Origin of the lichen–spruce woodland in the closed‐crown forest zone of eastern Canada
Bibliographic record
Abstract
ABSTRACT Aim We investigate the timing and factors responsible for the transformation of closed‐crown forests into lichen–spruce woodlands. Location The study area extends between 70° and 72° W in the closed‐crown forest zone from its southern limit near 47°30′ N to its northern limit at the contact with the lichen–spruce woodland zone around 52°10′ N. A total of 24 lichen–spruce woodlands were selected. Methods Radiocarbon dating of charcoals at mineral soil contact and within the organic horizons allowed the principal factors causing the degradation of the closed‐crown forest to be identified, i.e. light fires, successive fires and the occurrence of a spruce budworm epidemic followed by a fire. Results Charcoals dated in the organic horizon were less than 200 years old, suggesting a recent transformation of the closed‐crown forest following surface fires. Before their transformation into lichen–spruce woodlands, stands were occupied by old, dense forests that originated from fires dating back to 1000 yr bp . The radiocarbon dating of charcoals in the organic horizon indicated that several stands burned twice in less than 50 years, while others burned shortly after a spruce budworm epidemic. Light fires are frequent within the lichen–spruce woodlands according to multiple charcoal layers found within the organic matter horizon. Main conclusions While closed‐crown forests are predicted to expand under climate warming, compound disturbances diminish the natural regeneration of the closed‐crown forests in the south and favour the expansion of lichen–spruce woodlands. As black spruce germinates on mineral soils, surface fires accentuate the expansion of the lichen–spruce woodlands southward. Under global warming, warmer springs will lead to earlier low‐intensity fires that do not remove as much organic matter, and hence prevent conditions suitable for black spruce regeneration. Also, spruce budworm reduces seed production for a certain time. The occurrence of fire during this period is critical for regeneration of black spruce.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.000 | 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 teacher head, 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".