The response of black spruce to the climatic influence of Robert-Bourassa Reservoir in northern Québec
Bibliographic record
Abstract
Do large hydroelectric reservoirs in northern Québec have an influence on regional climate? In the absence of any climatic record covering the period prior to and after damming, the influence of a reservoir was studied by means of tree rings. The objective of this research was to determine the reaction of black spruce to local climate change. The study was carried out on an island in the second-largest reservoir of the La Grande complex in the James Bay area, the Robert-Bourassa Reservoir (2835 km2), which is also the oldest (dammed in 1978 and completely flooded in September 1979). Trees (n = 14) about 100 years old were selected by means of two perpendicular transects on the island. Cross sections were cut at 1-m intervals at the base of trees, and at 10-cm intervals in the top section of the stem which developed during the last 30 years. Densitometric analysis was performed on each section. Results were compared with two reference chronologies using the same tree-ring parameters. Reference stands were selected outside the area of climatic influence of the reservoir. The identified tree-ring indicators of reservoir local climate were (i) absence of frost rings, despite their abundance outside the reservoir’s area of influence, due to a delayed growing season caused by local cool conditions; (ii) high frequency of light rings related to cooler summer conditions; (iii) large numbers of trees showing compression wood sequences indicating destabilization due to windier conditions associated with the increased fetch; (iv) lower annual wood production; (v) degradation of tree growth forms marked by massive foliage loss and branch mortality; and (vi) reduced wood density, despite increased proportion of latewood. The number of trees that showed these six tree-ring indicators was a function of distance to water and stand density.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 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 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".