The<i>Ammophila</i>decline: A field experiment on the effects of mineral nutrition
Bibliographic record
Abstract
American beachgrass (Ammophila breviligulata) is a pioneer plant on coastal dunes of northeastern North America, where it forms dense, monospecific stands on the foredune. Although both plant and population growth are active on the front of the foredune, stand decline sometimes occurs on the back. Several hypotheses have been proposed to explain this phenomenon. The aims of the present study were to assess the effects of mineral nutrition on the performance of adult A. breviligulata plants. In a field experiment, the response of A. breviligulata to fertilizer addition was determined on the front (in a vigorous stand) and on the back (in a decline zone) of the foredune at the Dune du Sud, Îles de la Madeleine, Québec. There were differences in substrate nutrient concentration between positions on the foredune at the beginning of the growth season: potassium was somewhat higher on the front, and nitrogen on the back of the foredune in the decline zone. However, these differences were slight and not biologically significant. On the control plots, root mass density was higher on the back than on the front of the foredune. Fertilizer addition increased the density and the mass of A. breviligulata shoots both on the front and the back of the foredune. Plants in the decline zone responded strongly to nutrient addition and performed better than those in the control plots on the front of the foredune. Thus, it seems that fertilizer addition largely overtook the effect of the factor(s) responsible for the decline. Because there were no biologically significant differences in substrate nutrient concentration between the front and the back of the foredune, and because root mass density was higher on the back (in the decline zone) than on the front of the foredune, we suggest that the decline might be associated with a lower efficiency of the roots to absorb nutrients. This might be related to differences in mycorrhiza infections between the back and the front of the foredune.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.002 |
| 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".