Carbon dioxide, methane, and nitrous oxide exchanges in an age‐sequence of temperate pine forests
Bibliographic record
Abstract
Abstract We investigated soil carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O) exchanges in an age‐sequence (4, 17, 32, 67 years old) of eastern white pine ( Pinus strobus L.) forests in southern Ontario, Canada, for the period of mid‐April to mid‐December in 2006 and 2007. For both CH 4 and N 2 O, we observed uptake and emission ranging from −160 to 245 μg CH 4 m −2 h −1 and −52 to 21 μg N 2 O m −2 h −1 , respectively (negative values indicate uptake). Mean fluxes from mid‐April to mid‐December across the 4, 17, 32, 67 years old stands were similar for CO 2 fluxes (259, 246, 220, and 250 mg CO 2 m −2 h −1 , respectively), without pattern for N 2 O fluxes (−3.7, 1.5, −2.2, and −7.6 μg N 2 O m −2 h −1 , respectively), whereas the uptake rates of CH 4 increased with stand age (6.4, −7.9, −10.8, and −23.3 μg CH 4 m −2 h −1 , respectively). For the same period, the combined contribution of CH 4 and N 2 O exchanges to the global warming potential (GWP) calculated from net ecosystem exchange of CO 2 and aggregated soil exchanges of CH 4 and N 2 O was on average 4%, <1%, <1%, and 2% for the 4, 17, 32, 67 years old stand, respectively. Soil CO 2 fluxes correlated positively with soil temperature but had no relationship with soil moisture. We found no control of soil temperature or soil moisture on CH 4 and N 2 O fluxes, but CH 4 emission was observed following summer rainfall events. LFH layer removal reduced CO 2 emissions by 43%, increased CH 4 uptake during dry and warm soil conditions by more than twofold, but did not affect N 2 O flux. We suggest that significant alternating sink and source potentials for both CH 4 and N 2 O may occur in N‐ and soil water‐limited forest ecosystems, which constitute a large portion of forest cover in temperate areas.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.000 | 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 teacher head, 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".