Effects of Nitrogen addition on Soil Phosphorus Pools in an Ombrotrophic Bog in South-Eastern Ontario, Canada
Bibliographic record
Abstract
Peatlands store about one third of the global soil organic carbon. This carbon storage is partly controlled by the availability of nitrogen (N) and phosphorus (P) in peat, which affects primary productivity, decomposition, plant community composition, and microbial community composition in these ecosystems. While extensive research has been conducted on the N cycle in peatlands, much less is known about the biogeochemistry of P. To date, little is known about how an increase of atmospheric N deposition affects the availability and biogeochemistry of P in peat. To fill this gap of knowledge, we studied the effect of increased N additions on soil P pools in an ombrotrophic bog in Canada. For this purpose, soil samples were taken from a 20 year old fertilization trial at Mer Bleue Bog in south-eastern Ontario and subjected to Hedley sequential fractionation. In unfertilized peat, P concentrations were highest in the available and highly recalcitrant pools, with little between them. This U-shaped distribution of P along the gradient of availability contrasts with established patterns in mineral soils. In plots which received PK and NPK fertilizers, concentrations of both available P and highly recalcitrant P doubled. In plots receiving N fertilization alone, available and total P concentrations decreased, which may indicate increased demand for P by plants and microorganisms when N status is high. In all plots receiving fertilizer, concentrations of highly recalcitrant P increased, which may indicate increased decomposition of peat. In addition, fertilization led to changes aboveground. Chamaedaphne calyculata leaves in plots receiving PK and NPK were enriched in P compared to Chamaedaphne calyculata leaves in unfertilized plots and plots receiving N alone. These findings indicate, that formerly N limited peatlands may become P limited due to anthropogenically enhanced atmospheric nitrogen depositions which may impact their potential to store soil organic carbon in the future.
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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 | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".