Potential Evaluation of Carbon Storage by Urban Trees (Case Study: Hamadan)

Urban is a unique and inconsistently defined land cover including green and grey infrastructures. Tree covers that can store large stocks of carbon. There are several ways to estimate a tree's CO2 sequestration. In this study, Google Earth images were used for mapping tree covers in the Hamadan urban scale with an area of 7422 hectares. First, a 50-meter buffer was applied on two sides of the main streets. Then, it was classified into three groups called high, medium, and low density based on the percentage of greenery. In each group, the information of 265 trees (the total of 800 trees) were recorded randomly such as allometric data and canopy diameter of trees. An Object-Oriented approach was applied to extract the area and canopies of individual urban trees. The total number of trees and their location were estimated by dividing the total of trees canopy by the average of the individual urban trees canopy. Allometric equations were used to estimate the dry biomass of tree species. Based on the results, the main species in the study area include maple, black locust, sycamore, manna ash, cypress, fir tree, and elm. The average amount of organic carbon stored in individual and street trees with asphalt and cobblestone pavement is estimated to be about 88.29 kg, which differs significantly from those with the surface covered by soil and grass (an average value of 148.79 kg). In total, the amount of organic carbon stored by Hamadan urban trees is estimated to be 1.6 tons per hectare.