The goal of the study is to determine the vegetal composition and structure based on mature trees in the Masako Forest Reserve. A transect was installed in a mono-dominant forest
with Gilbertiodendron dewevrei at 5 km from the guest house. For transect of 2,100 m, we placed a 500 m perpendicular line to the survey to a plot of 2,500 square meters in a G. dewevrei forest. An inventory was carried out in an area of 3 ha, consisting of 12 plots of 50 × 50 m. All trees with a diameter equal or greater than 30 cm were inventoried, and divided into eight size classes according to their dbh (diameter at breast height) dimension: ˂40 cm; 40 to 49.9 cm; 50 to 59.9 cm; 60 to 69.9 cm, 70 to 79.9 cm; 80 to 89.9 cm; 90 to 99.9 cm and ≥100 cm. To facilitate the inventory, the survey plots were divided in two subplots of 1,250 m2. For the entire forest, we found an overall density of 86.3 stems per hectare of which 63.3 stems/ha belonged to G. dewevrei. We also found that the basal area for an individual tree was on average 29.5 mfor
the entire forest, and 24.2 m2.ha-1for G. dewevrei.