A check list of plant species in the urban forestry of Fortaleza, Brazil: where are the native species in the country of megadiversity?

Although Brazil is recognized as a country of megadiversity many Brazilian cities have an overwhelming number of exotic street trees in their urban environments. Here we investigate this situation in the city of Fortaleza, Brazil's fifth largest city. Through an extensive qualitative survey, complemented by published quantitative surveys, we developed the most complete inventory done to date in Fortaleza. We registered the largest possible number of plant species which we could record in the public treescape of the city. We recorded 219 tree species, of which 158 were exotic to Fortaleza's ecosystems. Of the 61 native species, some were represented only by relictual individuals spared during urban growth and only 39 native species were cultivated plants. Most of these 39 cultivated natives are represented by a small number of individuals in the city, while most of common trees are exotic species. We show that many native plants that are potentially suitable for ornamental use in urban settings are being ignored and argue that exotics are overvalued, including some plants that are invasive. We also discuss the consequences of the predominance of alien species for the public perception of native biodiversity. We advocate that increasing the number of native plants in cities has many advantages from an ecological perspective.