Intended wilderness as a Nature-based Solution: Status, identification and management of urban spontaneous vegetation in cities

Abstract

Nature-based Solutions (NbS) have been an increasingly recognized framework that uses naturally occurring processes to maximise the provisioning of ecosystem services and improve the life quality of city dwellers. One of the more widely applied NbS is an intentional abandonment of green space cultivation and promoting wilderness. In this study, we developed urban spontaneous vegetation (USV) identification algorithm based on NDVI from Sentinel-2 data in Warsaw’s green spaces, Poland. We verified the study in an on-site survey where we collected 2863 field reference plots for USV and cultivated vegetation identification. We achieved 74 % accuracy for USV and 70 % for cultivated vegetation identification. The study assessed the spatial resources and extent of USV in the scale of the city and within various types of urban greenery. We identified the vegetation development persistence over 3 years and assessed the spontaneity levels of urban greenery. Classification of Warsaw’s vegetation revealed that 54 % of Warsaw’s greenery is cultivated while the remaining part is characterized by various levels of spontaneity. Only in 34.7 % of USV, we found no interruption of vegetation development due to cultivation for at least 3 years. USV was common in both cultivated parks where it accounted for 46.6 % of vegetation, as well as in the vacant lots, where it occurred in 55.3 % of the area. The proposed USV detection methodology can be an efficient tool for restoration effectiveness assessment and can support cultivation abandonment as NbS - an intended action promoting wilderness.