Clarifying the Role of Wildfires and Permafrost Thaw in Brownification in a Shallow Boreal Lake Using Paleolimnological Analyses of Diatom Assemblage Change
Bibliographic record
Abstract
Permafrost thaw in discontinuous permafrost peatlands has been linked to enhanced export of chromophoric dissolved organic matter (cDOM) into lakes, reducing water clarity through ‘lake brownification’. In the Dehcho region (Northwest Territories, Canada), diatom (siliceous algae, Class Bacillariophyceae) assemblages in small, shallow lakes have been shown to be structured along a cDOM gradient, indicating that lake brownification can be inferred from subfossil diatoms in lake sediment cores. This thesis presents the results of a diatom-based paleolimnological study of a small, shallow Dehcho lake covering the last ~300 years. Results indicate a shift beginning circa ~1920s from epiphytic and large-sized diatom taxa characteristic of low cDOM lakes (Denticula kuetzingii, Navicula) towards increased abundance of Pseudostaurosira brevistriata and Stauroforma exiguiformis associated with higher cDOM. The timing of this shift coincided with an anomalous sediment geochemical signature potentially indicative of a drought or wildfire that likely initiated an accelerated loss of permafrost.
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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 | 0.000 | 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) | 0.001 | 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".