Multicentury reconstruction of western spruce budworm outbreaks in central British Columbia, Canada
Bibliographic record
Abstract
The western spruce budworm (Choristoneura occidentalis Freeman; WSB) is a widespread and destructive defoliator of commercially important coniferous forests in western North America. In British Columbia, Canada, Douglas-fir (Pseudotsuga menziesii) is the most prevalent host, and records show that significant outbreaks have primarily occurred in the southern interior over the last century. In the central interior of British Columbia, particularly in the Cariboo Forest Region, the most recent outbreak of western spruce budworm, which is in its second decade, has been severe and widespread. It is perhaps due to this long outbreak, which is unprecedented in duration since detailed surveys began in the 1950s, that there is an anecdotal perception that the western spruce budworm is expanding its range northward into the region, affecting Douglas-fir near the edge of its northern distribution. However, very little is known about the long-term outbreak history of western spruce budworm in the central interior of the province. In this study we used 11 Douglas-fir host chronologies and 2 regional Pinus non-host chronologies to reconstruct western spruce budworm outbreaks over a 435-year period. Standard dendrochronological techniques were used to develop tree-ring chronologies at each site and the program OUTBREAK was used to detect outbreak periods. We reconstructed 12 outbreaks starting in early 1600s with a mean return interval of 30 years. Sensitivity analysis illustrated that including light, moderate and severe intensity thresholds modified the number of reconstructed outbreaks, their duration and mean return interval. Sub-regional chronologies based on biogeoclimatic subzones and variants (BEC units), revealed strong synchrony of some outbreak events, but not all. Wavelet analysis of the sub-regional chronologies demonstrated the quasi-periodic behavior of western spruce budworm over the entire record, which averaged 32-years. By reconstructing WSB dynamics over 400 years we demonstrated that outbreaks observed over the last 40 years in the Cariboo Forest Region are not unprecedented.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.004 | 0.004 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".