The structural analysis was carried out in Carajás and Marabá regions, South of State of Pará. The sampling plots of the forest inventory were divided in two levels: I) main sample plot with 20m x 200m for all trees with dbh>20cm and, II) sub-sample plot with 10m x 10m for all trees with 5cm ≤ DAP ≤ 20cm at the beginning and at the end of the main sample. All trees of the level II were considered as natural regeneration of the studied forest. In Carajás were set up 35 (thirty five) sample plots and 22 (twenty two) in Marabá region. The Shanon-Weaver diversity indexes were 3.66 for Marabá and 3.71 for Carajás region. The observed data were better fitted by the following hypsometric function (relationship between height and dbh): The dominances averaged 131.92 and 127.85 trees/ha for Carajás and Marabá, respectively. The basal areas averaged 15.41 and 17.35 m2/ha for Carajás and Marabá. The density functions of Meyer which best fitted the observed data were Fi= e(9.56330614 - 0.07139847d) for Carajás and Fi =e(8.96125691 - 0.06937877d) for Marabá. For both regions about 36% of the inventoried species have some economical market value.
Phytosociological study; forest inventory; forest management