Long-Term Impacts of Commercial Thinning and Nitrogen Fertilization on Lodgepole Pine: A Two-Decade Analysis of Growth and Temporal Dynamics
Bibliographic record
Abstract
Commercial thinning and fertilization are potential silvicultural tools to enhance Alberta’s Forest productivity in an imminent timber supply gap. In 2000, an experiment was initiated in a 68-year-old lodgepole pine stand located in Alberta’s upper foothills, using a 2x6 factorial design. Commercial thinning, removing 50% basal area was carried out at two levels (thinned and unthinned), while nitrogen fertilization was applied at six levels (No fertilizer, 200 kg/ha N Urea + Boron, 200 kg/ha N + blend, 400 kg/ha N + Boron, 400 kg/ha N + blend, and 400 kg/ha N Ammonium nitrate + Boron). Two studies were conducted, utilizing 20 years of post-thinning data, to analyze: a) the individual and combined effects of thinning and fertilization on growth and mortality and b) the temporal growth response to commercial thinning using tree cores. Key findings of the first study were that commercial thinning led to an increase in the cumulative merchantable volume (the volume removed at the time of thinning + the final standing volume) and the proportion of trees suitable for good sawlogs (>20 cm DBH) by 20%. Individual tree DBH was enhanced through thinning and fertilization treatments, both individually and in combination. This indicates that trees subject to both thinning and high fertilization (at 400 kg/ha levels) exhibited the greatest individual growth. From the second study we found the size of individual trees at the time of thinning significantly predicted their subsequent growth for both studies. Smaller trees (10.1-12.5 cm) exhibited a delayed response to thinning within the first 5 years, followed by a slow growth increment. Medium-sized trees (12.5-17.5 cm) displayed an immediate growth response to thinning but declined after 15 years. The largest trees (17.6-20 cm) exhibited a slower growth response, which persisted beyond 15 years. Consequently, commercial thinning and fertilization can serve as a viable management tool to enhance the growth of natural lodgepole pine stands in Alberta. Commercial thinning and fertilization are potential silvicultural tools to enhance Alberta’s Forest productivity in an imminent timber supply gap. In 2000, an experiment was initiated in a 68-year-old lodgepole pine stand located in Alberta’s upper foothills, using a 2x6 factorial design. Commercial thinning, removing 50% basal area was carried out at two levels (thinned and unthinned), while nitrogen fertilization was applied at six levels (No fertilizer, 200 kg/ha N Urea + Boron, 200 kg/ha N + blend, 400 kg/ha N + Boron, 400 kg/ha N + blend, and 400 kg/ha N Ammonium nitrate + Boron). Two studies were conducted, utilizing 20 years of post-thinning data, to analyze: a) the individual and combined effects of thinning and fertilization on growth and mortality and b) the temporal growth response to commercial thinning using tree cores. Key findings of the first study were that commercial thinning led to an increase in the cumulative merchantable volume (the volume removed at the time of thinning + the final standing volume) and the proportion of trees suitable for good sawlogs (>20 cm DBH) by 20%. Individual tree DBH was enhanced through thinning and fertilization treatments, both individually and in combination. This indicates that trees subject to both thinning and high fertilization (at 400 kg/ha levels) exhibited the greatest individual growth. From the second study we found the size of individual trees at the time of thinning significantly predicted their subsequent growth for both studies. Smaller trees (10.1-12.5 cm) exhibited a delayed response to thinning within the first 5 years, followed by a slow growth increment. Medium-sized trees (12.5-17.5 cm) displayed an immediate growth response to thinning but declined after 15 years. The largest trees (17.6-20 cm) exhibited a slower growth response, which persisted beyond 15 years. Consequently, commercial thinning and fertilization can serve as a viable management tool to enhance the growth of natural lodgepole pine stands in Alberta.
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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 | 0.001 | 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) | 0.000 | 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".