Niches, null models, and forest birds: Testing competing community assembly hypotheses in disturbed and undisturbed hardwood forest
Bibliographic record
Abstract
Processes that structure bird communities can be divided into two general categories: niche-based and dispersal-based. By examining the proportion of coniferous specialist individuals and the species composition in two forest bird communities, we tested the relative importance of habitat preference and availability (niche-based process) versus random settlement of individuals (dispersal-based process) in determining community composition. We examined two sites on Cape Breton Island, Nova Scotia, Canada: one undisturbed, the other with a history of human disturbance. To test for random settlement, for each forest type we generated model communities based on a random selection of individuals, weighted by the relative proportions of individuals and species in the observed community. In both communities, the proportion of individuals that were coniferous specialists deviated from random. In the disturbed forest, the proportion of coniferous specialist species increased as coniferous habitat increased, consistent with an effect of habitat preference and availability on community structure. This effect was not evident in the undisturbed forest. The proportion of coniferous specialist species, especially at the disturbed site, was similar to the proportion produced by our random model, a different result than for individuals. Examining results only at the species level may mask the processes operating at the level of individuals. Total species richness at both sites was accurately predicted by our random model, suggesting that species richness may be independent of the processes that determine community composition.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| 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".