Fraxinus pennsylvanica trees growing along the central Assiniboine river floodplain, Central Canada: Flood rings, quantitative wood anatomy and blue intensity.
Notice bibliographique
Résumé
In recent decades, visual identification of flood rings (event years) has been successfully used to document historic high-magnitude spring floods. In Fraxinus spp., flood rings usually have more numerous earlywood vessels and/or earlywood vessels with smaller cross-sectional area than observed in "normal" years. Visual identification of flood rings has also shown to be reproductible. In more recent times, quantitative wood anatomy of earlywood features (continuous time series) has, among other, been successfully used to reconstruct spring flow and associated flood conditions. In Interior North America, most paleoflood studies have focused on visually identifying flood rings in bur oak (Quercus macrocarpa Michx.) trees growing along river terraces; the idea being that in these “high” elevation sites only high-magnitude floods may be recorded. In this study, we reexamined tree-ring samples collected in 2004-2005 from 87 green ash (Fraxinus pennsylvanica Marsh.) trees growing in four floodplain sites (~20 trees per site) located in the central Assiniboine river watershed i.e., in Spruce Wood Provincial Park, Manitoba. Flood rings were visually searched in all samples and compiled during the crossdating procedure. Earlywood vessels (area ≥ 1000 µ2) were measured in five trees selected from each of the four floodplain sites. In addition, we determined from a subset of these trees the blue intensity from high-resolution scans of tree-rings and compared them, among others, to the earlywood vessel characteristics. Developed chronologies were compared to both regional climate and hydrological records. They were also compared to former flood-ring studies using bur oak trees growing on terraces in the upper Assiniboine river and/or the lower and upper Red river. Results indicated that visual identification of flood rings in F. pennsylvanica was reproductible. Both the relative frequency of flood rings and earlywood mean vessel area were significantly associated with winter precipitations, spring snow cover, spring temperatures and spring runoff records. Some of the years recording the most flood rings were 1948, 1955, 1956, 1976 and 1995. These years corresponded to documented major floods for the central Assiniboine river. They, however, poorly coincided to those observed in bur oak trees growing on terraces along the upper Assiniboine river and the Red river (e.g., 1950, 1979, 1997). These results highlight, among others, the differences between tree species, habitat selection as well as between the rivers’ flood dynamics. We argue that floodplain trees compared to terrace trees, and especially when old individuals are available, may provide a clearer overall picture of flood dynamics and of long-term hydroclimatic changes as they capture conditions leading to both small and large floods. At this time, blue intensity analyses of the floodplain trees remain to be completed. Given than flood rings have been associated with low density earlywood, it is hypothesized that blue intensity (a proxy for tree-ring density) may yield potential in paleoflood studies.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».