Ontogenic dynamics of phenotypic diversity in savanna mahogany (Khaya senegalensis) across three sites in Côte d’Ivoire

Abstract

This study aimed to assess the morphological variability of savanna mahogany ( Khaya senegalensis ) through an ontogenic approach across three natural stands Kouassi-N’Dawa, Koumokro, and Pouniakele subjected to contrasting environmental conditions in Côte d’Ivoire. On each site, eleven morphological parameters were measured on trees distributed among three developmental cohorts: young (5–25 cm in diameter), non-exploitable adult (25–40 cm), and exploitable adult (≥ 40 cm). Analysis of variance revealed significant morphological differentiation among the sites. Trees from Pouniakele, the driest and most disturbed site, exhibited significantly larger mean diameters across all cohorts. In contrast, individuals from Kouassi-N’Dawa (a sacred forest) and Koumokro showed significantly greater foliar dimensions. Hierarchical clustering identified three morphological groups per cohort, while Discriminant Factor Analysis revealed that leaf length (Lel) and leaflet length (Tll) were the most discriminant traits across all developmental stages. Additionally, at the juvenile stage, total height (Tth) and diameter (Dia) were discriminant, whereas at the non-exploitable and exploitable adult stages, petiole length (Ptl) and leaf width (Lew) showed the greatest discriminating power. The persistence of morphological structure across stages suggests consistent patterns of phenotypic differentiation, possibly associated with local conditions, but additional studies are necessary to confirm this hypothesis. Nevertheless, these results provide phenotypic criteria for the selection of superior mother trees and contribute to the conservation and sustainable management of the species’ genetic diversity.