VEGETATION STRUCTURE OF A CERRADAO, AND THE REGIONAL HETEROGENEITY OF THE CERRADO IN MARANHAO, BRAZIL

The structure of a Cerradao in northeastern Maranhao was evaluated aiming to contribute to the characterization of the vegetation heterogeneity in this state. The Point-Centered Quarter method was used for sampling 399 points in three parallel transects, systematically placed each 200m. The starting point of the first transect was randomized. The minimum inclusion criterion was 1 cm diameter at soil level. The 1596 sampled individuals represented 69 species and 32 families. Plathymenia reticulata (Candeia) was the species with the highest Importance Value Index (IVI), differing from other regions in the state. Diversity (H' = 3.31) and equability (J = 0.78) were high, and within the known range for Maranhao cerrados. The floristic comparison among seven cerrado areas in this state showed high heterogeneity and low similarity. The nearest areas showed the highest floristic similarity only in the analyses with species abundance values.