Beyond mountain pine beetle: soil carbon storage a decade after tree mortality and the possible influence of soil fungi
Notice bibliographique
Résumé
Mountain pine beetle (MPB; Dendroctonus ponderosae) disturbances, amplified by climate change, have led to extensive tree mortality and ecosystem succession in boreal forests across western Canada. Often following attack, former ectomycorrhizal (EM) pine stands in Alberta are replaced by arbuscular (AM) mycorrhizal shrubs and forbs. There has been growing interest in the varying ways that EM versus AM fungi influence critical soil processes, particularly concerning carbon cycling. While our comprehension of the specific impacts that MPB-induced mycorrhizal community succession has on long-term soil carbon storage remains somewhat limited, emerging frameworks offer broad yet valuable initial insights into this complex dynamic. Specifically, given the functional differences between mycorrhizal fungal types, a shift from EM- to AM-dominance in affected stands may promote soil organic matter formation and carbon stabilization, potentially enhancing soil carbon stores. The objective of this study was to address the following questions: 1) Will the dominant mycorrhizal type change with disturbance? 2) Does extensive tree mortality change the amount of carbon and nitrogen stored in forest floors and mineral soils? I sampled soil and conducted vegetation surveys at 80 lodgepole pine-dominated sites across west-central Alberta, split by disturbance severity (forests with >70% lodgepole pine basal area killed by MPB versus intact forest) and soil texture (coarse versus fine). I used density fractionation to separate soils into mineral-associated organic matter (MAOM) and particulate organic matter (POM) pools. I explored whether disturbance, mycorrhizal type, soil texture, and sampling depth affected carbon and nitrogen concentrations in these pools. There was a pronounced shift in mycorrhizal community composition from EM to AM dominance following MPB- induced forest transformations. However, overall carbon and nitrogen concentrations in bulk mineral soil, and carbon and nitrogen stocks in forest floors, remained largely unaffected. In addition, I confirmed that carbon and nitrogen storage are strongly dependent on soil texture and depth. Though there were no changes in soil carbon concentrations in the bulk soil, carbon in the MAOM fraction was relatively higher in the disturbed than intact sites. Greater carbon and nitrogen allocation into the MAOM pools is consistent with emerging hypotheses on the importance of AM vegetation to long-term carbon storage in soils. Taken together, these patterns in carbon storage may point to the resiliency of these soils, supported by soil organic matter interactions with the mineral matrix and potentially the buffering effects from the increase of AM fungi and their unique nutrient dynamics. The findings from this study may enhance our understanding of soil processes, offering opportunities to optimize soil carbon stocks and ecosystem services in recovering boreal forests.
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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 | 0,001 | 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) | 0,000 | 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 ».