Shifting Mineral and Redox Controls on Carbon Cycling in Seasonally Flooded Soils
Bibliographic record
Abstract
Abstract. Soils contain three times the amount of carbon (C) than the atmosphere, with C turnover times ranging from centuries to millennia. Although wetland soils represent a relatively small portion of the terrestrial landscape, they account for an estimated 20–30 % of the global C reservoir. Among wetlands, seasonally flooded soils are likely the most vulnerable to increased severity and duration of droughts in response to climate change. Yet, the relative influence of associated changes in oxygen limitations, root dynamics, and mineral protection on C cycling in seasonally flooded mineral soils is largely unknown. To address this knowledge gap, we combined seasonal monitoring of soil moisture, redox potential, and CO2 efflux with a characterization of root biomass, mineralogy, C quantity and organic matter composition along upland-to-lowland transects of both top- and subsoils in temperate forested wetlands. We found that lower CO2 effluxes in lowland than upland topsoils coincided with greater total C concentrations as well as a greater abundance of high molecular weight and chemically reduced organic compounds, indicating that selective preservation of organic compounds during anaerobic periods caused C accumulation in seasonally flooded surface soils. In subsoils, however, seasonal flooding and associated anaerobic conditions did not result in soil C accumulation. Instead, total C concentrations were significantly lower in lowland than in upland subsoils. Lower soil C accumulation in seasonally flooded subsoils coincided with lower abundance of root biomass and reducible Fe phases, and relied primarily on non-reducible Al phases rather than anaerobic conditions. Combined, our results demonstrate that seasonal flooding and associated anaerobic conditions accumulate C in topsoils, but limit C accumulation in subsoils by restricting root C inputs and removing of protective Fe phases through reductive dissolution. Our findings indicate that C accrual in seasonally flooded soil is due primarily to oxygen limitations in the surface soil, and that the overall lack of mineral protection leaves these C stocks highly vulnerable to climate change.
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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 | 0.000 | 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 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".