As florestas de Belo Monte na grande curva do rio Xingu, Amazônia Oriental

Abstract

In order to characterize the forests of the Belo Monte region at the ‘Volta Grande’ of the Xingu River, Brazil, a floristic, phytosociological, structural and ethno-botanical analysis was undertaken in forested areas of Altamira, Anapu, Senador José Porfírio, and Vitória do Xingu, in the Lower and Middle Xingu River regions of Pará. In the four most common forest formations (dense broadleaf forest, broadleaf flood forest, open broadleaf forest with palms, and broadleaf forest with lianas and palms) study plots were laid out that covered a total area of 24.3 ha. Surveys included individuals in three diameter size classes: DBH ≥ 5, 10, and 30 cm. A total of 13.790 individual plants was recorded, comprising 662 species distributed in 65 botanical families. In comparing the forest types, it is concluded that the dense broadleaf forest is the most species rich (433 spp.), followed by the open broadleaf forest with lianas and palms (264 spp.), the broadleaf flood forest (203 spp.), and the open broadleaf forest with palms (140 spp.). In relation to rare species, the dense broadleaf forest showed the greatest number (141 spp.), in contrast to the open broadleaf forest with palms that showed the least (63 spp.). Caesalpiniaceae was the family that had the greatest indices of economic importance (IVIF) and of total coverage (IVCF) in all of the studied forest types except for the open broadleaf forest with lianas and palms (Lecythidaceae). Alexa grandiflora and Voucapoua americana were the species with the greatest indices (economic importance and total coverage) in all the studied Forest formations, except in the broadleaf flood forest (Pterocarpus amazonicus and Molia luscens). It is estimated that these analyzed ecosystems have a combined area of 92,68 km² in the study area. A total abundance of 403,069,870 trees with DBH ≥ 10 cm is estimated, with a total wood volume of 196,276,924 m³ and a live aerial biomass of 198,503,191 metric tons. Forest species of great interest for floral conservation programs were identified, such as the practically extinct Amazon cinnamon tree ‘pau cravo’ (Dicypellium caryophyllatum), a member of the Lauraceae that is much sought-after by the perfume industry, and another rarely found species (Sagotia brachysepala), a member of the Euphorbiaceae with a very restricted geographical distribution