Estimation of biomass allometric equations and biomass expansion factors for three tree species of urban trees in South Korea

The National Institute of Forest Science (NIFoS) developed the Korean i-Tree by the collaboration research with US Forest Service from 2018 to 2023. The i-Tree is an effective method for non-destructively and effectively calculating the carbon storage of trees at urban areas in South Korea, which is full of obstacles. However, there might be differences in the amount of carbon storage depending on the growing conditions between urban and rural regions in South Korea. Therefore, this study was conducted to suggest conversion factors urban to rural regions adaptable to the environment and circumstances in Korea. This study analyzed 12 Korean research papers and differences in growth rates between forest trees, landscaping trees, and street trees for 14 forest species and 11 urban trees. There was a difference of average biomass ratio of 0.52 in Korean red pine, 0.22 in Korean pine, 0.52 in Ring-cup oak and that of 0.39 in Red-wood evergreen oak between urban and rural areas. Those values were lower than 0.80, which is the biomass conversion factor of the rural and urban of the i-Tree. Also, there was a difference in the relative values between landscaping trees and street trees of the same species in urban regions. Therefore, it would be suggested to apply a value of 0.43 rather than 0.80 when calculating the amount of carbon storage and sequestration for trees by applying the i-Tree in Korea.