A inundação sazonal e a topografia como indicadoras ambientais da regeneração natural em uma floresta ombrófila densa aluvial na Amazônia Oriental

Abstract

The objective of the research was to evaluate the effects of seasonal flooding and topography in the floristic composition, structure and life form of the natural regeneration in a alluvial dense rain forest in the eastern Amazon. The Environmental Protection Area, Combu Island, were installed four permanent plots of 20 x 20 m, divided into subplots of 1 x 1 m, Between the months of december/2014 to july/2015 all the species and their individuals were identified, quantified, grouped into size categories (CT): CT1= height < 15 cm; CT2= 15,1 < height < 30 cm; CT3= 30,1 < height < 1 m) and subsequently classified according to the life form. The phytosociological parameters calculated were density and relative frequency category of relative size, relative natural regeneration and diversity. Floristic similarity of the plots were performed by the Bray-Curtis index and the dendogram by UPGMA using the statistical Program R 3.1.1. In each plot were set five sticks 1.5 m for the dayle monitoring of the water level in two periods, the rainy season (february to april/2015) and less rainy season (may to july/2015). They were recorded in the rayne season 10,217 individuals, 30 families, 49 genera and 63 species, with an average of flood of 2.88 cm; the less rainy period with 10,124 individuals, 29 families, 46 genera and 59 species did not occur flood in the plots. In both periods, the floristic composition was similar, with no significant difference. Species like Pariana campestris, Anthurius sinuatum, Costus spicatus and Costus arabicus were the most representative, proving to be tailored to the two seasonal periods. The life form tree was dominant in number of species and the herbaceous life form in individuals. The CT1 presented to fewer individuals, unlike CT2. Thus, tide levels did not affect the natural regeneration, indicating species survival between periods. The topographic analysis was performed with the aid of a geodetic GPS Garmim GPS Map, 62s model, by collecting of 20 points of altitude in the four plots. The variation of topography influenced the number of families, genera and species, where the highest plots showed the highest values of families, genera and species. In many species, the life form predominant was tree and herbaceous in individuals. Pariana campestris and Anthurium sinuatum were dominant in all plots, indicating that not influenced by the change in altitude.