## 3 Results
### LCA Analysis  
The assessed environmental benefits provided by the current and the potential tree cover are configured as an annual sequestration/absorption of different potentially harmful substances in the atmosphere and as avoided water runoff that could cause hydrological damages. These benefits can be translated into LCA-avoided impacts, expressing the annual avoided repercussion in different, specific environmental sectors, thanks to the presence of trees delivering their functions. The LCA analysis of the ecological functions provided by the present and the potential assessed tree cover is reported in Table 6. The different air pollutant substances sequestered by trees and the avoided runoff in the two scenarios affect six ReCiPe midpoint (H) impact categories: global warming; ozone formation, human health; fine particulate matter formation, ozone formation, terrestrial ecosystems; terrestrial acidification; water consumption. The results confirm once again the linear correlation between environmental benefits and the presence of trees proposed by the i-Tree Canopy tool.  
Planting new trees in urban environments presents both economic and environmental costs due to the cultivation of tree seedlings in specific nurseries, involving energy, chemicals, and machinery, among other input flows. A careful accounting of the mentioned environmental burdens against the analysis of benefits coming from the presence of trees could facilitate afforestation projects and urban green management plans. Table 7 shows the  
\begin{table}
\begin{tabular}{l l l l} \hline \hline
**Impact Category** & **Unit** & **Present** & **Potential** \\ \hline Global warming & kg CO\({}_{2\text{ eq}}\) & \(1.12\times 10^{8}\) & \(1.70\times 10^{8}\) \\ Ozone formation, human & kg NO\({}_{\text{x eq}}\) & \(8.16\times 10^{4}\) & \(1.23\times 10^{5}\) \\ health & & & \\ Fine particulate matter & kg PM\({}_{2.5\text{ eq}}\) & \(4.85\times 10^{4}\) & \(7.33\times 10^{4}\) \\ formation & & & \\ Ozone formation, terrestrial & kg NO\({}_{\text{x eq}}\) & \(8.16\times 10^{4}\) & \(1.23\times 10^{5}\) \\ ecosystems & & & \\ Terrestrial acidification & kg SO\({}_{2\text{ eq}}\) & \(9.96\times 10^{4}\) & \(1.50\times 10^{5}\) \\ Water consumption & m\({}^{3}\) & \(2.22\times 10^{5}\) & \(3.35\times 10^{5}\) \\ \hline \hline \end{tabular}
\end{table}
Table 6: Characterized ReCiPe midpoint impacts avoided by the present and the possible tree coverage in the Metropolitan City of Naples.  
\begin{table}
\begin{tabular}{l l c c} \hline \hline \multirow{2}{*}{**Benefit**} & \multirow{2}{*}{**Description**} & \multicolumn{2}{c}{**Value (USD)**} \\ \cline{3-4}  & & **Present** & **Potential** \\ \hline Carbon sequestration & Sequestered annually in trees & 21,126,481 & 31,900,144 \\ \hline \multirow{4}{*}{Air pollution removal} & CO & 2242 & 3385 \\  & NO\({}_{2}\) & 5143 & 7766 \\  & O\({}_{3}\) & 1,486,373 & 2,244,364 \\  & SO\({}_{2}\) & 1654 & 2497 \\  & PM10 & 479,582 & 724,149 \\  & PM2.5 & 739,064 & 1,115,957 \\ \hline Hydrological & AVRO & 577,302 & 871,703 \\ \hline
**Total** & & 24,417,841 & 36,869,965 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Hydrological benefits from tree coverage in Megalitres (MI).  
ReCiPe midpoint impacts of the production and plantation of 2.34 million tree seedlings, according to the Ecoinvent database used in this study. The comparison between the numbers in Tables 6 and 7 suggests that the impacts of tree production and planting would be entirely compensated by the functions provided by these new trees in a little more than half a year (\(\approx\)200 days).