Bulk density, particle density, and porosity of two species of <i>Sphagnum</i> : Variability in measurement techniques and spatial distribution
Bibliographic record
Abstract
Abstract Peatlands store more carbon than the world's forests combined, despite covering only 3% of Earth's surface. Governing the sequestration of carbon are biogeochemical processes which are controlled largely by hydrology, which is influenced by the physical properties of the soils, such as bulk density, particle density, and porosity. Reliable values for these properties for peat can be found in the literature; however, values for Sphagnum litter, particularly particle density, are often not measured or reported. The values that do exist for Sphagnum litter rarely report the depth or any spatial differences within the peatland that might exist. Particle density of soil organic material (i.e., humus) is often assumed to be 1.4 g cm –3 and is used for litter. We sampled numerous hummocks of S. capillifolium (Ehrh.) Hedw. and S. magellanicum Brid. (now either S. divinum Flatberg & Hassel or S. medium Limpr.) at a midlatitude continental peatland and determined the bulk density, particle density, and porosity at 5‐cm intervals from the surface to 25‐cm depth. Bulk density and porosity values were similar to values reported in the literature; difference between species and location within the peatland were observed, with the largest difference being found between Sphagnum growing in open and treed areas. Particle density, however, averaged 0.75 g cm –3 , or nearly half that of the assumed value from the literature, suggesting strongly that assuming 1.4 g cm –3 is incorrect for Sphagnum litter and that peatland practitioners should use a locally obtained value, or 0.75 g cm –3 instead.
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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 | 0.001 |
| 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".