A “Street Tree” Master Plan for the Strategic Management of Linear Reforestation and Urban Landscape Enhancement in Rome, Italy

Trees in urban environments play a crucial ecological role, helping to mitigate air pollution, reduce urban heat islands, improve stormwater drainage, and provide essential ecosystem services such as biodiversity conservation. Street trees, in particular, form an interconnected network within the urban fabric, offering the potential to link various green spaces across the city. Several cities have implemented dedicated Street Tree Master Plans (STMPs) to manage street trees effectively. A STMP thus serves as both a vital tool for the management and conservation of urban tree heritage and an opportunity to enhance public spaces and the quality of life for citizens. This case study of Rome (Italy) presents a particularly complex challenge, partly due to the city’s rich historical heritage, where street trees contribute to the identity of places and the urban environment in the context of climate change. The tree heritage of Rome requires ongoing maintenance, the improvement of growing conditions, the replacement of hazardous or aging trees along street rows, and the addition of new trees to enhance and diversify the urban tree population. Starting from a new census of street trees and a spatial analysis using GIS methodologies, this study examines the approach taken by Rome’s STMP. It focuses on the different strategies proposed for various types of streets, classified on the specific role that trees play in each context. Specifically, the plan offers a strategic vision for the city’s future, rooted in its urban form and supported by a methodological framework for planning interventions based on the current condition of tree cover. Drawing on insights from the STMP, the findings emphasize that any comprehensive renewal of street trees in large cities with historically significant and aesthetically rich landscapes must be guided by a strategic vision. In the discussion, a comparative analysis was conducted on different STMPs in various cities around the world, and we questioned how significantly historical and spatial considerations, which characterized the formation of Rome’s STMP, should be part of all STMPs.