Effects of fertilization and seasonality on phosphorus pools in an ombrotrophic bog
Notice bibliographique
Résumé
Nutrient cycling and nutrient status control primary productivity, decomposition, plant community composition, and microbial community composition in ombrotrophic bogs. Ombrotrophic bogs in Canada are often nitrogen and phosphorus co-limited, meaning that changes in phosphorus concentrations have dramatic effects on ombrotrophic bog ecology. To study the current state of biotic phosphorus cycling, I measured microbial and labile phosphorus concentrations in Mer Bleue Bog near Ottawa, ON over a period of 14 months. Both microbial and labile phosphorus concentrations varied greatly through the year. This variation is linked to changes in water table depth and season. High water tables were associated with higher microbial phosphorus concentrations, while low water tables were associated with lower microbial phosphorus concentrations, even in layers that remained saturated during the entire year. During a year with a mild winter, microbial phosphorus concentrations were high during late winter and during spring snowmelt, averaging 115 to 130 mg kg-1 P in layers above the water table. Microbial phosphorus concentrations then declined through the growing season as plants became more competitive, averaging 45 to 105 mg kg-1 P in layers above the water table. Labile phosphorus concentrations were often low, averaging 2 to 12 mg kg-1 P, but increased sharply to 45 mg kg-1 P in the upper layers of peat for short periods of time before being taken up by microorganisms and plants. Both microbial and labile phosphorus concentrations were highest near the surface and decreased with depth from 0 to 75 cm. To study the effects of nutrient addition and nutrient limitation on peatland soil phosphorus pools, samples were taken from the long-term fertilization experiment at Mer Bleue Bog. Samples were taken in 2021 following nearly twenty years of fertilizer application. These samples were subjected to a Hedley sequential fractionation to extract phosphorus along a chemical gradient of biological availability. In unfertilized peat, phosphorus concentrations were highest in the available and highly recalcitrant pools, with little between them. This U-shaped distribution of phosphorus along the gradient of availability contrasts with established patterns in mineral soils. In plots which received PK and NPK fertilizers, concentrations of both available phosphorus and highly recalcitrant phosphorus doubled. In plots receiving N fertilization alone, available and total P concentrations decreased, which may indicate increased demand for P by plants and microorganisms when N status is high. In all plots receiving fertilizer, concentrations of highly recalcitrant phosphorus increased, which may indicate increased decomposition of peat. In addition, fertilization led to changes aboveground. Chamaedaphne calyculata leaves in plots receiving PK and NPK were enriched in phosphorus compared to C. calyculata leaves in unfertilized plots and plots receiving N alone
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 | 0,000 | 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) | 0,000 | 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 ».