Age and spatial structures of a population of Calophyllum brasiliense (Clusiaceae) were studied in a 3600 m2 area of a swamp forest in Brotas, São Paulo State. During the first census, 1658 plants were tagged and after one year this number increased to 1706. Age structure did not change over the period of study, with a greater number of seedlings (individuals £ 0.2 m) and juveniles (> 0.2 - 2 m) and a smaller number of subadults ( > 2 - 10 m) and adults ( > 10 m). Seedling (29.7%) and juvenile (5.3%) mortality was caused, mainly, by soil erosion and deposition during the rainy season, because the plants were buried. Subadult (0.7%) and adult (0%) mortality was very low. A large number of new seedlings was concentrated in the lower parts of the study site and in soil depressions where the water carried seeds which were deposited and germinated. Recruitment rate for seedlings was high (48.1%), while for juvenile (7.3%), subadult (1.9%) and adult (0%) were much lower. Plants of all classes, from seedlings to adults, presented a clustered distribution, due to the topography of the study site, which facilitates seed accumulation, and to a higher number of seeds under the canopy of reproductive individuals. Fruit dispersion by bats or water, seed survival under hypoxic conditions, seedling tolerance to waterlogging, age structure with a significant predominance of seedlings and population growth explain why C. brasiliense is the most abundant species in the forest studied and also in other similar forests in Southeastern Brazil.
Swamp forest; population dynamics; demography; Calophyllum brasiliense
