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