Bioindicator plants of soil quality in an agro-ecological zone in Ahoué (Southern Ivory Coast): Application to peanut cultivation

In a context of soil degradation, this study examines the relationship between floristic composition and soil properties in the agro-ecological zone of Ahoué, southern Côte d'Ivoire, using a methodological approach combining the Indicator Value Index (IndVal), multivariate analysis (heatmap and hierarchical clustering) and environmental gradient mapping. The main objective is to identify and characterize bioindicator plant species of soil quality in this area. Our results highlight significant and robust correlations between some species and specific edaphic conditions. Mallotus oppositifolius and Centrosema pubescens were found to be strongly associated with soils characterized by high organic matter (OM) and high cation exchange capacity (CEC), suggesting favorable fertility conditions. Conversely, Xylopia aethiopica and Usteria guineensis were identified as indicators of acidic and potentially degraded soils, with low CEC and lower nutrient retention, which could negatively impact the growth of sensitive crops. Multivariate analysis confirmed the high spatial variability of edaphic parameters along the topographic gradient, highlighting the heterogeneity of crop growth conditions within the study area. These results highlight the importance of plant bioindicators for characterizing soils and anticipating their evolution under the effect of pedogenetic processes and anthropogenic disturbances. The integration of spatial models and species functional diversity would help refine ecological diagnoses and optimize soil conservation and sustainable management strategies.