Xylogenesis in black spruce subjected to rain exclusion in the field 1
Bibliographic record
Abstract
The predicted climate warming and more frequent and longer droughts are expected to produce potentially severe water stresses in the boreal forest. The aim of this experiment was to study the effect of a summer drought on xylem phenology and anatomy of mature black spruce (Picea mariana (Mill.) BSP) trees in their natural environment. The trees were excluded from rain during June-September 2010 by the installation of under-canopy roofs in four sites of the boreal forest of Quebec. Xylem phenology, stem radius variations, and physiological traits of treated and control trees were monitored at short time resolution. At the end of the growth season, cell characteristics were measured. The rain exclusion reduced the cell area of the xylem, but no significant change was observed in cell wall thickness, cell production, or phenology. Stem radius variations of the treated trees were lower but followed the same pattern as the control. After removal of the exclusion, trees and soil quickly recovered their normal water status. One summer of drought led to the formation of smaller tracheids but showed that black spruce is resistant to this rain exclusion treatment. This is likely due to the ability to collect water from sources other than the superficial soil horizon. \n \nL’augmentation de la température et des périodes de sècheresse plus extrêmes et plus fréquentes prévues produiront des stress hydriques potentiellement sévères dans la forêt boréale. Le but de cette expérience était d’étudier l’effet de la sècheresse estivale sur la phénologie et l’anatomie du xylème des épinettes noires (Picea mariana (Mill.) BSP) matures en milieu naturel. Les arbres ont été exclus de la précipitation de juin à septembre 2010. Des toiles imperméables ont été installées sous la canopée dans quatre sites de la forêt boréale de Québec. Le développement du xylème, la variation radiale du tronc et les traits physiologiques des arbres traités et témoins ont été surveillés à une haute résolution temporelle. À la fin de la saison de croissance les caractéristiques cellulaires ont été mesurées. L’exclusion de la pluie a diminué la superficie des cellules du xylème, mais aucun changement signicatif n’a été observé dans l’épaisseur des parois, la quantité des cellules ou leur phénologie. Les variations radiales du tronc des arbres traités étaient plus basses mais suivaient le même motif que celles des témoins. Après avoir retiré les toiles imperméables, le sol et les arbres ont rapidement récupéré leur statut hydrique normal. Un été de sècheresse à entraîné la formation des trachéides plus petits, mais démontre que l’épinette noire est résistante au traitement d’exclusion de pluie. L’espèce a probablement une capacité de récupérer l’eau provenant de sources autres que le sol superficiel.
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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 | 0.001 |
| 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) | 0.006 | 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".