A phytosociological survey was carried out in the Grota Funda Municipal Park, Atibaia Municipality, São Paulo State (45º45' - 46º45'W and 23º10' - 23º15'S). The region is mountainous, occurring from 900 to 1400 meters above sea level. A total of 42 quadrats, each 10 x 10m, were plotted along an altitudinal gradient. In each sample, all trees with perimeter > 15cm at breast height were recorded. The study was done from April 1987 to November 1988. In the phytosociological survey, 1076 individuals were recorded, belonging to 52 families, 92 genera and 134 species. Phytosociological parameters of frequency (absolute and relative), density (absolute and relative), dominance (absolute and relative), importance value index and cover index are presented for all species. The results show that the most important families are Myrtaceae, Lauraceae, Euphorbiaceae, Apocynaceae and Mimosaceae and the most important species are Machaerium nictitans, Aspidosperma olivaceum, Anadenanthera colubrina, Sebastiania edwalliana, Guapira opposita and Styrax pohlii. The semideciduous, moutain forest is unique and represents a kind of forest that occurs only in regions above 1000m, with floristic and phytosociological particularities.
phytosociology; moutain forests, semideciduous