Distribuição, abundância e fenologia reprodutiva de palmeiras em uma floresta de terra firme da Amazônia Central

Abstract

Palms are widely distributed in tropical rain forests and have great ecological and economical importance. The natural heterogeneity of forests produce a great variety of micro-environments that can reflect the niches of species. In this study we showed that a group of nine palms is influenced by the variation of the structural components of a well-drained (Terra firme) forest at Ducke Reserve, Manaus. The species were Attalea attaleoides (Barb. Rodr.) Wess. Boer., A. maripa Mart., Euterpe precatoria Mart., Geonoma aspidiifolia Spruce, Iriartella setigera (Mart.) H.Wendl., Oenocarpus bacaba Mart, O. bataua Mart., O. minor Mart., and Socratea exorrhiza (Mart.) H. Wendl. We recorded all the seedlings and adults of these palms in 40 plots of 50 x 50 m randomly distributed in 12 km2. In the same plots we also registered forest canopy opening, leaf litter depth, logs on the ground, altitude, plot s distance from the nearest stream (Igarapé), number of forest trees (not palms) with DBH between 10 and 30 cm and with DBH above 30cm. The palms reproductive behaviour was also observed, at every other two months, from August/2007 to October/2008. Abundance data of seedlings and adults of flowering and fruiting trees were used as dependent variables in statistical models to evaluate relationships with changes in the forest heterogeneity. Vectors resulting from the non-metric multidimensional scaling ordination (NMDS) were used in models to evaluate how changes in composition of the nine species of flowering and fruiting palms were influenced by changes in the forest heterogeneity. Seedlings of Oenocarpus bacaba and O. minor were more abundant in shaded areas of the forest. Seedlings of Oenocarpus minor and O. bacaba were more abundant in areas with minor amount of logs on the ground. Total abundance of seedlings was higher in areas with increased abundance of trees. Considering the reproductive behavior, higher abundances of flowering individuals of Attalea attaleoides were found in more elevated areas and areas with increased abundance of logs while flowering of Iriartella setigera were more abundant in areas with higher leaf litter depth. The results indicate that the distribution, abundance and reproductive behavior of palms in Central Amazonia are influenced by the landscape which is produced by changes in the spatial distribution of the structural components of the forest.