Conservation and enhancement of the green infrastructure as a nature-based solution for Rome’s sustainable development

Three quarters of the European population live in urban areas, which is expected to increase to over 80% by 2050. The well-being of urban citizens appears to be closely linked to the correlation between the growth of urban areas and to the availability of green spaces. The conservation and the enhancement of the Green Infrastructure (GI) can be considered a Nature-Based Solution (NBS) to improve the sustainability of urban development. From this perspective, it is important to identify priority areas close to existing GIs suitable to be preserved from further urban encroachment. Our study aims to draw up a methodology to identify priority areas and, accordingly, to expand the GIs. The main objectives are: (i) to identify the most sensitive areas of the GI to be preserved from urban encroachment; (ii) to locate arable lands in the vacant border territories between GIs and built-up areas, that, if converted into connected elements, would enhance the connectivity of the existing GIs whilst limiting land take; (iii) to define an index of priorities for increasing the GI territory by means of NBSs, taking into account the variability of GI coverage and level of legal protection for nature conservation across different neighborhoods in the city. This approach is applied to the GIs of the 15 administrative units of the municipality of Rome (Italy) as a case study. First, we focus on Urban Atlas classes to map the GIs in the municipality. We then use Morphological Spatial Pattern Analysis, implemented by a free software toolbox GUIDOS, to identify the key components of the GIs, such as hubs (core areas) and links (bridges). Then, a simulated new scenario is provided by including within the current GIs the agricultural lands outside protected areas, but within a buffer zone of 300 m from the land take. If the aforementioned agricultural lands, amounting to about 8000 ha, were converted into GI elements, they could lead to the improvement of connectivity and limit land take. Finally, in order to expand the area of the GIs, priority areas are selected within each administrative unit using an index based on the budget allocation process. The proposed methodology could be used: (i) by decision makers, looking for NBS in the design and planning of sustainable development of the city; and (ii) to enhance GI connectivity.