Decoding the seasonal clock of sugar maple: Timings and sequence of its phenological events
Bibliographic record
Abstract
• The sequence of different phenological events across the annual cycle of maple was studied • Onset of tension driven water transport resulted in the end of sugar season • Leaf expansion and radial growth followed two weeks and four weeks after the onset of tension driven water transport, respectively • Radial growth ended in late summer, while leaves were still in trees • Ending of xylem water movement caused leaf fall in maples The seasonal sequence of physiological processes is essential to understand the strategies of carbon allocation and the dynamics of sap production in maple. We monitored the phenological events in sugar maple (Acer saccharum Marsh.) from 2018 to 2022 in Simoncouche (QC), Canada. We measured sap exudation, xylem water transport and radial growth using rain gauges and dendrometers installed on four adult trees. Leaf phenology was estimated with MODIS-derived Normalized Difference Vegetation Index (NDVI) in maple stands near the study site. The sugar season started in late March and ended in early May, at the onset of tension-driven water transport. The sugar season corresponded with the period of snowmelt and increase in soil water content. Budbreak and complete leaf expansion were observed one and three weeks after the ending of sap exudation, respectively, when the snow had disappeared and soil temperature started rising. Radial growth occurred two weeks after leaf expansion and ended in early August. The cessation of xylem water transport caused leaf fall in early November. Phenology advanced up to three weeks during the warm spring 2021. The synchronism between the sugar season and tension-driven water transport confirms the physiological limit for sap exudation, suggesting the importance of optimizing yield within the time window of rehydration after winter dormancy. In the context of ongoing climate warming, producers could benefit from paying more attention to the environmental and physiological signals triggering the sap season rather than relying solely on historical calendars of sap production.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 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".