Dendroclimatological and dendroglaciological investigations at Confederation and Franklin glaciers, central Coast Mountains, British Columbia, Canada
Notice bibliographique
Résumé
It has become increasingly clear that climate fluctuations during the Holocene interval were unusually frequent and rapid, and that our current understanding of the temporal and spatial distribution of these oscillations is incomplete. Little paleoenvironmental research has been undertaken on the windward side of the central Coast Mountains of British Columbia, Canada. Very high annual orographic precipitation totals, moderate annual temperatures regulated by the Pacific Ocean, and extreme topographic features result in a complex suite of microclimate conditions in this largely unstudied area. Dendroclimatological investigations conducted on a steep south-facing slope near Confederation and Franklin glaciers suggest that both mountain hemlock (Tsuga mertensiana) and subalpine fir (Abies lasiocarpa) trees at the site are limited by previous year mean and maximum summer temperatures. A regional subalpine fir chronology for the central and southern Coast Mountains indicates that subalpine fir trees at the study site experience physiological stress with warm summer temperatures, despite the high annual precipitation totals experienced there. This response is likely a result of the extreme gradient and the aspect of the slope at the sampling location, underscoring the importance of site characteristics on annual radial tree growth. Local (AD 1820-2008) and regional (AD 1700-2008) tree ring width chronologies were used to reconstruct previous July mean and maximum temperatures, explaining between 13% and 36% of the variance in climate. The proxy record features cool intervals that are comparable to other paleoenvironmental research from the region, and cyclical oscillations in temperature commonly associated with the El Niño Southern Oscillation and Pacific Decadal Oscillation. Century-scale fluctuations may be connected to changes in solar irradiance. Dendroglaciological investigations were undertaken at the confluence of the Confederation and Franklin glaciers with the intention of exploring the Holocene behaviour of low-elevation maritime glaciers in this region. These glaciers are suspected to be sensitive to variations in the mean position of winter freezing level heights and warm winter temperatures, and may respond differently to changes in climate than more continental glaciers. Buried wood samples were radiocarbon-dated and cross-dated to construct three floating chronologies. Float A (r = 0.467) suggests an early Little Ice Age advance of the two glaciers, and Float B (r = 0.466) suggests an early Tiedemann advance of Confederation Glacier. Float C (r = 0.519) is dated to the Garibaldi Phase of glacier expansion, but may not have been killed by glacial activity. The temporal synchronicity of these findings with glacial events documented throughout the region suggests a spatially coherent response of maritime and continental glaciers to the dominant climate–forcing mechanisms operating in Pacific North America throughout the late Holocene. The dendroclimatological and dendroglaciological findings of this study help to fill a spatial research gap in the current understanding of Holocene climate variations in British Columbia. Because of the complex and at times topographically-controlled response of conifers to climate in the study area, this region may provide a particular challenge in terms of reconstructing Holocene climate variability.
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 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,003 | 0,004 |
| Études des sciences et des technologies | 0,004 | 0,001 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,001 | 0,001 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,003 | 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 ».