Carbon reduction and planning strategies for urban parks in Seoul

Abstract

This study quantified carbon storage and uptake for urban parks in Seoul, the capital of the Republic of Korea. A total of 38 study parks were selected using a systematic random sampling method and all the trees in the parks were field-inventoried. Carbon storage and uptake by the park trees were estimated applying a quantitative model for urban open-grown trees of each species. Mean carbon storage per unit of park area, basal area, and crown cover by the trees was 38.5 ± 3.0 t/ha, 27.3 ± 0.8 kg/100 cm2, and 7.4 ± 0.4 kg/m2, respectively. Annual carbon uptake per unit area and cover by the trees averaged 3.5 ± 0.2 t/ha/yr, 2.5 ± 0.1 kg/100 cm2/yr, and 0.7 ± 0.0 kg/m2/yr, respectively. The major determinants of the levels of carbon storage and uptake were species, density, sizes, and layering structures of the planted trees. The trees across all urban parks in Seoul were estimated to store 222.3 kt of carbon and to annually sequester 20.2 kt of carbon. The trees in these parks played an important role in annually offsetting carbon emissions from gasoline consumption by approximately 2.3% of the total population of the city. The economic value of the annual carbon uptake, which was $7.1million/yr, equaled 15.1% of the annual maintenance budget of the parks in the city. However, the role of study parks as a source of carbon uptake was limited due to the distribution of large grass and impervious areas, the single-layered structures, and the dominance of small trees. Planning strategies were explored to enhance carbon reduction effects of the parks. They included the expansion of tree planting spaces through the minimization of unnecessary grass and paving areas, the active tree planting in the potential planting spaces, the multi-layered planting grouped with larger trees, and the planting of tree species having satisfactory growth rates. This study puts an emphasis on finding out the present carbon offset levels of urban parks on which information is limited and suggesting a future direction of park planning based on a detailed actual survey.