Developing and classifying urban biomes as a basis for nature-based solutions

Abstract

Urbanization is a major driver of environmental change, which calls for multifunctional and comprehensive actions such as Nature-based Solutions (NbS). They are “inspired and supported by nature… and must benefit biodiversity and support the delivery of a range of ecosystem services”. But what nature should one aim for? We tested the hypothesis that local vegetation may not always be the best source of inspiration, as environmental changes impact both extant conditions and species suitability for restored ecosystems. We analyzed the megacity of São Paulo, where laws promote the use of species from the local Atlantic Forest biome. We trained a Linear Discriminant Analysis to classify the Brazilian biomes and predicted the biomes' correspondence considering city's vegetation cover and climate. With 80% accuracy, the model predicted correspondence with the Atlantic Forest in 57% of the city, while 43% is better represented by the Cerrado, a dense Tropical Savanna biome. Cerrado species are naturally adapted to higher insolation, temperature and more seasonal precipitation, and they can parallel the ecosystem services of the Atlantic Forest. To help guide NbS implementation, we consider four “urban biomes”: Atlantic Forest, Seasonally Flooded Atlantic Forest, Cerrado, and the Seasonally Flooded Cerrado, whose dynamics seem to depend mainly on changes in the proportion of dense vegetation cover. We then discuss possible examples of NbS in the city. ResultsAccording to the PCA (Tables S3-S6), the main difference between the classification of the green spaces classified is the higher proportion of forest cover in those classified as Mata Atlantica, with almost any influence from other vegetation cover types (Fig. 5E). This pattern is still consistent when vegetation cover is evaluated outside the largest green spaces where the presence of even small forest patches across the urban fabric results in the Mata Atlântica category DiscussionThe urban ecosystem restoration could benefit from such natural and dynamic processes in which the Cerrado could act as a transient urban biome in the way of restoring the urban forests through soil horizon development and species succession followed by the densification of the vegetation whenever this planting scheme is possible. ConclusionsThese transitions among urban biomes may occur as local conditions change with the implementation of NbS, and the results point to the effectiveness of increasing the vegetation density wherever possible.