Landscape trees sequester carbon during their growth processes, but they emit carbon through production in nurseries, which may offset carbon uptake. This study quantified the carbon footprint of landscape tree production. After determining the scope of life cycle for landscape tree production, the energy and material used to produce trees of a target size were analyzed by conducting a field survey of 35 nurseries. This energy consumption and input material were converted to an estimate of carbon emitted using data on carbon emission coefficients. The net carbon uptake was 4.6, 12.2, and 24.3 kg/tree for trees with a DBH of 7, 10, and 13 cm, respectively. Thus, even though carbon is emitted during the production process, landscape trees can act as a source of carbon uptake in cities that have high energy consumption levels. This study broke new ground for quantifying the carbon footprint of landscape tree production by overcoming limitations of the past studies that only considered carbon uptake due to absence of data on energy consumption and difficulty of field survey. These study results are expected to provide information on the carbon footprint of landscape trees and to be useful in determining optimal greenhouse gas emissions reduction goal through urban greenspaces.

Although street trees take up carbon by vegetation growth, they emit carbon directly or indirectly into the atmosphere due to the need for regular management, such as pruning and, irrigation, etc. This study estimates the annual carbon budget from the growth and management of urban street trees in South Korea and suggests management strategies to minimize the degree of management and annual carbon emissions. Annual carbon emissions from management practices such as pruning, irrigation, pesticide and fungicide application, and fertilization were estimated based on maintenance data, interviews with managers, and actual measurements. Annual carbon emissions from the management of urban street trees were calculated to be 2.4 kg/tree/year. From this total, pruning was the largest contributor at 91%. The average net carbon uptake for each street tree was 5.5 kg/tree/year. The street trees included in this study played an important role in carbon uptake, which was equivalent to 90–550% of the annual carbon emissions from street tree management. Based on these results, suggested management strategies include pruning, irrigation, pesticide and fungicide application, and fertilization. These study results will be useful for designing practical low-carbon landscapes with minimal management and carbon emissions.

Multifamily residential sites (MRS) are practical alternatives for securing a carbon uptake source in urban areas where hardscape is dominant, as trees must be planted in the lot area, according to the current landscape-related ordinances in Korea. Tree planting contributes to sustainability of residential sites through carbon reduction. This study quantified direct and indirect carbon reduction from tree planting in MRS in Korea and explored sustainable design guidelines to maximize the carbon offset service of MRS. The total annual direct and indirect carbon reduction through tree planting in all the MRS was estimated to be about 101.1 kt/year. This carbon reduction equaled 3.3% of the total annual carbon emissions from the heating and cooling energy consumption of multifamily buildings. This study considered both direct and indirect carbon reduction from trees in MRS which was insufficient in previous studies. The results of this study can be useful internationally by sharing the information of sustainable residential design in enhancing carbon offset service.

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 PM_2.5 in cities that lack sufficient greenspace. This study quantified C uptake and PM_2.5 deposition on street trees in the Republic of Korea and suggested sustainable design guidelines to enhance the effects of C and PM_2.5 reduction. The mean C uptake and the PM_2.5 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 PM_2.5 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 PM_2.5 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 PM_2.5 levels in greenspaces.