Effects of nitrogen and phosphorus amendments on CO <sub>2</sub> and CH <sub>4</sub> production in peat soils of Scotty Creek, Northwest Territories: potential considerations for wildfire and permafrost thaw impacts on peatland carbon exchanges
Bibliographic record
Abstract
Abstract. Impacts of nutrient enrichment on soil carbon cycling have been extensively studied in temperate and tropical regions where intensive agriculture and land development has led to large increases in anthropogenic inputs of nitrogen (N) and phosphorous (P). However, how soil carbon sequestration and soil–atmosphere gas exchanges in cold regions respond to greater inputs of N and P remains poorly known despite recent observations showing significant increases in porewater N and P in burned subarctic peatlands and downstream waters. Wildfires and enhanced hydrological connectivity due to permafrost thaw therefore have the potential to change carbon turnover and gas emissions in the soils of northern peatlands. To start exploring the sensitivity of peatland soil biogeochemistry to variations in N and P availability, we measured the carbon dioxide (CO2) and methane (CH4) production rates during a month-long incubation experiment with soils from a bog and fen collected at the long-term Scotty Creek research station in the Northwest Territories, Canada. Sub-samples of the peatland soils were divided into containers to which artificial porewater solutions were added. These solutions were amended with either dissolved inorganic N, dissolved inorganic P, or dissolved N and P together. Unamended controls were run in parallel. The containers were cycled through pre-set temperature steps of 1, 5, 15, and 25 °C. Overall, the fen soil yielded higher CO2 and CH4 production rates than the bog soil. The amendment of N in the bog soil produced more CO2 compared to its control, while the amendment of P increased CO2 production in the fen soil. The amendment of N and P together reduced CO2 production but increased that of CH4 in both the fen and bog soil incubations. Porewater chemistry at the end of the 30 d experiment showed aqueous C, N, and P stoichiometric ratios that trended toward those of the soil microbial biomasses, hence implying that the initial microbial nutrient status played a crucial role in determining the responses to the different nutrient amendments. Our results demonstrate that porewater nutrient availability and soil carbon cycling interact in complex ways to change CO2 and CH4 production rates in peatland soils, with potentially far-reaching implications for the impacts of wildfires and permafrost thaw on peatland–atmosphere carbon exchanges.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".