Methane emissions may be driven by hydrogenotrophic methanogens inhabiting the stem tissues of poplar
Bibliographic record
Abstract
Summary Living trees in forests emit methane (CH 4 ) from their stems. However, the magnitudes, patterns, drivers, origins, and biogeochemical pathways of these emissions remain poorly understood. We measured in situ CH 4 fluxes in poplar stems and soils using static chambers and investigated the microbial communities of heartwood and sapwood by sequencing bacterial 16S, archaeal 16S, and fungal ITS rRNA genes. Methane emissions from poplar stems occurred throughout the sampling period. The mean CH 4 emission rate was 2.7 mg m −2 stem d −1 . Stem CH 4 emission rate increased significantly with air temperature, humidity, soil water content, and soil CH 4 fluxes, but decreased with increasing sampling height. The CO 2 reduction and methylotrophic methanogenesis were the major methanogenic pathways in wood tissues. The dominant methanogen groups detected in stem tissues were Methanobacterium , Methanobrevibacter , Rice Cluster I, Methanosarcina , Methanomassiliicoccus , Methanoculleus , and Methanomethylophilaceae. In addition, three methanotrophic genera were identified in the heartwood and sapwood – Methylocystis , Methylobacterium , and Paracoccus . Overall, stem CH 4 emissions can originate directly from the internal tissues or co‐occur from soils and stems. The co‐existence of methanogens and methanotrophs within heartwood and sapwood highlights a need for future research in the microbial mechanisms underlying stem CH 4 exchange with the atmosphere.
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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".