Study area and forest inventory
The present study was carried out in mixed species stands located in the Sudano-Guinean ecological transition zone in Republic of Benin. The transition zone is characterized by a unimodal rainfall regime (one rainy season and one dry season of unequal durations), with an annual rainfall of 1200 mm, and average daily temperature of 28°C (Adomou, 2005). There is little or no variation in the type of soil, which is mainly ferruginous. The plantations were established in the Bellefoungou Forest Reserve (9°46’40” - 9°49’00” N and 1°42’00” - 1°45’00” E), to restore the forest cover in degraded areas subject to high anthropogenic pressure. They were initially established using exotic species (Tectona grandis L., Gmelina arborea Roxb.), but did not receive silvicultural and management interventions, hence, evolved into mixed species stands with the occurrence of many other native species including Vitellaria paradoxa (Gaertn C. F.), Isoberlinia doka Craib & Stapf, Pterocarpus erinaceus Poir. Like most tropical sudanian vegetation, these stands exhibit a well-structured, multi-storey woody vegetation, consisting of sub-canopy, canopy and emergent tree species. The most dominant species in these stands is