A simple soil moisture index for representing multi-year drought impacts on aspen productivity in the western Canadian interior
Notice bibliographique
Résumé
Tree ring studies have shown that drought is a major factor governing growth of aspen (Populus tremuloides Michx.) forests in western Canada. Previous analyses showed that interannual variation in aspen radial growth is moderately well-correlated with a climate moisture index (CMI), calculated annually as the difference between precipitation (P) and potential evapotranspiration (PE). However, there are multi-year lags, where current year growth is significantly related to CMI over each of the preceding 5 years. We postulated that such lags arise because of tree growth responses to soil water content, which in deep soils may change slowly in response to interannual variation in P and PE. To address this, a model was developed that simulates changes in a soil moisture index (SMI) from inputs of P and PE only. The SMI represents the quantity of available soil water (mm) for aspen forest evapotranspiration and growth, and also provides a measure of relative soil water content (θr). Model performance was tested using measurements made at an intensively instrumented boreal aspen stand in Saskatchewan, Canada, over a 9-year period that included an exceptionally severe drought (2001–2003). Following optimization of the equations describing soil water limitations on evapotranspiration, the model was successful in simulating the observed, monthly variation in θr (r2 = 0.86–0.88). The model was then used to estimate historic variation in the SMI across a regional network of aspen stands where historical variation in growth was reconstructed from tree-rings. Subsequent analyses showed that average SMI during the current growing season was comparable to the CMI in its ability to explain temporal variation in aspen growth. However, the multi-year lags associated with the CMI were no longer statistically significant when the SMI was used as the independent moisture variable. In a case study of aspen stands that had been free of significant defoliation by insects, tree-ring analysis showed that growth was significantly related to CMI in each of the preceding 5 years, but was significantly related to SMI only in the current year and the preceding year. Thus, hydrological lags can explain much of the apparent delay in aspen growth responses to moisture, and future tree-ring studies may benefit from using modeled SMI as a more realistic index for assessing drought impacts on the productivity of aspen and other forest types.
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) | 0,001 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,001 | 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 ».