Modern<i>Sphagnum</i><i>δ</i><sup>13</sup>C signatures follow a surface moisture gradient in two boreal peat bogs, James Bay lowlands, Québec
Bibliographic record
Abstract
Abstract Carbon isotopic composition of Sphagnum macrofossils can potentially be used as a palaeohydrological tool for peat‐based climatic studies since a relationship between Sphagnum δ 13 C values and peatland surface moisture has been presented in previous studies. In order to verify this hypothesis, modern Sphagnum δ 13 C values were measured along a moisture (microtopographic) gradient in two boreal peat bogs. Isotopic measurements were performed on bulk material of S. fuscum , S. magellanicum , S. capillifolium and S. pulchrum . Isotopic variations found within and between Sphagnum species along the microtopographic gradient were compared using analysis of variance. A significant positive correlation ( P < 0.0001) was found between Sphagnum δ 13 C values and their position along the surface moisture gradient. Results show that 13 C‐depleted values are related to low water table depths (WTD), while 13 C‐enriched values correspond to a water table that is close to the peat surface. Although the mechanisms underlying carbon fractionation processes in mosses are not well understood, we demonstrate that water resistance to CO 2 diffusion is an important fractionation process that is observed in bulk Sphagnum δ 13 C measurements, since drier and wetter samples exhibit consistent and very different isotopic signatures. Copyright © 2008 John Wiley & Sons, Ltd.
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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 | 0.000 |
| Science and technology studies | 0.001 | 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".