Florística e estrutura de um trecho de Floresta Ombrófila Densa Atlantica Submontana no Parque Estadual da Serra do Mar, em Ubatuba/SP, Brasil

this work describes the tree community structure and composition in a 1 ha plot of undisturbed atlantic forest located at the north coast (s 23° 21' 59.8" - w 45° 05' 02.8") of s？o paulo state and relates its floristic composition in a regional context. we sampled all stems with diameter at breast height (dbh) > 4.8 cm in 100 contiguous 10 × 10 m plots. we found 1881 individuals distributed in 206 species, 102 genera and 48 families. 1578 stems were trees (83.9%), 237 palms (12.6%), eight ferns (0.42%) and 58 standing dead trees (3.08%). myrtaceae (43), rubiaceae (18), lauraceae (16), and fabaceae (13) were the families with the greatest number of species, respectively. rubiaceae, myrtaceae, arecaceae, and sapotaceae had the greatest number of individuals, respectively, summing 946 stems (50.29%). euterpe edulis mart. had the highest importance value (iv) and stem density (9.5%). we found two new species and two other species had their first record in s？o paulo state. the species richness (206) and diversity (h' = 4.48 nats.indivíduo-1) are among the highest ever recorded in brazilian forests.