Pterocarpus erinaceus is a native tree species of the Guineo-Sudanian and Sudano-Sahelian zones where natural stands are under constant pressure and heavily exploited for timber, animal feeding and others uses. A part from the overexploitation, climate change could also become a serious threat to the species natural distribution. For that purposes, this study aims to assess the vulnerability of P. erinaceus potential niche to climate change within its natural distribution area in West Africa. Niche predictions are based on 6,981 natural occurrence of the species and 19 global bioclimatic variables available through WorldClim. The future niche of the species is predicted according to three concentration pathways (RCPs 2.6, 4.5 and 8.5) of BC model for 2050 and 2070, thanks to Maxent software. P. erinaceus is currently reported from Senegal to Cameroon. Its potential niche covers the Sudano-Sahelian zone and the Dahomey gap on approximately 17.42% of the total area of these countries. In general, the niche of the species is not sensitive to climate change, regardless of the climate scenario and the year. Compared to its initial niche, the niche of the species will increase from 22.33% to 43.61% in 2050 and from 27.12% to 53.61% in 2070. However, this ecological expansion observed mainly in the Gulf of Guinea, will be associated with a considerable decrease in the Sahel and central Nigeria. This study shows the importance of promoting the development of innovative silvicultural strategies for the extension and restoration of natural stands of P. erinaceus in order to meet sustainably the timber needs of the West African region. It helps also to strengthening the roles of natural forests in providing ecosystem services and mitigating climate change effects.

Pterocarpus erinaceus Poir. (Fabaceae), also called Vène or West African rosewood, is a multipurpose endemic forest species of Sahelo-Sudanian and Sudano-Guinean savannas and forests of West Africa. In Togo, the species is overexploited, which dangerously hinders its survival. The need and emergency of restoring declining stands, using seeds, or propagating material suggests an assessment of its morphological variability. The purpose of this study is to identify the discriminating morphological descriptors, allowing us to describe and also to characterize the species. Five provenances distributed over the whole geographical distribution area in Togo were evaluated for leaf (7 descriptors), fruit (4 descriptors), and seed (4 descriptors) traits. The coefficient of variation (CV) and the principal component analysis (PCA) are used to assess the variability among tree populations. Results show that the discriminating morphological descriptors for P. erinaceus in Togo are the width of the leaf and the terminal leaflet, the length and the width of the fruit, and length and the weight of the seed. These six main relevant variables allow us to discriminate three morphological groups of P. erinaceus population.

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Lawsonia inermis L. ou henné, est extrêmement réputé pour ses vertus cosmétiques, tinctoriales mais aussi médicinales. Cultivé dans les régions tropicales et subtropicales, le mode préférentiel dans les plantations industrielles des principales régions exportatrices du Moyen Orient, d'Asie et d'Afrique, est le semis. Cependant plusieurs contraintes limitant sa germination et sa multiplication à grande échelle au Togo ont été rapportées. Les graines entourées d'une coque dure et résistante germent difficilement au-delà de 20% et ne sont conservables qu'au plus trois mois. Cette étude vise la vulgarisation de la culture de cette espèce à valeur ajoutée au Togo. L'évaluation des effets de facteurs externes et endogènes sur la germination montre que la lumière est indispensable pour la germination. Les graines réagissent positivement à l'allongement de la photopériode de 0% à obscurité continue à 94% pour 16 h de lumière. L'enfouissement dans le substrat réduit drastiquement ce taux dès 5 mm de profondeur. Conservées à 25±2 °C sur huit mois en boîtes plastiques à l'obscurité, les graines révèlent une excellente capacité germinative dépassant les 93%. In vitro, elles germent à plus de 90% et les jeunes plants présentent une croissance régulière. Les conditions optimales de germination ainsi établies permettront donc la vulgarisation de la culture du henné.

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.