Carbon dioxide and methane fluxes and organic carbon accumulation in old field and northern temperate forest plantation soils
Bibliographic record
Abstract
Carbon dioxide (CO2) and methane (CH4) fluxes from the soil surface, and concentrations within the soil profile, were measured between June 1998 and Sept. 1999 at four adjacent forest plantations and an old field in Nepean, Ontario. The objectives of this study were to quantify seasonal CO2 and CH4 fluxes from the soil surface and within the soil profile to determine the effect of soil moisture and temperature, and forest age and species on the exchange, and establish a chronosequence of organic carbon accumulation in the forest plantations and the old field soils. Dynamic and static chamber techniques were used to measure surface fluxes of CO2 and CH4, respectively, and soil gas concentrations were sampled with probes. In the old field and forest plantations, surface soil CO2 flux ranged from 2.9 to 27 g CO2 m-2 d-1 and 2.0 to 39 g CO2 m -2 d-1 respectively. Significant differences due to age and species of plantation were observed. Seasonal variations in CO2 efflux from the soil surface and within the soil profile were related to variation in soil temperature and moisture. Uptake of CH4 was observed at all sites and there was no significant differences in flux due to vegetation type or age. Maximum rate of CH4 consumption was 6.3 mg CH4 m-2 d-1. Methane uptake was positively related to soil moisture conditions. The carbon content of the soil increased in all sites following the establishment of vegetation on sandy parent material. Carbon content was greatest in the upper soil profile. Rates of carbon accumulation ranged from 109 to 426 g m-2 y-1. Soil carbon increased with increasing age of plantation during the first 30 years following the establishment of vegetation on parent material, but declined as the forest plantation matured.
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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 | 0.001 | 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) | 0.000 | 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".