Landscape heterogeneity and response of lake ecosystems to changes in climate and peatland expansion over the past 7500 years at the tundra-forest border of northern Manitoba, Canada
Bibliographic record
Abstract
Responses of Arctic lakes to climate change are complex and heterogeneous at regional to local scales, but there are few studies comparing multiple sites within the same landscape. We studied sediment cores recovered from seven lake sites located within the forest-tundra biome of northern Manitoba, Canada. We first used sediment core pollen from the seven sites to reconstruct July temperatures and total annual precipitation for the past 7500 years based on the modern analog technique. Lake responses and peatland expansion were analyzed based on changes in the concentration and quality of organic matter, biogenic silica (bSi), Sphagnum spores, and published peat core basal dates. Changes in sediment organic matter and bSi were concentrated prior to 4500 cal. Yr BP. From 7500 to 3100 cal. Yr BP, July temperatures rose by ~3°C, and total annual precipitation fell by 200 mm; there was little change in temperature or precipitation after 3100 cal. Yr BP. Sphagnum spore concentrations exceeded 0.5% at all of the sites at 7500 cal. Yr BP indicating the early presence of peatlands. Spores increased markedly after 4500 cal. Yr BP in agreement with timing of peat basal dates, but the magnitude and timing of changes varied widely among sites likely reflecting local differences in hydrology or topography. The use of hierarchical generalized additive models provided a unified regional pattern of Holocene climate for northern Manitoba, even though lake responses to climate and peatland expansion differed greatly.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| 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".