Community reorganization in forest understories buried by volcanic tephra
Notice bibliographique
Résumé
Abstract Disturbance is a key factor contributing to community organization. Deposition of tephra (aerially transported volcanic ejecta) is a widespread disturbance of global relevance, but its effects on ecosystems have received limited attention. We studied forest understory community change for 30 yr following tephra deposition from the 1980 eruptions of Mount St. Helens (Washington State). Four old‐growth, subalpine conifer stands had a wide range of initial damage and patterns of community re‐development. We measured understory diversity, structure, and species composition and calculated relationships of plant cover with environment and cover of other plants. Overall, those communities that were altered greatly by tephra tended to converge with time on their pre‐eruption characteristics; however, substantial divergence occurred in some situations. For example , moss cover failed to reach pre‐eruption levels in all stands, whereas importance and diversity of woody plants sometimes greatly exceeded pre‐eruption values. Plant–environment relationships that were significant before the eruption disappeared and did not re‐develop. Smaller plants were more affected by environment than larger ones. Relationships before the eruption and also 30 yr after the eruption were primarily with other plant species, whereas relationships just after the eruption were with tephra depth and factors that modified its impact. Understory plant importance was usually lower beneath a tree canopy than in gaps, but there was little sign of interference from understory growth forms. Post‐eruption soil disturbance usually increased understory plant importance, while woody debris sometimes decreased herb and tree seedling cover. Tephra deposition, which did not immediately kill canopy trees, differed from the disturbances usually studied (e.g., fire, windthrow, bark beetles). Even so, these lessons from our study should be widely applicable: Similar species may respond differently; minor, early environmental differences may induce major, long‐term community change; successional trajectories may diverge from the pre‐disturbance community; and secondary disturbances may modify successional trajectories.
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Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| 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 | 0,001 | 0,000 |
| Communication savante | 0,000 | 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) | 0,002 | 0,002 |
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; les deux têtes enseignantes s’accordent sur ce qui est montré ici.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».