Assessing air pollutant removal and carbon sequestration across urban forest stands and individual species in a medium-sized southern Italian city.

Urban areas are characterized by elevated levels of air pollution and carbon emissions resulting from human activities. Addressing these challenges simultaneously is essential for achieving resilient and healthy cities. Given the potential of urban forests to mitigate both air pollution and carbon emissions, this study focused on quantifying these ecosystem services in Monte Sant'Antonio's urban forest, located in Campobasso, Italy. The urban forest's capacity to remove carbon and atmospheric pollutants (O, SO, NO, CO, and PM) was first assessed using i-Tree Eco v.6 software. The results from i-Tree Eco were then compared with estimates we developed using Italian biomass calculation equations from the 2015 National Inventory of Forests and Carbon Sinks. To support this comparison, linear regression models were developed to characterize the relationships between total tree biomass (independent variable) and pollutant removal and carbon sequestration (dependent variables) by individual tree species. The analysis followed a stepwise approach. Subsequently, we assessed temporal variations in air pollutants removal capacity and gross carbon sequestration for the two tree species present in all four stands analyzed: Fraxinus ornus L. and Pinus nigra J.F. Arnold. Based on the estimates derived from applying the models using total tree biomass calculated with Italian equations, the urban forest of Monte Sant'Antonio can remove approximately 1 ton of pollutants per year (CO, O, NO, SO, PM) and approximately 158 tons of gross carbon sequestration per year.