Comparison of ammonium, nitrate, and proton fluxes in mycorrhizal and nonmycorrhizal roots of lodgepole pine in contrasting nitrogen treatments
Bibliographic record
Abstract
Relatively few comparative studies exist of nitrogen (N) uptake by ectomycorrhizal (EM) and nonmycorrhizal roots under controlled conditions. Instantaneous and long-term N uptake by EM and nonmycorrhizal roots of lodgepole pine seedlings ( Pinus contorta (Douglas) var. latifolia (Engelm.)) were compared after 9–12 months of preconditioning under high or low N supply, with NH4+ and NO3− in proportions of 90:10 and 10:90. EM roots were inoculated with Amphinema byssoides or Laccaria bicolor. Instantaneous net NH4+, NO3−, and H+ fluxes were measured simultaneously on seedling roots with a microelectrode ion flux measurement system, and seedling organ biomass and N content were measured to infer long-term N uptake. Net NH4+ uptake was observed in EM roots of lodgepole pine but NH4+ efflux was observed in nonmycorrhizal roots. Greater instantaneous N uptake in EM roots was supported by higher root and shoot N contents in seedlings associated with L. bicolor than in noninoculated seedlings. Absence of NH4+ efflux in EM roots suggests that root colonization by EM fungi has the potential to reduce futile cycling of NH4+. EM lodgepole pine appeared to prefer NH4+ over NO3− as an N source and instantaneous NH4+ uptake rates were higher in NH4-starved roots. H+ efflux was observed in most roots. Future work should focus on a greater variety of EM species to explore differences among species in N uptake.
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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".