Wetland- and landscape-level effects on scoter (Melanitta spp.), scaup (Aythya spp.), and macroinvertebrates in wetlands of the Central Mackenzie Valley, Northwest Territories
Notice bibliographique
Résumé
North American breeding populations of scoters (Melanitta spp.) and scaup (Aythya spp.), which nest predominantly in the rapidly changing boreal forest, were over 20% lower 2005–2014 in the western boreal forest compared to long-term averages (1955–2014), yet habitat needs for these duck species remain poorly documented. The purpose of my research is to predict impacts of ongoing environmental changes on waterfowl food supplies in northern areas and to prioritize key habitats for conservation of these species. At a key waterfowl breeding site in Canada’s boreal forest, I tested three main hypotheses: (i) trophic enrichment – Wetlands located in areas burned by recent wildfires would be characterized by higher nutrient and productivity levels, and unique macroinvertebrate communities, versus those wetlands in unburned areas; (ii) foraging habitat limitation – Variables describing foraging habitat availability would be the best predictors of scoter and scaup occurrence; and (iii) scale dependency – The spatial scales at which landscape variables affected duck occurrence would correspond with home range size.\n\nTo test my first hypothesis, I measured levels of nitrogen, phosphorous, and chlorophyll-a concentrations, as well as macroinvertebrate community characteristics, in burned and unburned wetlands. Consistent with my predictions, total phosphorous and chlorophyll-a levels were approximately two-fold higher in burned than in unburned wetlands, although this effect was seasonally variable. Conversely, total nitrogen levels were similar in burned and unburned wetlands. For macroinvertebrate community composition, results were not as expected – on average, samples from burned and unburned wetlands contained similar taxa in similar abundances. To test my second and third hypotheses, I applied a multi-scale regression approach, using aerial breeding waterfowl survey data and remotely sensed landscape composition variables on unburned wetlands to evaluate relationships between landscape variables and habitat use. As predicted, wetland size correlated strongly and positively with scoter and scaup occurrence. In contrast, the amount of different land cover types correlated only weakly with occurrence. For scoters, the most important landscape variables were total number and area of waterbodies/km2, while the proportion wetland cover was the most important landscape variable for scaup followed by total waterbody area/km2. However, for both scoter and scaup, some of these relationships were negative, contrary to my predictions. I also found that scoters had a larger average scale of effect than scaup, as expected based on the size of their home ranges.\n\nTaken together, these results suggest that wetland ecosystems in the northwestern boreal forest are resilient to, and may even benefit from, moderate to severe fires under current climate conditions. However, fire impacts on aquatic ecosystems are likely to intensify as the climate warms, such that this resilience may not be maintained in coming decades. The results also suggest that scoter and scaup foraging habitat is limited in the study site and that wetland-level conservation for scoter and scaup pairs should be informed primarily by wetland characteristics (e.g., wetland size and amphipod abundance) and less so by landscape composition (e.g., proportion coniferous forest cover) surrounding wetlands. In addition, the findings indicate that future landscape-level predictive modelling for these duck species should include species-specific, scale-optimized variables and should focus on home range selection.
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 | 0,000 |
| Études des sciences et des technologies | 0,000 | 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 ».