Influence of habitat availability and fire disturbance on a northern range boundary
Bibliographic record
Abstract
Abstract Aim Non‐climatic constraints on species northern range boundaries are often overlooked in attempts to predict climate‐induced range shifts. Here, we examined the effects of habitat availability and fire disturbance on the distribution of a species that transitions from being common to being found only in marginal populations at the northern boundary of its range. Location North‐western Quebec, Canada (46–51° N and 74–79° W). Taxon : Eastern white cedar ( Thuja occidentalis L.) Methods We used forest inventory data ( n = 4,987) to characterize white‐cedar habitat based on edaphic and topographic conditions at sampled sites along a 600‐km latitudinal gradient. Non‐metric multidimensional scaling was used to assess habitat similarity of sites in the south, where white‐cedar stands are abundant, and sites in the north, where white‐cedar stands are rare. We constructed ensemble white cedar distribution models based on habitat variables in the south and compared ensemble forecast projections of white cedar in the north with observed occurrences to determine if habitat availability was limiting. We independently estimated the age of white‐cedar stands and adjacent stands without white cedar along the gradient. ANOVA was performed to test the age difference between white‐cedar and adjacent stands to determine whether the location of white‐cedar stands was influenced by disturbance, primarily stand‐replacing fire. Results Habitat availability was not limiting the distribution of eastern white cedar at its northern range boundary. White cedar did not occupy most sites with suitable habitat in the north, suggesting that other factors prevent white cedar from establishing more stands northward. White‐cedar stands were older than adjacent stands without white cedar all along the gradient, but the difference was more pronounced in the north. This suggests that white‐cedar stands in the north are restricted to undisturbed areas. Main conclusions Fire disturbance, more than habitat availability, limits the distribution of white cedar at its northern range boundary. Projections of white cedar distribution under climate change that ignore fire could overestimate the ability of warming temperatures to extend its northern range limit.
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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) | 0.001 | 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 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".