<i>Sphagnum</i>-dominated Peatlands in North America Since the Last Glacial Maximum: Their Occurrence and Extent
Bibliographic record
Abstract
Sphagnum-dominated peatlands occupy extensive tracts of land throughout the Boreal and Subarctic regions of North America, extending north onto the Low Arctic of the Canadian Shield and south along the west coast of Oregon, Rocky Mountains of Wyoming, and Appalachians of West Virginia. In addition, short pocosins found along the southeastern coast also can be considered as Sphagnum-dominated peatlands, even though they differ significantly from traditional concepts of boreal peatlands. Along the southern limit of Sphagnum-dominated peatlands, where climate is limiting, edaphic factors allow for the development of outliers. As the current distribution of Sphagnum-dominated peatlands is related to Sphagnum spore rain, past distributions of Sphagnum-dominated peatlands can be constructed from spore records preserved in lakes and peatlands. Here we present six time slices extending back to the Last Glacial Maximum to determine how Sphagnum-dominated peatlands have varied in both time and space. The spore record indicates that Sphagnum-dominated peatlands were present in North America during the Last Glacial Maximum although they were spatially limited to central Alaska, the Olympic Peninsula and Puget Trough of Washington, and to a narrow band in the eastern states of Kentucky, North Carolina, Tennessee, and Maryland. During the Late Wisconsinan Sphagnum-dominated peatlands shifted northwards in eastern North America and expanded farther into Alaska and the Midwest. The Late Wisconsinan/Holocene transition marks a time of overall increase in the area supporting Sphagnum-dominated peatlands, while extending farther in eastern Canada and western continental and coastal regions, they almost completely disappear in the Midwest where they were extensive earlier. Sphagnum-dominated peatlands generally reach their current extent about 2,000–3,000 years ago. Sphagnum-dominated peatlands have dramatically changed their distribution and abundance since the Last Glacial Maximum, and hence the carbon that is stored in these present-day important sinks has also changed dramatically. When compared to the estimated 220 Pg of carbon stored in North American peatlands today, less than 10% of this carbon was present in these peatland during the LGM.
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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 | 0.001 | 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) | 0.001 | 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".