Nursery stock type, nitrogen fertilization and shoot pruning effects on the growth of juvenile hybrid poplar in Saskatchewan
Bibliographic record
Abstract
Increased demand for wood from the forest-products and bio-energy industries in Canada has generated interest in large-scale hybrid poplar production for the prairie-boreal transition region. Because of the harsh climate and short growing season, this region of Canada poses significant challenges for establishment and production of hybrid poplar plantations and currently little silviculture information specific to this region is available. Trials were established at two sites with different prior land use histories: a former alfalfa field and a mixed-grass pasture. Cutting (Ct), rooted cutting (RCt) and rooted plug (RPg) nursery stock of hybrid poplar [P. deltoides × (P. laurifolia × P. nigra) var. Walker] were established with two fertilization rates (0 and 100 kg N ha-1) and pruned and unpruned treatments. Despite the alfalfa site having higher amounts of available N than the pasture site and tree growth being superior at the alfalfa site, foliar N concentrations indicated an N deficiency at the alfalfa site in 2003. The difference in growth between sites was attributed to a higher degree of weed competition at the pasture site. Survival of saplings was affected by the nursery stocks. The presence of roots on the initial stock was key to early survival with approximately 92% of rooted stocks surviving over winter the first year of planting, and only 41% of unrooted cuttings surviving the same period. The short growing seasons (115 to 127 frost-free days) provided enough time for RCt to recover from pruning and produce stem volumes larger than unpruned trees. For reasons unknown, RPg did not fully recover from pruning and stem volumes in 2003 and 2004 were lower than unpruned trees. Although expectations of rates of growth of hybrid poplar are lower in the prairie-boreal transition region of Canada compared with regions of North America with more moderate climates, establishment of plantations can be realized with aggressive weed control and selection of rooted stock materials. Key words: Cuttings, rooted cuttings, rooted plugs, cultural practices, Walker
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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 | 0.001 |
| Science and technology studies | 0.001 | 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".