Estrutura da vegetação sob influência de águas pretas e brancas no baixo Rio Negro, AM, Brasil

Abstract

The objective of this study was to characterize the floristic composition and structural parameters of the arboreal vegetation of an area periodically flooded with either white or black water, depending on the water level of the Solimões River or the Negro River, respectively, in the region of the confluence of the Ariaú channel with the Negro river. For this purpose, two plots of 0.5ha each were installed in order to sample the vegetation with PAP≥ 30cm. Data were analyzed using Fitopac 2.10 software. The area was compared with 17 other studies carried out in floodplains and igapós geographically close to the study area, through a DCA, Cluster clustering (using PC-ORD 6.0) and Jaccard Similarity Index. A total of 572 individuals, 58 species and 26 families were recorded and H’= 2.98. The study area is composed of non-pioneer species, dispersed and pollinated by animals with medium to high wood density. Triplaris surinamensis and Handroanthus barbatus were the most frequent species, as well as those with the highest importance value, followed by Nectandra cuneatocordata and Luehea paniculata. Considering the ranking of the richest families, they confer floristic characteristics to the area more similar to the igapó, but the species with the highest importance value are more common in floodplain areas. According to the clustering and ordering analysis (DCA), this area is floristically closer to studies carried out in floodplain than in igapó. Given the set of results observed, it can be concluded that, although geographically closer to the main channel of the Rio Negro, the influence of the muddy waters of the Solimões river influences the floristic composition, resulting in a greater similarity with the floodplain, but without a distinction abrupt between the phytophysiognomies.