Carbon and PM2.5 Reduction and Design Guidelines for Street Trees in Korea

Abstract

An increasing concentration of air pollutants, which negatively affect human health and living environment, present a serious environmental concern around the world. Street trees can help reduce carbon (C) and PM2.5 in cities that lack sufficient greenspace. This study quantified C uptake and PM2.5 deposition on street trees in the Republic of Korea and suggested sustainable design guidelines to enhance the effects of C and PM2.5 reduction. The mean C uptake and the PM2.5 deposition on street trees per unit area were 0.6 ± 0.1 t/ha/y and 2.0 ± 0.3 kg/ha/y, respectively. The major determining factors of the levels of C uptake and PM2.5 deposition on street trees were the species, density, size, and layering structure of the planted trees. Street trees in the Republic of Korea annually offset C and PM2.5 emissions from vehicles by 1.4% and 180%, respectively. Based on these results, design guidelines are suggested that can contribute to sharing the value and the importance of planting street trees for the reduction of C and PM2.5 levels in greenspaces.

Improvement of the Planting Method to Increase the Carbon Reduction Capacity of Urban Street Trees

“…Meanwhile, the street tree cover of some cities in Korea was approximately 12.5% (Jo et al, 2020b), indicating that the street tree cover in this study is about 47.5% of the cities in previous studies.…”

“…The study cities were selected among those without research on street trees and carbon, considering the national and regional distribution of the city in previous studies (Jo, 1999;Jo et al, 2003;Park and Kang, 2010;Park, 2015b;Jo et al, 2018Jo et al, , 2020bJo, 2020). Provinces without domestic research on carbon were Chungbuk, Jeonbuk, Gyeongnam, and Jeju.…”

“…We examined tree species and their horizontal and vertical structures including diameter at breast height (DBH), diameter at root collar (DRC), tree height, crown width, population, and layer, as well as the street environment such as the number of lanes, sidewalk width, and planter width on each site. The site was set vertically up to 80 m with 40 m each from the sample point, and horizontally up to the building boundary of the sidewalk including the road (Jo et al, 2018;2020b) (Fig. 2).…”

“…2, 2021 cal measures such as minimizing consumption of fossil fuels and developing and increasing supply of alternative energy resources, as well as to maintain and expand carbon sinks by establishing various types of greenspace and managing them efficiently. Urban trees planted in the streets, gardens, and parks absorb and store atmospheric carbon in their growth process and contribute to carbon accumulation of soil (Jo et al, 2020b). In particular, street trees perform a key role in reducing the concentrations of carbon emissions from vehicles, being closest to their direct and indirect sources.…”

“…Studies in Korea and overseas on carbon uptake in greenspace of streets (Jo and Cho, 1998;Jo, 1999;Jo et al, 2003;Park and Kang, 2010;Kim et al, 2011;Kim, 2013;Russo et al, 2015;Park, 2015a;Park, 2015b;Tang et al, 2016;Jo et al, 2018;Zhao et al, 2018) have been conducted since the late 1990s. Recently, Jo (2020) and Jo et al (2020b) have quantified the carbon uptake of street trees in some cities of Korea and provided planting guidelines to maximize it. However, studies in Korea thus far merely provided results limited mostly to big cities or parts of Gangwon-do, or applied methods using satellite image instead of field survey, and thus research data on street trees by city and region is still limited.…”