Paradox of afforestation in cities in the Brazilian Amazon: An understanding of the composition and floristic similarity of these urban green spaces

Urban green spaces play an important role in improving the quality of life and sustainability in cities and require careful empirical evaluation. This study looked into the contradiction of native species being underrepresented in urban environments in Brazilian Amazon cities, compared to exotic species that have been introduced. It also sought to determine whether there is floristic similarity between the States' urban environments, and if so, what effect geographic distance has on this process; and what implications the States' urbanization gradient has for floristic density of urban afforestation, taking into account the realities of cities infrastructure. A floristic matrix comprising information about the origin of the species and quantitative data was developed using data from scholarly journals and a comprehensive literature study. The floristic consistency of urban vegetation was tested between surveys using dendrograms, indicator species and ordination analyzes. A total of 1333 species were found, of which 59 % were classified as exotic. The floristic profile of urban afforestation among States was characterized by a high richness of the Fabaceae family and by a high representativeness of Moquilea tomentosa, Mangifera indica and Ficus benjamina species. Native species had the lowest tree density values in the urban gradient examined, ranging from 2.2 +/- 0.36 tree/ha to 0.19 +/- 0.03 tree/ha. Based on the results from the NonMetric Multidimensional Scale (NMDS) ordination technique together with the cluster analysis, it was confirmed that the greatest floristic similarities were found among municipalities in the States located geographically closer together. It is concluded that floristic richness proportionally decreases with the expansion of metropolitan cities. These findings suggest that the urban afforestation in Amazonian cities, are not spatially or ecologically uniform. This information can help to make future decisions regarding the correct planning of species to be introduced into urban spaces in cities.