Postglacial record of diatom assemblage changes related to climate in an alpine lake in the northern Rocky Mountains, Canada
Bibliographic record
Abstract
We relate changes in diatom assemblages to Holocene climate since ca. 10 300 cal. years BP at a small (4 ha), alkaline, alpine tundra lake in the Rocky Mountains of northeast British Columbia. A complex of small benthic Fragilaria-type taxa generally dominated the fossil diatom communities reflecting shallow, alkaline, and likely low light conditions resulting from minerogenic turbidity or extensive ice cover throughout the Holocene. Shifts in diatom assemblages occurred with changes in local vegetation, inferred from pollen and stomate records, and shifts in charcoal-inferred fire frequency (e.g., lowering of tree line and reduced fire frequency (approx. 7500 cal. years BP) and establishment of modern alpine tundra (approx. 3500 cal. years BP). Importantly, striking changes in diatom communities (e.g., during the mid-Holocene (approx. 5500 to approx. 3500 cal. years BP) and Medieval Warm Period (approx. AD 800 to approx. AD 1250)) occurred without evidence of vegetation shifts. During these times, diverse periphytic diatoms dominated suggesting improved benthic habitat availability with longer growing seasons and probably reduced alkalinity and turbidity with warmer- and wetter-than-present climates. Diatom analysis from this alpine lake provides a sensitive record of climate-related limnological responses, but also refines our previous understanding of Holocene climate changes in the northern Rocky Mountains inferred from terrestrial-based paleoecological records.Key words: alkalinity, alpine lakes, climate change, diatoms, Holocene, paleolimnology.
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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 | 0.000 |
| 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".