Juvenile mortality and attacks by a specialist herbivore increase with conspecific adult basal area of Amazonian <i>Swietenia macrophylla</i> (Meliaceae)
Why this work is in the frame
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Bibliographic record
Abstract
According to the Janzen–Connell model, host-specific natural enemies can promote species coexistence of canopy trees in tropical forests by attacking progeny where they are most concentrated. However, empirical evidence relating negative density-dependent mortality to herbivory and, in particular, attack by specialist herbivores, remains rare. We investigated density dependence in a natural population of Swietenia macrophylla in a south-eastern Amazon forest of Brazil. Across 24 adult trees, we found that initial juvenile densities were positively correlated with basal area of adult conspecifics whereas subsequent survivorship over 1 y for these juveniles declined strongly with increasing basal area of adult conspecifics. For 18 trees with > 5 juveniles surviving for 1 y, further evidence supporting the Janzen–Connell mechanism was obtained in that leaf herbivory and attack by a specialist microlepidopteran moth ( Steniscadia poliophaea ) increased, and overall foliar condition decreased, with conspecific basal area. Moreover, when differences in mean juvenile size (number of extant leaves) were accounted for, juvenile survival over 1 y decreased with increased specialist leaf herbivory. Collectively, these results indicate that herbivores, in particular S. poliophaea , may contribute to density dependence among S. macrophylla juveniles. We conclude that the survival of juveniles and their probability of recruitment into the canopy is decreased where conspecific adults are largest and/or most numerous and find support for the importance of host-specific pests in driving density dependence among tropical trees.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 it