The fruit of the açaizeiro (Euterpe oleracea Mart.) Has been gaining prominence in the food market and with that intensified the interventions in the forests of floodplains with massifs of this species. In this study, we evaluated the changes occurring in a seventeen-year interval in the floristic diversity in native açaizais destined for fruit production. The study was developed in 35 açaizais located in the region of the north arm of the Amazonian estuary. Two floristic inventories were carried out in the same açaizal, one in 2001 and another in 2018. In each inventory, 20 m x 50 m parcels were marked, where all individuals with CAP≥15 cm were identified and measured. We found in the 35 plots evaluated in 2001, 109 species, 80 genera, 35 families out of 3311 individuals. Of this total, 1759 individuals of E. oleracea and 1541 individuals of other species, 11 individuals were not identified. In 2018, 70 species, 57 genera and 29 families of a total of 2706 individuals were found in these same açaizal. Of this total, 2136 individuals of E. oleracea and 562 individuals of other species, 8 individuals were not identified. The average number of adult scions of açai trees per plot was 36 in 2001 and 79 in 2018. The species richness decreased by 36% and the Shannon index (H ') decreased from 2.40 nats/ind. in 2001 to 1.26 nats/ind. in 2018, observing a reduction of 48,75% of the floristic diversity in the studied açaizals. The riverside of the Amazonian estuary do not follow the recommendations of the management of minimum impact and develop different strategies to increase the production of the açaizal. The results indicate a homogenization of the native açaizais due to the favoring of the açaizeiro, palm tree of greater economic interest in the region of the Amazonian estuary. The evaluated açaizals show a tendency to the floristic impoverishment of the várzea forests of the amazonian estuary
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