Effect of Rotation Age on Lumber Grade Yield, Bending Strength and Stiffness in Jack Pine ( Pinus Banksiana Lamb.) Natural Stands
Bibliographic record
Abstract
The effects of rotation age on lumber visual grade yield and lumber bending properties were studied on 142 jack pine trees sampled in three stands located in Timmins, Ontario. The stands, aged 50, 73, and 90 years were all naturally established after forest fires. The visual grading of a total of 1720 lumber pieces showed that the 50-yr-old stand produced a slightly lower Select Structural grade yield (36.1%) compared to the older stands (73 yr 42.9% and 90 yr 39.3%). When No. 2 and Better grades were combined, the 50-yr-old stand resulted in the lowest volume yield (88.2%), whereas the proportions of No. 2 and Better for the 73- and 90-yr-old stands were comparable (93.0 and 92.6%, respectively). Downgrades due to decay were much higher in the 90-yr-old stand (20.6%) than in the 73- and 50-yr-old stands (5.2% and 0%, respectively). Regarding stand productivity, the 50-yr-old stand showed the highest annual stand increment of 5.25 m3/ha/year, compared to 3.82 and 3.21 for the 73- and 90-yr-old stands, respectively. The visual grading of 782 board pieces showed no effect of stand age on board quality. In the 90-yr-old trees, wood density decreased steadily from butt to top for all the diameter classes studied (12-30 cm).The study showed that rotation age had a significant impact on lumber bending properties. The lumber bending properties for the 50-yr-old stand were significantly lower than those of the 73- and 90-yr-old stands. The lumber strength (MOR) and lumber stiffness (MOE) values for the 50-yr-old stand were about 16% lower and 19-16% lower than those of the 73- and 90-yr-old stands, respectively. However, no significant differences in lumber bending properties were found between the two older stands. From the viewpoint of lumber properties, a moderate rotation age of about 70 years is preferred in jack pine.
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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".