Controls on Terrestrial Evapotranspiration from a Forest-Wetland Complex in the Western Boreal Plain, Alberta, Canada
Notice bibliographique
Résumé
The Western Boreal Plain (WBP) of North Central Alberta consists of a mosaic wetlands and aspen (Populus tremuloides) dominated uplands. This region operates within a moisture deficit regime where precipitation (P) and evapotranspiration (ET) are the dominant hydrologic fluxes. As such these systems are extremely susceptible to the slightest to the slightest climatic variability that may upset the balance between P and ET. Vegetation composition is the dominant control on wetland ET, and itself is extremely dynamic within these wetland environments, which can be attributed to varying moisture regimes along with micrometeorological variations. To address this variability in moisture regimes ET was examined in a typical moraine wetland of the WBP during the 2005 and 2006 snow-free seasons. Closed dynamic chamber measurements were used to gather data on plant community scale actual evapotranspiration (ET) for an undisturbed natural bog with varying degrees of canopy cover surrounding a shallow groundwater fed pond. For the purposes of scaling plant community ET contributions to that of the wetland, potential ET (PETEQ) was measured using a Priestley-Taylor energy balance approach at three separate wetland sites with varying aspects surrounding the central pond, along with actual ET using a roving eddy covariance (EC) tower. Growing season peak ET rates ranged from 0.2 mm hr-1 to 0.6 mm hr-1 depending on location, vegetation composition and time period. Sphagnum contributions were the greatest early in the growing season reaching peaks of 0.6 mm hr-1, while lichen sites exhibited the greatest late season rates at 0.4 mm hr-1. Thus, Sphagnum and other non-vascular wetland plant species control ET differently throughout the growing season and as such should be considered an integral part of the moisture and water balances within wetland environments at the sub-landcover unit scale.\nUpland ET was characterized over three scales during the 2005 and 2006 snowfree seasons. Above canopy (ETC) and within canopy (ETB) were examined using the EC technique situated at 25.5 m (7.5 m above crown) and 4.0 m above the ground surface respectively. Soil evaporation (ES) was examined using a closed dynamic chamber system to gather data on surface evaporation for upland soils. ETc and ETB were controlled primarily through atmospheric demand (VPD) while Es was controlled by soil moisture (9). During the green periods ETC averaged 3.08 mm d-1 and 3.45 mm d-1 in 2005 and 2006 respectively while ETB averaged 1.56 mm d-1 and 1.95 mm d-1. Es was consistent across both snow-free seasons and averaged 0.28 mm hr-1 in 2005 and 0.31 mm hr-1 in 2006. The nature of Populus tremuloides canopies permits ample energy availability within the canopy during the early season early green periods which promotes the development of a lush understory consisting of Rosa acicularis and Viburnum edule. ETB fluxes were equal to or greater than the ETC fluxes once understory development had occurred. Upon crown growth ETB fluxes were reduced as a reduction in available energy existed. ETB fluxes ranged from 42 to 56% of ETC fluxes over the remainder of the snowfree seasons. Vapour pressure deficit (VPD) and soil moisture (0) displayed strong controls on both ETc and ETB fluxes. ETc fluxes responded to precipitation events as the developed crown intercepted and held available water which contributed to peak ETC fluxes following precipitation events >10 mm. This indicates the importance of interception in aspen dominated forest canopies of the WBF.
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 | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,001 |
| Communication savante | 0,001 | 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 ».