Foliar plasticity of hybrid spruce in relation to crown position and stand age
Bibliographic record
Abstract
This study examined the foliar response of putative hybrid Engelmann × white × Sitka spruce (Picea engelmannii Parry × Picea glauca (Moench) Voss × Picea sitchensis (Bong.) Carr) needles in relation to crown position and across three stages of development (15, 55, and 145 years). We focused on the morphological and anatomical response, and used physiological measures (photosynthesis and stomatal conductance) to emphasize the important relationship between structure and function. We found that needles from the upper outer crown position were adaptated to reduce stress from evapotranspiration. Trees from the 15- and 55-year-old stands generally responded the most, and trees from the 145-year-old stand responded the least. As they mature, these spruce trees may have reduced ability to adapt to their environment. Some of our results contradict what the literature considers "typical" for sun-shade dimorphism in temperate forests. For example, in all stands, sun needles were broader than shade needles and, in the two younger stands, sun needles were larger in area, not smaller, than shade needles. Also, in the youngest stand, stomatal pores were longer on sun needles than on shade needles. There were no definite patterns in stomatal spacing with regard to crown position. Our results are indicative of the strategies adopted to increase competitiveness in a resource-limited environment. We suggest that, in the 15-year-old stand, neither water nor light is limiting; in the 55-year-old stand, both water and light are highly limiting; and in the 145-year-old stand, water is most limiting.Key words: drought, foliar plasticity, needle anatomy, photosynthesis, Picea, stand development, sun-shade.
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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 | 0.000 | 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 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".