Do the Igapó Trees Species are Exclusive to this Phytophysiognomy? Or Geographic Patterns of Tree Taxa in the Igapó Forest – Negro River – Brazilian Amazon

Abstract

This chapter intents to contribute to the knowledge of the geographic distribution of tree taxa in Brazilian igapo forest and presents an analysis of the distribution of tropical tree species from periodic flooded areas, focusing on the description and interpretation of the patterns of local, regional and global. We used 19 floristic and phytosociological works carried out in periodically flooded forests of the Rio Negro basin, Brazilian Amazon, and classified them according to the occurrence area of tree species using the phytogeography patterns established by Prance (1977). Considering the different possibilities of occurrence of a taxon in the Amazon biome, we defined three possible tree species geographic patterns: AA – ample amazon; FP – floodplain area; and BW – black water. For each taxon we calculated the frequency of occurrence. For each phytogeographic pattern we investigated the occurrence of each taxon in other formations out of the Amazon forest, according to the five biomes by IBGE classification: Cerrado (CE), Caatinga (CA), Pantanal (PA), Mata Atlântica (MA) and Pampa (PP). In all, 19 surveys were selected; the specific richness of at least 636 woody taxa was recognized. Of these, 380 species are duly determined and belong to 211 genera and 62 families. We checked 231 species with wide distribution on the Amazon (AA), 65 occur only on floodplain (FP), 61 occur only near black water river (BW), 7 are restricted to one formation on Amazon and 16 species are not registered on Species Link site. The majority of the species BW are considered rare (59%) and only 12 species (19.7%) occur in other Brazilian biome. We observed the same with floodplain species (FP), only 12.3% also occur in other Brazilian biome. In general, the most constant/moderately frequent species in the igapo forest showed large geographic amplitude occurring in other Brazilian biomes. A great proportions of them also occurred in cerrado (CE), followed by Atlantic rain forest (MA). The fact that about 37.6% of all species occurred also in other formations, 43.1 % of genera and 69.4 % of families in igapo forest also occur out of Amazon forest.