Root ammonium transport efficiency as a determinant in forest colonization patterns: an hypothesis
Bibliographic record
Abstract
Ratios of ammonium (NH 4 + ) to nitrate (NO 3 – ) in soils are known to increase during forest succession. Using evidence from several previous studies, we hypothesize that a malfunction in NH 4 + transport at the membrane level might limit the persistence of early successional tree species in later seral stages. In those studies, 13 N radiotracing was used to determine unidirectional fluxes and pool sizes of NH 4 + and NO 3 – in seedlings of the late‐successional species white spruce ( Picea glauca ) and in the early successional species Douglas‐fir ( Pseudotsuga menziesii var. glauca ) and trembling aspen ( Populus tremuloides ). At high external NH 4 + , the two early successional species accumulated excessive NH 4 + in the root cytosol, and exhibited high‐velocity, low‐efficiency (15% to 22%), membrane fluxes of NH 4 + . In sharp contrast, white spruce had low cytosolic NH 4 + accumulation, and lower‐velocity but much higher‐efficiency (65%), NH 4 + fluxes. Because these divergent responses parallel known differences in tolerance and toxicity to NH 4 + amongst these species, we propose that they constitute a significant driving force in forest succession, complementing the discrimination against NO 3 – documented in white spruce (Kronzucker et al. 1997).
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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".