Exploring the effects of forest management on tree diversity, community composition, population structure and carbon stocks in sudanian domain of Senegal, West Africa
Notice bibliographique
Résumé
Human disturbances lead to forest degradation and a drastic reduction in forest area. In Africa, the most affected continent by this phenomenon, selective cutting of trees remains the main forest management strategy. However, the effects of management on biodiversity are insufficiently known, particularly in Africa. We investigated how forest management affects tree species diversity, composition, size structure and carbon biomass of mature and juvenile trees in the sudanian domain of Senegal by comparing unmanaged forests and three types of managed forests, while considering the disturbance level of each stand. We collected floristic data on five and fifteen unmanaged and managed forest stands, respectively. We calculated species richness, the Shannon-Wiener diversity Index (alpha, beta and gamma), as well as carbon stocks of trees for each forest stand. Then we fitted linear models to estimate the differences between forest types for each index. We also analyzed tree size structure and species composition of highly valuable species. In total, 26,009 mature and juvenile trees in 183 species were recorded. Our findings showed that management status and disturbance level affect tree species in different ways and that disturbance level explains a greater proportion of the variation in species diversity than management status. Considering alpha, beta and gamma diversity, we found no significant association between any of these metrics and management status, for either mature or juvenile trees. Disturbance level was only significantly associated with the gamma diversity of mature trees. Species composition of juvenile trees of highly valuable species was significantly associated with both management status and disturbance level, unlike mature tree species composition where the associations were not significant. The distribution of mature tree diameter forms an inverted J-shape for each management category and disturbance level. However, neither the median tree diameter nor the median absolute deviation presented significant differences as a function of management status or disturbance level. For carbon stocks, none of the differences observed by management status and disturbance level are statistically significant. Our findings indicated that forest management in the sudanian zone affects species composition more than diversity and that mature trees respond differently than juvenile trees. Disturbances more than forest management were the underlying process for biodiversity changes both in managed and unmanaged forests. These findings suggest a better protection of unmanaged forests, and also a development of specific conservation action plans for highly valuable species, especially for species that are threatened at national or global levels in order to minimize their risk of local extinction.
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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 | 0,001 | 0,001 |
| 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 ».