Ecology of northern white-cedar (Thuja occidentalis L.) stands at their northwestern limit of distribution in Manitoba, Canada
Bibliographic record
Abstract
Studies examining disjunct populations of tree species have been infrequent.The objective of this study was to characterize and compare the composition, structure, and environment of disjunct populations of northern white-cedar (Thuja occidentalis L.) to populations from its contiguous and peripheral distributions in Manitoba, Canada.Thuja occidentalis reaches its northwesterly contiguous distribution limit in southeastern Manitoba, but disjunct populations can be found approximately 300 km northwest, in the Grand Rapids/Cedar Lake area of west-central Manitoba.Forty-two stands were sampled to characterize the T. occidentalzs populations and frve community types were identified by K-means clustering.The first hypothesis stated that the disjunct populations of Z occidentalis would be restricted to locations with specif,rc environmental conditions/habitat, such as wet locations protected from fire.However, in the disjunct range this species was present in sites with xeric, mesic, and hydric moisture conditions.Stands of the disjunct range were mostly conifer dominated, as represented by the xeric and hydric community types, but there were also three stands of a mesic mixedwood community.In contrast, T. occidentalis in southeastern Manitoba only occurred in mesic and hydric moisture regimes.There was support for the second hypothesis that T. occidentalis associations would differ geographically, even though there was compositional overlap between three of the five community types.Third, it was hypothesized that the growth vigour of T. occidentalis would be reduced in the disjunct populations compared to that of the populations found in the contiguous distribution.The productivity of the three mesic mixedwood stands observed in the disjunct range contrasted with the restricted growth of the cotnmon xeric and hydric community types.In these three stands however, growth vigor was slightly lower than their contiguous counterparts.Lastly, it was hypothesized that regeneration success would be lower in the disjunct populations than the contiguous distribution, however, T. occidentalis recruitment was common in all community types, and in fact more abundant in the disjunct range than in the contiguous distribution.This thesis would not have been possible without the advice and patient support of my supervisor, Dr.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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 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".