Pterocarpus erinaceus Poir (Fabaceae) is an endemic, highly exploited and threatened plant species in arid and semi-arid zones of West Africa. This study was conducted at the sub-regional level across three countries, namely Burkina Faso, Niger and Togo. These countries represent a spatial ecological gradient of P. erinaceus distribution to collect information on population structure and silviculture operating standards that could guide the industry, ensure species regeneration and establish appropriate management strategies for the species. Data were collected in P. erinaceus populations by means of forest inventories. Results showed that the average tree density was 1.17 ± 0.75 trees/ha in the Sahelian zone, 49.20 ± 63.2 trees/ha in the Sudanian zone and 110.9 ± 1.15 trees/ha in the Guinean zone. The average stem diameter values were 26.63 ± 7.89 cm (Guinean zone), 29.02 ± 15.44 cm (Sudanian zone) and 49.63 ± 19.44 cm (Sahelian) with noticeable variability (CV = 53.6%). Significant differences for these parameters were noted between the zones (P < 0.001). The average total height in the populations of the Sudanian zone (9.51 ± 2.75 m) were significantly less (P < 0.001) than in the other two zones (10.18 ± 2.27 m for the Sahelian zone and 14.16 ± 2.88 m for the Guinean zone). The merchantable heights were between 4.08 ± 1.35 m (Sahelian zone) and 3.63 ± 2.63 m (Guinean zone) and varied significantly from one zone to another (P < 0.001). The distribution of trees in diameter classes varied depending on the climate zone: modal distribution with most classes ranging from 30–65 cm in the Sahelian zone and 15–45 cm in the Sudanian zone and an “L” model distribution in the Guinean zone (most classes ranging between 10 and 25 cm), while the distribution of height classes showed a modal form for all climate zones. Two minimum diameters of exploitation (MDEs) could be determined: 35 cm for the Guinean and Sudanian zones (P = 316.6% and P = 53.4%, respectively) and 65 cm for the Sahelian zone (P = 111.9%) for a rotation period estimated at 20 years for all the climate zones.

Les îlots de forêts semi-décidues de la réserve de faune de Togodo constituent l’un des rares écosystèmes forestiers dans le paysage dénudé et fortement anthropisé de la plaine côtière du Sud Togo. L’analyse structurale de ces îlots forestiers a été réalisée au travers d’inventaires forestiers conduits dans 45 placettes. Dans chaque placette (625 m² de superficie), chaque individu ligneux (souche autonome dont le dbh ≥ 10 cm) a fait l’objet d’une détermination botanique et de mesure de ses caractéristiques dendrométriques. Les données recueillies ont permis d’établir un diagnostic sur l’état de conservation des espèces végétales de cette aire protégée. Au total, 73 espèces ligneuses ont été recensées avec une densité moyenne évaluée à 955 ± 303,1 N/ha et la surface terrière égale à 38,9 ± 18,9 m²/ha. La densité moyenne de la régénération a été estimée à 6465 N/ha. La répartition des espèces par mode de régénération montre que l’essentiel des espèces se régénère préférentiellement par semis (84,1 %), faiblement par rejets de souches (12,4 %) et rarement par drageonnage (3,5 %). La courbe exponentielle décroissante que révèle la distribution des individus en classes de diamètre indique que ces formations forestières ont subi une ou plusieurs dégradations et sont actuellement en cours de reconstitution, mais regorgent encore d’un grand potentiel en ressources forestières ligneuses. Les informations obtenues à travers cette étude constituent d’importantes bases techniques pour tester les indicateurs écologiques de gestion durable des forêts et fournissent des informations sur la mise en œuvre des directives de gestion pour la sauvegarde de cette aire protégée.

Pterocarpus erinaceus is an endemic and threatened plant species in arid and semiarid zones of West Africa and is highly exploited for timber, animal feeding, and various medicinal uses. The species is currently native to the Guinean forest-savannah mosaic ecoregion and reported from Senegal to Cameroon. The values of the main characteristics of the P. erinaceus forest stands (density, average diameter, average height and average stem height) vary significantly (P < 10−3) from the Guinean zone to the Sahelian zone. It has high technological performance and can be classified as heavy and very hard wood with a density of the order of 0.80 ± 0.07 g/cm3 and an average hardness of 12 ± 3.7 g/cm3. The species is the subject of large-scale international traffic between West Africa and Asia, which is by far the greatest threat to the species. The various uses induce repeated mutilation and increase pressures on the species resulting in a significant reduction in its natural populations. In response to this situation, measures are proposed, including large-scale plant production strategies, the definition of minimum felling diameters, policy measures, etc., to meet the restoration needs of natural stands of P. erinaceus and the fight against climate change.