Rapid turnover of organic acids in a Dystric Brunisol under a spruce–lichen forest in northern Saskatchewan, Canada
Bibliographic record
Abstract
Fujii, K., Morioka, K., Hangs, R., Funakawa, S., Kosaki, and Anderson, D. W. 2013. Rapid turnover of organic acids in a Dystric Brunisol under a spruce-lichen forest in northern Saskatchewan, Canada. Can. J. Soil Sci. 93: 295-304. Organic acids released by lichen play an important role in mineral weathering and podzolization in the Boreal-Tundra transition zone of Canada; however, importance of low-molecular-weight organic acids in the soil carbon (C) cycle in the black spruce-lichen forests remains unclear. We examined soil solution composition and mineralization kinetics of 14C-radiolabelled oxalate and citrate to quantify the C fluxes from organic acid mineralization in a Dystric Brunisol under a spruce-lichen forest in northern Saskatchewan. Oxalate concentration in soil solution was greatest in the lichen layer, while the high levels of citrate were observed in the lichen and organic (O) layers to the Ae horizon with the lowest sorption capacity. Oxalate and citrate were rapidly mineralized within the lichen and O layers and had short mean residence times (0.5 to 2.7 h). Substantial C fluxes due to citrate mineralization were observed both within the lichen and O layers, but oxalate mineralization led to C flux in the lichen layer only. The contribution of citrate and oxalate to microbial respiration was large (up to 57%) in the surface soil layers. Citrate was the dominant substrate for microbial respiration of the surface soil; however, it appears that oxalate could also be an important microbial substrate within the lichen layer, at least in summer months. We conclude that the exudation of low-molecular-weight organic acids by lichenous fungi, followed by their rapid mineralization, could play an important role in the C cycles of the sandy soils under spruce-lichen forest.
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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 | 0.002 | 0.002 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| 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".