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• Longer flowering and fruiting in urban trees of brazilwood in comparison to forest remnant. • Larger flowers with less pollen in urban trees of Paubrasilia echinata. • Impairment in the pollination process of Paubrasilia echinata in urban ecosystem. • Reduced reproductive success of brazilwood in urban compared to natural ecosystem. Human activities have drastically altered natural ecosystems, mostly by converting forests into agricultural and urban areas. Brazilwood (Paubrasilia echinata) is an endangered tree endemic to the Brazilian Atlantic forest originally occurring along the whole coast. The species is largely planted in urban areas due to its ornamental potential. In this paper, we compared the phenology, floral traits and the reproductive success of P. echinata between urban and natural ecosystems. We have hypothesized that individuals in urban ecosystem will have: i) reproductive phenophases lasting longer than in natural, ii) lower number of pollen grains and ovules per flower, iii) lower richness and frequency of flower visitors, and iv) lower natural fruit and seed set. The study was carried out in urban green spaces of the city of Recife and in an Atlantic forest remnant, both in Pernambuco State, northeastern Brazil. The species flowered and fruited practically all year round in the urban ecosystem, contrasting with the annual pattern of flowering and fruiting observed in the natural area. We documented that brazilwood trees in urban areas had smaller inflorescences, fewer flowers/inflorescences, larger flowers, less pollen/flower, lower richness of floral visitors and lower fruit and seed set when compared to natural ecosystem. Also, when considering the most frequent effective pollinator, the invasive bee Apis mellifera predominated in urban, whereas the autochthonous pollinator Centris aenea prevailed in natural. Moreover, C. aenea acted as occasional pollinator in urban area because the flowers of P. echinata are larger in this ecosystem. Independent of the underlying mechanism, the brazilwood had an impoverished richness of native pollinators and a significant reduction in the reproductive success in urban ecosystem, indicating an impairment in the pollination process. The viability of planting trees in tropical urban areas as an ex-situ conservation alternative for species obligatory dependent on cross-pollination, such as P. echinata , may be compromised. [ABSTRACT FROM AUTHOR]

• Exotic trees predominate in tropical urban spaces. • 100 % of self-incompatible exotic trees set fruit in tropical urban ecosystem. • Exotic trees pose risk to native species and threaten urban and natural ecosystems. • Native plants should be the first choice in tropical urban ecosystems. Urban ecosystems provide green landscapes that are important to global biodiversity conservation. In tropical urban ecosystems, exotic plants are widely used in landscaping and this can have several negative effects on the native plant and pollinator communities. Here, we aimed to investigate the origin (native or exotic to Brazil, and native or exotic to the phytogeographic dominium where the urban space is inserted), sexual and reproductive systems and fruiting of tree species occurring in 17 urban green spaces in the city of Recife, Pernambuco, located in the northeastern Brazilian Atlantic forest. A total of 114 tree species were registered in the urban green spaces, 78 out of them were observed for fruiting. Overall, 49.1 % of the species are native to Brazil and 50.9 % are exotic, while 86 % do not occur naturally in the northeastern Brazilian Atlantic forest. In terms of abundance of individuals, these values were 37 % native, 63 % exotic and 80.5 % not occurring in the northeastern Brazilian Atlantic forest. Most of the species, native or exotic, are hermaphrodite and self-incompatible (i.e. obligatory cross-pollinated). From the 78 species observed for fruiting, 77 set fruits, 43.7 % had sub-annual pattern; all exotic species (43 spp.) set fruits, even the 13 exotic species that are self-incompatible. Our results reveal that factors such as the high use of exotic species that successfully set fruits in tropical urban green spaces may indicate risks for plant-animal interactions (e.g. pollination; dispersion), threaten the reproductive success of native plant species, increase the risk of biological invasion, and consequently impair the maintenance of biodiversity. We suggest that decision makers pay attention and consider the impacts of using exotic plant species in the dynamic of tropical urban ecosystems. [ABSTRACT FROM AUTHOR]