Changes in the Spatial Pattern and Ecological Functionalities of Green Spaces in Lubumbashi (the Democratic Republic of Congo) in Relation With the Degree of Urbanization

An accurate description of spatial urban growth is a prerequisite step in order to implement appropriated policies to improve the ecosystem service performance of green spaces in a city. Such information is, however, absent in Lubumbashi, the second metropolis of the Democratic Republic of Congo, despite its high demographic growth rate and an unplanned spatial urban growth. This study was designed to characterize the spatial pattern of green spaces and the extent of changes driven by the urbanization along the urban-rural gradient using a combination of landscape metrics and floristic plots. Our results revealed that the number of patches was directly proportional to the degree of urbanization of the city, whereas the area of the green spaces and the index of the largest patch showed an inverse relationship with the urbanization degree. Urban green spaces were dominated by attached and roadside spaces that are more equipped and present a higher occurrence of cultivated plants. By contrast, peri-urban green spaces were characterized by buffer zones, fields, abandoned areas, and informal spaces, with an elevated proportion of invasive species and natural vegetation. Moreover, it was found that the number of exotic species increased with the degree of urbanization, reaching values considered a threat to the indigenous flora. The current results underline the need for urgent measures oriented both toward increasing the spatial connectivity between green spaces (e.g., by creating new green spaces planted with indigenous species) while reducing the spread of invasive species in the city.