Self‐pruning in tree crowns is influenced by functional strategies and neighbourhood interactions
Notice bibliographique
Résumé
Abstract As canopy closure imposes light limitation in forests, the dieback of trees' lower branches, known as self‐pruning, defines their live crown base and shapes the structure and function of entire stands. Self‐pruning is often thought to occur after shading causes individual branches to transition from carbon sources to sinks. Under this assumption, we would expect resource‐conservative and shade‐tolerant species to initiate self‐pruning under deeper shade because their branches require less light to maintain a positive carbon balance. However, this pattern may be complicated by ‘correlative inhibition,’ which may cause plants to preferentially allocate resources towards sunlit branches. Consistent with this idea, we predicted that within species, trees with sunlit tops would initiate self‐pruning at a higher light threshold. Lastly, we predicted that community‐level diversity in self‐pruning strategies would correlate with productivity and total crown volume. We tested these predictions in an experiment where 12 temperate tree species were planted in plots of varying diversity and composition. We measured crown dimensions and position as well as the fraction of light reaching the crown base (denoted L base ), which we took as an estimate of the light threshold of self‐pruning. As predicted, shade‐tolerant and resource‐conservative species self‐pruned at a deeper level of shade (lower L base ). Within species, trees generally had higher L base when they had more light at the crown top, suggestive of correlative inhibition. With respect to their neighbours' traits, though, conservative and acquisitive species showed contrary patterns of plasticity: conservative species had lower L base around conservative neighbours, and acquisitive species around acquisitive neighbours. As predicted, plots with a greater diversity of L base had greater basal area and crown volume. Using simulations, we showed that adjustment of crown depth from monocultures to mixtures strengthened the relationship between diversity of L base and crown volume, primarily due to competitive release that benefited acquisitive species. We provide evidence that self‐pruning strategies are intimately connected to resource acquisition strategies and propose that L base may serve as a functional trait to quantify them. Our results reinforce the role of tree architectural diversity in the functioning of light‐limited forests. Read the free Plain Language Summary for this article on the Journal blog.
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Comment cette classification a été obtenuedéplier
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 | 0,000 | 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) | 0,004 | 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 tête enseignante, 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 ».