by A Speak, FJ Escobedo, A Russo, S Zerbe
Journal of Cleaner Production 256: 1204202020
Cities are key sites for carbon emission mitigation programs due to transportation and energy consumption. Urban forests provide numerous ecosystem services, as well as reducing energy consumption through shading. The carbon stored in the trees suggests that urban forests could help offset a city’s carbon emissions from other sources. The aim of this study was to complete a realistic life-cycle assessment of the carbon sequestration potential of Meran, Italy. The authors utilized multiple techniques in their assessment: the i-Tree application, Light Detection and Ranging (LiDAR), field methods, and Allometric equations. The carbon storage estimates using Allometric equations and two i-Tree methods were all within 4% of each other, 8923-9213 Mg, for an average of 13.5 t/ha. These storage estimates equate to the sequestration of 0.17-0.61% of annual traffic emissions, or 0.05%-0.17% of total annual emissions. There was variation across the land types, with public lands (i.e. street, park, cemetery) having the highest sequestration. In contrast, private lands such as houses and apartments (where over half the street trees were located) had relatively average carbon storage and sequestration values. The unoccupied areas, city center, hospital and commercial grounds, and vineyards had the lowest totals. The effect of different wood waste management practices on carbon sequestration was also explored. The least efficient option was for the wood waste to go to the landfill and burning the wood waste, with energy recovery for electricity, was the most efficient method with the lowest carbon emissions/input ratio. This suggests that cities should avoid sending wood waste to landfills and instead promote a circular economy approach. Meran’s carbon storage was lower than the average for urban areas in the United States; potentially reflecting a cultural preference for smaller trees and/or the lack of large tree-rich suburbs. Overall, the low storage and sequestration calculations suggest that tree planting is not an efficient method of achieving carbon neutrality in a city; although the urban forest still provides other important benefits.