Ecological status of American chestnut (<i>Castanea</i><i>dentata</i>) in its native range in Canada
Bibliographic record
Abstract
American chestnut (Castanea dentata (Marsh.) Borkh.) was once a dominant tree in eastern deciduous forests of North America and is now endangered in Canada, primarily because of the introduction of a fungal pathogen (Cryphonectria parasitica (Murrill) Barr) causing chestnut blight. A recovery plan is being developed, and more accurate information on the status of this species in its native range in southern Ontario is needed to assist in the restoration and management of this species. We conducted a 2-year inventory of the distribution and size of trees throughout southern Ontario, and characterized the habitat and incidence of blight. In total, 682 trees were sampled, 601 of which were not planted. Individuals were statistically most likely to occur in deciduous forest habitats with high canopy cover (>50%), gentle slopes (0°10°), and acidic (pH 46), sandy (>75%) soils. Most trees were small (80% were <20 cm diameter at breast height (DBH)) and nonreproductive (86%). Blight cankers were visible on only 25% of trees. Of six habitat variables measured, canopy cover was positively related to tree size (height, DBH) and incidence of blight. Litter depth was also a good predictor of cankers and virulent cankers in particular, but not healing and (or) healed cankers. The presence of Acer and Quercus spp. in the canopy was associated with reduced incidence and number of cankers per tree but increased frequencies of healing and (or) healed cankers, while Carya was correlated with increased incidence and number of cankers per tree. The abundance of American chestnut and the number of blight-free trees in southern Ontario is higher than previously known. The importance of canopy density and associated species in the habitat for tree health will contribute to the development of further research programs and management strategies for the restoration of this endangered species.
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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 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 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".