Composition and Floristic Diversity of the Vegetation in Zuénoula Department, Central-Western Côte D’Ivoire

Abstract

Background: Despite their ecological importance, the savanna-forest transition zone of Côte d'Ivoire is facing increasing human pressures that threaten its botanical heritage. This study addresses the urgent need for updated floristic data to guide conservation efforts in the said zone. Aims: The present study aims to analyze the composition and floristic diversity of the Zuénoula department. Study Location and Duration: The study was conducted in 3 sub-prefectures of the Zuénoula department (Central-West Côte d'Ivoire), from April 2020 to October 2021. Methodology: The study was conducted in the department of Zuénoula (7°10’–7°45’ N; 5°43’–6°26’ W), characterized by a mosaic of wooded savannas and dense forests. The floristic inventories combined plot-based surveys and itinerant inventories in primary (undisturbed for >30 years) and secondary (<30 years) formations. In total, 60 permanent plots of 2,500 m² were randomly established across six localities. Within each formation type, the plots were stratified according to a topographic gradient (lower slope, mid-slope, and summit) in order to capture environmental heterogeneity. Itinerant inventories were carried out to record species outside the plots. Taxonomic identification was performed using regional reference floras and laboratory analyses. The data were then processed to determine the composition and floristic diversity of the vegetation. Results: In total, 332 plant species distributed across 250 genera and 80 families were recorded, with an abundance of Fabaceae (51 species), Poaceae (31 species), and Malvaceae (22 species). Secondary plant formations were found to be more diverse in genera and species than primary plant formations, although both formations are floristically heterogeneous (47.22%). The dominant biological types were Therophytes (24.4%), Microphanerophytes (20.18%), and Mesophanerophytes (12.65%), while herbaceous plants were the most abundant morphological type (43.98%). Chorologically, the species were mostly from intertropical Africa and the Guineo-Congolian region, with 130 and 110 species respectively. The inventoried flora also included species with special status, including 3 listed on the Red List of the International Union for Conservation of Nature (IUCN), 3 endemic to Côte d’Ivoire, and 34 introduced. Vegetation of Zuénoula department was dominated by species characteristic of the potential major flora (86 species), the most important of which were Annona senegalensis, Blighia sapida, and Fleuggea virosa. Conclusion: These results show a rich flora but influenced by human activities, hence the need to implement appropriate management and conservation measures.