The palaeoecological record of gray birch (<i>Betula populifolia</i>) in eastern North America
Bibliographic record
Abstract
Gray birch (Betula populifolia Marshall) is a pioneer tree species that generally colonizes both poor, dry soils and disturbed sites. Its current range appears to be expanding, and it has been observed to establish gradually and often massively in ombrotrophic peatlands. We examined data from sites within and beyond its continuous range that have been subjected to macrofossil analyses to determine whether this species was more abundant during certain periods since deglaciation. The most abundant macroremains were found in the eastern United States and date from the early Holocene (11 700 – 7000 cal. BP). Gray birch was present in mixed forests in which fires were probably more frequent than today. Only a few sites, located in pine barrens that experienced recurrent fires, show a continuous presence of the species during the middle and late Holocene. Palaeoecological data suggest that the colonization of peatlands by gray birch is a recent phenomenon (20th century), and one unique in peatland history. Anthropic disturbances seem to create conditions that foster this species, which could consequently increase its range in the coming decades.
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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 | 0.000 | 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".