A comparative kinetic analysis of nitrate and ammonium influx in two early‐successional tree species of temperate and boreal forest ecosystems
Bibliographic record
Abstract
ABSTRACT Root NO3− and NH4+ influx systems of two early‐successional species of temperate (trembling aspen: Populus tremuloides Michx.) and boreal (lodgepole pine: Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) forest ecosystems were characterized. NO3− and NH4+ influxes were biphasic, consisting of saturable high‐affinity (HATS) and constitutive non‐saturable low‐affinity transport systems (LATS) that were evident at low and relatively high N concentrations, respectively. NO3− influx via HATS was inducible (IHATS); nitrate pre‐treatment resulted in 8–10‐fold increases in the Vmax for influx in both species. By contrast, HATS for NH4+ were entirely constitutive. In both species, Vmax values for NH4+ influx were higher than those for NO3− uptake; the differences were larger in pine (6‐fold) than aspen (1·8‐fold). In aspen, the Km for NH4+ influx by HATS was approximately 3‐fold higher than for IHATS NO3− influx, while in pine the Km for IHATS NO3− influx was approximately 3‐fold higher than for NH4+ influx. The aspen IHATS for NO3− influx appeared to be more efficient than that of pine (Vmax values for aspen being approximately 10‐fold higher and Km values being approximately 13‐fold lower than for pine). By contrast, only small differences in values for the NH4+ HATS were evident between the two species. The kinetic parameters observed here probably result from adaptations to the N availabilities in their respective natural habitats; these may contribute to the distribution and niche separation of these species.
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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".