Assessing dynamics and productivity of tropical natural forest using permanent plots: case study of mounts kouffè and warimaro forests reserve

The dynamic and productivity of natural reserves in Benin were assessed in the Mounts Kouffè and Wari Maro forest reserves on the basis of sixty circular permanents plots of 1000 m2 size each installed in 2006. The factorial correspondences analysis of the based on a matrix of 60 records and 81species. Four different plants community were discriminated: - dry woodland of Diospyros mespiliformis and Anogeïssus leïocarpa - woodland of Pterocarpus erinaceus and Isoberlinia doka - Wooded savanna of Vitellaria paradoxa and Burkea africana - Shrub savanna of Vitellaria paradoxa ans Isoberlinia doka The specific richness of individualized plant communities varies between 42 and 75 species. The Shannon index values calculated (dbh≥10cm) ranged between 1.25 and 4.66 bits; those of Pielou evenness ranged between 0.24 and 0.87. The diameter size classes distribution is best adjusted to Weibul three parameter function and showed a left skewed distribution. Trees basal area decreased by 0.80 m²/ha/year for the dry woodland and 0.25 m²/ha/year for the woodland while the one of wooded and shrub savanna increased by 0.50 m²/ha/year. The density of trees decreased by 120 trees/ha for dry woodland and by 108 trees/ha for woodland over the last five years. The diameter of individuals of average basal area has increased by 2.1 cm for dry woodland. 3.95cm for woodland. 2.8cm for Wooded savanna and 3.09cm for shrub savanna. The minimum exploitable diameter (MED) of 45cm allowed for 50% of Anogeïssus leïocarpa and Isoberlinia doka basal area reconstitution while this MED allowed for 75% of Diospyros mespiliformis reconstitution.