Effects of precommercial thinning on annual radial growth and wood density in balsam fir (Abies balsamea)
Bibliographic record
Abstract
This study examined effects of precommercial thinning (PCT) on annual radial growth (ring width) and wood density in balsam fir [Abies balsamea (L.) Mill.]. In addition, the responses to PCT were measured and compared at several stem heights (0.2 m, 0.7 m, 1.3 m, 3 m, 5 m, 7 m, 9 m). Fifty-four trees were collected from plots subjected to moderate thinning (nominal stand density of 2,150 stems/ha), and light thinning (nominal stand density of 4,200 stems/ha), and from control plots. Ring width and wood density of individual rings were measured by X-ray densitometry. Our results show that in balsam fir the annual radial growth rate showed a positive response to PCT, especially in the low part of the stem (up to 5 m high), and this response lasted for 7 years. To achieve a significant increase in annual diameter growth in this species, however, a moderate thinning intensity is needed. This study also revealed that the response of annual radial growth to PCT was limited primarily to the earlywood width, whereas the latewood width showed little response. As a result, the latewood percentage was affected by the moderate thinning. The light thinning and the control plots, however, had a comparable earlywood width and latewood percentage. Both earlywood density and latewood density showed little response to PCT. However, the wood density of growth rings tended to decrease following the moderate thinning, due to a decreased latewood percentage. In addition, the moderate thinning might somehow reduce the intra-ring variation in wood density and thus produce more uniform wood. This study also revealed that the responses to thinning in this species tended to weaken appreciably with increasing stem height. The remarkable responses were observed in the low part of the stem (up to 5 m high), whereas little response was found at the upper part of the stem. As a result, an increased stem taper may result from PCT in balsam fir.
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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".