Understanding the Benefits from Green Areas in Rome: The Role of Evergreen and Deciduous Species in Carbon Dioxide Sequestration Capability

Urban areas are a major source of anthropogenic carbon dioxide (CO2) emissions because of road traffic and local heating with natural gas, oil or coal. Rome is among the largest European cities (129,000 ha) with a large volume of green areas (69.6% of the total Municipality area). The CO2 sequestration (CS) capability for the greenery extending for about 300 km2 inside the area delimited by the Great Ring Road (GRA) in Rome was calculated combining satellite data with CS data measured in the field. Data from Sentinel-2 were collected and the Normalized Difference Vegetation Index (NDVI) was computed on a pixel-base. Three plant classes homogeneous in terms of annual NDVI profile were identified: deciduous trees (DT), evergreen trees (ET) and meadows (M) covering an area of 14,142.027 ha within the GRA, of which M had the highest percentage (48%), followed by DT (27%) and ET (25%). CS ranged from 428,241,492.9 Tons CO2 year-1 (ET) to 263,072,460.6 Tons CO2 year-1 (M). The total CS of the greenery inside the GRA was 1049,490,355.4 Tons CO2 year-1 resulting in an annual economic value of $772,424,901.6/ha. The CO2 sequestration capability of the considered plant classes could be incorporated into the national greenhouse gas emission budget to calculate the contribution of CO2 sequestration to the economy of Rome.