Within-crown Foliar Plasticity of Western Hemlock, Tsuga heterophylla, in Relation to Stand Age
Bibliographic record
Abstract
Anatomy and morphology of needles from six different positions within the crowns of western hemlock, Tsuga heterophylla (Raf.) Sarg., were studied to investigate the plastic response of leaf structure to crown position, in relation to stand age. Trees were sampled from three stands, all of which originated following catastrophic fires, representing a chronosequence (15, 55 and 145 years old) of stand development. Needles from the highest and outermost crown positions showed morphological and anatomical responses normally associated with ‘sun leaves’. As a measure of expressed plasticity, we calculated a relative trait range (RTR) index to quantify differences in expressed traits between needles from the upper outer crown (UO needles) and those from the lower inner crown (LI needles). RTR was positive for most morphological and anatomical traits, indicating larger trait measurements on UO needles relative to LI needles (e.g. UO needles were thicker and had more vascular tissue than LI needles). However, the degree to which sun and shade leaf traits were expressed varied between stands. In the youngest stand, UO needles had higher maximal rates of photosynthesis than LI needles (positive RTR Ps ), but this trend was reversed in the oldest stand (negative RTR Ps ). Mean RTR across all morphological and anatomical traits was higher in the 145-year-old stand than in either the 55-year-old stand ( P = 0·03) or the 15-year-old stand ( P < 0·01). While this probably relates mainly to differences in light conditions between the three stands, it may also indicate a connection between ontogeny and phenotypic plasticity. Copyright 2001 Annals of Botany Company
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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 | 0.001 | 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) | 0.000 | 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".