectively, in response to shade. At low light levels, shade-acclimated populations showed greater photosynthetic rates and steeper light-response curves than seedlings growing in full sun. Seedlings of P3, N2. and N3 saturated at about 200 µmol·m-2·s-1 PAR in the shade, with no increase in photosynthesis at higher light intensities. At light saturation, populations P1 and N3 showed similar photosynthetic rates to both light acclimation regimes; populations P2, P3, and N2 had lower light-saturated photosynthesis in sun, compared with shade pretreatment. Only in N1 was photosynthetic rate greater after sun than shade pretreatment; this population behaved like a "sun" and "shade" population depending on pretreatment. Differences in physiological responses to light among populations suggest the presence of more than one ecotype. N1 showed the greatest plasticity in response to light pretreatment. The remaining populations behaved more like shade-adapted populations, with little adjustment to light conditions. Intrapopulation variation was large for both regeneration types. It appears that selection pressure during reforestation was not great enough to cause a decline in intrapopulation variation in planted compared with naturally regenerated white spruce seedlings.Key words: Picea glauca, white spruce, light acclimation, photosynthesis.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| 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 source (direct Gemma or distilled Codex), 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".