Prioritizing urban trees for carbon sequestration in South Korea: a multi-criteria approach

Abstract The recognition of the various functions of urban greenery and urban trees, including their greenhouse gas (GHG) absorption capacity, is expanding. However, studies on trees in urban areas are relatively limited compared with those in natural or non-urban areas, and the scope of research is limited to major tree species or specific stress-related factors. Here, we identified the main trees that can be planted in urban conditions in South Korea based on comprehensive literature review and expert opinions. We considered not only the inherent carbon storage abilities of trees, but also their ability to adapt and grow in urban conditions. First, based on the review, we selected 24 tree species portraying the highest preference and frequency of planting in urban areas, from a total of 166 forest tree species planted or recommended for planting in South Korea. The ecological suitability and economic feasibility of the selected tree species were analyzed based on expert opinions and the fuzzy multiple-criteria decision-making (FMCDM) model. This analysis led to the prioritization of the tree species, identifying those with the highest potential for urban planting. Some of the suitable tree species were Zelkova serrata, Ginkgo biloba, Chionanthus retusus, and Prunus yedoensis Matsum. To establish a systematic foundation for sustainable urban development and carbon neutrality, it is necessary to prioritize the development of carbon emission factors (CEFs) for tree species among the high-priority candidates currently lacking such data (e.g., Styphnolobium japonicum, Cornus kousa, Chamaecyparis obtusa, etc). Furthermore, the creation of an integrated planting model comprehensively considering various functions is essential. Our results can contribute to urban planning, design, and policymaking, especially with respect to the development of efficient carbon sinks.