Dynamique spatio-temporelle de la forêt du Mayombe (2000–2025) à Mvouti (Kouilou, République du Congo) : Une analyse par télédétection et modélisation CA-Markov à l'horizon 2050
DOI :
https://doi.org/10.59228/rcst.026.v5.i4.361Mots-clés :
Mayombe, télédétection, modélisation, Random Forest, déforestation, CA-Markov, régime foncier, REDD+, fragmentation forestièreRésumé
Le district de Mvouti, situé dans le département du Kouilou (République du Congo), abrite une partie essentielle du massif forestier du Mayombe, qui englobe la réserve de biosphère de Dimonika (136 000 ha, UNESCO-MAB 1988). Cette réserve a été sélectionnée car elle représente un hotspot de biodiversité soumis à de fortes pressions anthropiques liées à l'orpaillage artisanal et à l'exploitation forestière. À partir de six composites d'images Landsat (2000–2025) classés via l'algorithme Random Forest sur Google Earth Engine, cet article quantifie la dynamique spatio-temporelle du couvert forestier, analyse la fragmentation du massif et simule trois trajectoires prospectives à l'horizon 2050 à l'aide de la modélisation CA-Markov. Avec une précision globale de classification de 90,6 % (κ moyen = 0,883), la forêt dense a perdu 32 106 ha (soit 9,1 % du couvert initial) entre 2000 et 2025. Le taux moyen de déforestation est estimé à 0,37 %/an, soit trois à quatre fois plus que la moyenne nationale congolaise. La désagrégation par statut foncier révèle des dynamiques contrastées : les zones situées hors des concessions forestières ont culminé à 2,27 %/an entre 2015 et 2020, tandis que les concessions aménagées (UAF) au sein de la zone tampon de la réserve ont maintenu des taux nettement inférieurs. La fragmentation s'est fortement intensifiée (le nombre de fragments est passé de 442 à 6 189 ; MESH : −21,5 %). Selon le scénario de gouvernance intégrée (SC3, conforme à la loi n° 33-2020 et à la Contribution Déterminée au niveau National [CDN]), les pertes d'ici 2050 se limitaient à 14 255 ha, contre 45 634 ha en cas de scénario de défaillance de la gouvernance (SC2). Ces résultats fournissent une base de référence quantitative directement applicable pour la révision du Plan d'Affectation des Terres du Kouilou et la mise à jour des rapports de la CDN congolaise.
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