May Temperature Drives Cambial Resumption in the Boreal Black Spruce
Bibliographic record
Abstract
The timings of the onset and ending of xylogenesis define the time window when environmental conditions are suitable for xylem formation. The relationship between the occurrence of xylem phenological events and the related climatic factors is critical to revealing how xylem formation responds to the changing climate. Given that temperature is the most important factor influencing growth in the boreal forest, we monitored air temperature and xylem phenology at five permanent plots of black spruce (Picea mariana (Mill.) BSP) along a latitudinal gradient of the boreal forest of Quebec, Canada. Microcores were collected weekly or biweekly from five to ten trees per site during the growing seasons from 2002 to 2019. We compared the relationships between air temperature and timings of the onset and termination of xylogenesis, testing the hypothesis that spring temperatures trigger the initiation of cambial activity. The onset of xylogenesis occurred from late May (DOY 149) to mid-June (DOY 163), and it terminated between late August (DOY 240) and late September (DOY 270). The spring phases of xylem phenology showed similar inter-annual variation among sites, while the variation in autumnal phases was less correlated among sites. The onset of xylogenesis was negatively correlated with the mean May temperature, and the correlations were consistent among sites, with r ranging from −0.61 to −0.77. The warmer May temperatures would advance cambial resumption, allowing the initial hypothesis that spring temperatures are a driving factor of xylogenesis to be accepted. With an increase of 1 °C in the mean May temperature, cambial resumption could be advanced by 2.7 days. Yet, no relationship between the termination of xylem phenology and monthly temperature was established, suggesting that other factors, possibly endogenous, could have affected the xylem phenology in autumn. Under warming conditions, we expect an advancement in the onset of xylogenesis, which may lengthen the growing season and potentially enhance cell production in black spruce.
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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".