Hillslope hydrologic influences on soil dissolved organic carbon fate informs extreme precipitation impacts on boreal forest mineral soil stocks
Bibliographic record
Abstract
In boreal forests dissolved organic carbon (DOC) from organic soil layers supports chelation of metals forming organometal complexes (OMCs), a major form of stabilized soil organic carbon (SOC) in mineral soil. However, the effectiveness of OMCs likely depends on the degree to which they are saturated by carbon. We studied DOC retention in mineral soil from contrasting hillslope positions in a humid boreal forest to help address two key questions: (1) How do soil and pre-event conditions impact SOC response to extreme precipitation events? (2) Does this response vary by hillslope position? Soil collected from both low-relief upslope and steep footslope sites, were subjected to a sequence of additions of organic soil solutions over a range of soil moisture conditions. Results of linear-mixed models assessing the effect of soil position, moisture, and OMC carbon saturation indicate variation in DOC retention is largely (75%) explained by the carbon saturation of aluminum OMCs. Soil moisture conditions prior to DOC addition and soil solution DOC concentration explained much of the remaining variation. These results help explain the greater SOC content and its steeper decline with depth in the upslope low-relief soils relative to the steeper footslope soils. The relatively C-saturated surface soils exhibited DOC loss with rewetting suggesting enhanced SOC loss with extreme precipitation on dry shallow mineral soils. Conversely, C-undersaturated deeper soils consistently retained DOC, particularly in low-relief upslope soils where greater infiltration transports DOC to depth supporting adsorption by undersaturated OMCs, indicating deep SOC storage potential. In steeper footslope soils, however, greater lateral flow may limit deeper DOC supply and thus SOC accrual. By combining hillslope soil observations with laboratory experimentation, we find evidence suggesting the fate of DOC infiltrating through and across soil profiles is impacted by hydrologic processes and the degree to which OMCs are saturated with C.
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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".