After an extensive two-year long research effort, the results document the diversity of vascular plants that grow in the public spaces of Santiago, Chile. We analyze the taxonomic composition, life-forms and phytogeographic origin of the vascular flora of Santiago and, finally, we compare the results with those of urban areas in the Northern Hemisphere. We identified 508 species, 100 families, and 338 genera. The families that showed the greatest richness were Asteraceae and Poaceae. We found that at least 85.1% of the species are exotic. The life-forms are similarly represented, although chamaephytes and geophytes are poorly represented. We conclude that the composition of the urban flora of Santiago differs from that of most Northern Hemisphere cities, due to the increased presence of exotic species, which is likely a consequence of the historical and cultural patterns of ornamentation. Therefore it is likely that this urban area would be an adverse environment for the establishment and development of native species.

Urban forests are conformed by a variable representation of native and exotic species. Because these species differ in the morpho-functional traits that possess, they may have a differential participation in the provision of ecosystem services in cities. Here, we compare ecosystem services inferred from morpho-functional traits of native and exotic tree species present in Santiago, Chile. Five traits associated with ecosystem services valuation (V_i) were scored (1 versus 0), and compared between native and exotic tree species, weighting those ecosystem services according to multi-criteria decision analysis procedure (MCDA). We found that native and exotic species did not have significant differences in the ecosystem services provided to urban dwellers (F = 1.2; P > 0.05); but these results were obtained when ecosystem services were not weighted according to their demand in Santiago. When weights were pondered, native species provided more ecosystem services than did exotic trees (F = 7.1; P < 0.008). Complementarily, we also found that the ecosystem services ranked for native and exotic species did not correlate with their spatial distribution (occupancy, O_i). These results highlight the need to use criteria based on ecosystem services to tree planting in Santiago, prioritizing native species because, in comparison to exotic ones, they provide more ecosystem services demanded city dwellers.

The expansion of cities promotes the replacement of local biotas with exotic species causing a decrease in global diversity. As urbanization continues to expand, efforts directed towards the conservation within urban landscapes could support regional biodiversity conservation. The biogeographic region of central Chile displays a native flora of global importance because of its high endemism. Up to date, studies analysing the composition of the floras within the cities are scarce. The present study aims at characterizing the compositional and distributional patterns of the ornamental flora of five cities of central Chile (La Serena, Valparaíso, Santiago, Rancagua, and Talca). For this purpose, we sampled several streets and squares recording all woody species. The species were then characterized by their biogeographical origin and incidence. It was recorded 302 species of which approx. 86% were exotic and 14% were native, a consistent pattern found in the five cities studied; these results contrast with the European urban flora, where native species can usually overcome 50% of the plant species. Almost half of the exotic species had their origin in Asia (including Australasia, Temperate, and Tropical Asia), Europe, and North America. Consequently, the representation of the regional flora within the urban context is low for central Chile, with the native species registered, accounting for only 0.81% of the total species described for the country. Urban habitats could support regional biodiversity conservation, so a shift towards sustainable urban planning could promote local biological conservation.