Carbon sequestration capability provided by different types of green areas in Rome

Carbon dioxide (CO2) has been recognized as a major driver of climate change accounting for over 80% of all greenhouse gas emissions in the European Union. In particular, urban green areas represent a sink of CO2 due to plants capacity to fix carbon via photosynthesis and store the carbon excess as biomass. However, the plant CO2 sequestration capability occurs at different rates depending on plant species, the relative growth rate and the photosynthetic capability. Rome is among the largest European cities, with a surface area of 1285 Km2, where the green areas represent 35.3% of the total surface. In such context, the main objective of this research was to quantify the plant CO2 sequestration capability (CS, Mg CO2 ha-1 y-1) by green areas of different size, location and vegetation types in Rome. In particular, four historical residences (Villa Pamphjli, 184 ha, Villa Ada Savoia, 160 ha, Villa Borghese, 74 ha, and Villa Torlonia, 14 ha), the Botanical Garden of Rome (12 ha) and the Campus of the Sapienza University of Rome (20.3 ha) were analyzed. The CS of the four historical residences were 780, 998, 664 and 756 Mg CO2 ha-1 y-1 respectively, the Botanical Garden 809 Mg CO2 ha-1 y-1, and the Campus 43.4 Mg CO2 ha-1 y-1. The results highlight the importance of green areas in cities in order to mitigate the atmospheric CO2 concentration increasing. Our data concerning CS capability by green areas might be incorporated in a geographic information system allowing the monitoring of CO2 concentration variations over time, implement strategies to maximize the urban vegetation ecological function and the management practices to fully realize the benefits of the services that green areas can provide.