Estimation of cultivable areas for Irvingia gabonensis and I. wombolu (Irvingiaceae) in Dahomey-Gap (West Africa)

Abstract

Cultivation of priority plant species ensures their sustainable management. African bush mango trees (Irvingia gabonensis and I. wombolu) are the most exploited Irvingiaceae species. Experts disagree on the status of these very similar taxa, as taste remains the only character by which they can be distinguished in the field. We combined occurrences and environment data in ecological niche models to assess suitable areas for the two species. Irvingia gabonensis presented a wider occurrence area due to cultivation across contrasting ecological areas. Irvingia wombolu does not appear to be cultivated and only occurred in southwestern Togo. These differences in range is likely determined by phenological limitations of I. wombolu, reinforced by differences in local management systems, thus confirming the failure of market development to impact useful plant species’ conservation significantly. Highly suitable areas for I. wombolu were in the Volta Forest, where I. gabonensis saw low suitability, while out of this inverse situation was observed, as regard environmental suitability. These differences are significant, implying different ecological adaptation. However, anthropogenic influences, related to domestication history, are also important. Therefore, updated genetic investigations and field trials in contrasting ecological areas are required for understanding the origin of differences between these two forms.