Street tree abundance, composition, and (mal)distribution in Lagos Metropolis, Nigeria

Abstract

Street trees provide critical ecosystem services and economic benefits that support urban livelihoods. To effectively manage street trees over the long term and maximise their benefits, information on their abundance, composition, and distribution is needed. Unfortunately, a lack of data is prevalent in most cities, particularly those in the developing countries. To address this, species, basal diameter, height, and location of 4,017 street trees were collected from all 16 local government areas (LGAs) of Lagos metropolis (two wards per LGA) to assess their abundance, composition, and distribution. Forty-six species, 37 genera, and 25 families were identified, with Polyalthia longifolia (27.3 %) being the most prevalent species. Most (87 %) of the trees were non-native, and the highest percentage (78.1 %) had basal diameters between 20 and 40 cm. The LGAs which harbour the wealthiest neighbourhoods in Lagos (Ikeja and Eti-osa), have higher species abundance and richness. The Gini coefficient is 0.81, indicating unequal distribution of street trees within different LGAs that made up the metropolis. These results highlight the need to plant a diverse set of species, particularly native species that can provide multiple benefits. The information obtained in this study could provide insights into which species should be planted and where they are most needed to ensure distributional equity. Future studies could seek to understand the key limitations of street tree establishment and management in Lagos metropolis.