Postglacial establishment and expansion of marginal populations of sugar maple in western Québec, Canada: Palynological detection and interactions with fire, climate and successional processes
Bibliographic record
Abstract
An isolated sugar maple (<i>Acer saccharum</i> Marsh.) stand is located in the boreal forest of Abitibi, about 75 km beyond its present northern range limit. When did this relatively thermophilous tree species establish after ice retreat? Were its populations more abundant than now sometimes in the past? If so, when and how did they expand then retracted? How did the species persist in boreal forest over time? What could have been the role of fire on this stand? To answer those questions, we reconstructed the postglacial fire and vegetation history from three lacustrine sediment sequences distributed along a <i>c</i>. 180 km latitudinal transect from southern boreal forests to the northern portion of deciduous forests. From north to south, those are lakes Labelle, Chasseur and Fur. We explored a procedure based on pollen accumulation rates in order to detect the probable presence of sugar maple within the lakes’ watershed. The procedure successfully indicates a sugar maple establishment <i>c.</i> 7800–5100 cal. BP at Fur, 5500–4400 cal. BP at Chasseur and <i>c.</i> 4000–2700 cal. BP at Labelle, in the north. At Fur, the subsequent sugar maple expansion happened 1 to 2 thousand years after establishment, during colder and moister climatic conditions favoring <i>Pinus strobus</i> L. replacement by <i>Betula</i> spp. <i>c.</i> 6000–5000 cal. BP. Sugar maple establishment, persistence or expansion is apparently not linked to a change in fire activity at Fur and Chasseur, but at Labelle, the species was more abundant during periods of shorter fire return intervals from 2000 to 500 years ago. Our study suggests that northern (Chasseur and Labelle) sugar maple establishment and possible expansion was probably more controlled by a complex interaction of inhibition and facilitation dynamics than by climate alone, a process reliant on the dominant vegetation’s composition and structure.
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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) | 0.001 | 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 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".