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This study compared carbon (C) and nitrogen (N) distribution at a stand level in an exotic Japanese cedar (Cryptomeria japonica D. Don) plantation and a natural Serrata oak (Quercus serrata Murray) stand growing under similar site conditions in South Korea. The aboveground biomass (stems, branches, and leaves) of 20 trees (10 of each species), the forest floor, and the mineral soils to a depth of 30 cm were sampled to determine C and N concentrations. Except in branches, C concentrations were significantly higher (p &lt, 0.05) in the Japanese cedar plantation than in the Serrata oak stand, whereas N concentrations, except in the stem bark, were significantly lower in the Japanese cedar plantation. Reforestation with an exotic coniferous species significantly increased the C stocks in the aboveground biomass and the N stocks in the forest floor and mineral soils compared with a natural oak stand. The N stocks in the aboveground biomass were dependent on either the N concentrations or the C stocks in the tree components, whereas soil C and N stocks were negatively related to soil fertility parameters such as C/N ratio. Although it is uncertain which factors are responsible for the difference in aboveground C and soil N stocks following the establishment of Japanese cedar plantations on former natural Serrata oak stands, tree replacement may have an impact on C and N allocation within different forest compartments.

Broad-leaved evergreen trees create urban forests for mitigation of climate warming and adsorption of particulate matter (PM). This study was performed to identify the species suitable for urban greening by examining the adsorption capacity of the evergreen species in urban areas in Korea, the adsorption points and the elemental composition of PM in the adsorbed tree. Leaf sampling was carried out four times (period of seven months from October 2017 to May 2018) and used after drying (period 28 to 37 days). Particulate matter (PM) was classified and measured according to size PM2.5 (0.2–2.5 μm), PM10 (2.5–10 μm), PM100 (10–100 μm). The total amount of PM adsorbed on the leaf surface was highest in Pinus densiflora (24.6 μg∙cm−2), followed by Quercus salicina (47.4 μg∙cm−2). The composition of PM adsorbed by P. densiflora is 4.0% PM2.5, 39.5% PM10 and 56.5% PM100, while those adsorbed by Q. salicina are evergreen at 25.7% PM2.5, 27.4% PM10 and 46.9% PM100. When the amount of PM adsorbed on the leaf was calculated by LAI, the species that adsorbed PM the most was P. densiflora, followed by Q. salicina, followed by Q. salicina in the wax layer, then P. densiflora. As a result of this study, the amount of PM adsorbed per unit area of leaves, and the amount of PM calculated by LAI, showed a simpler pattern. The hardwoods had a high adsorption rate of PM2.5. The adsorption ratio of ultra-fine PM2.5 by evergreen broad-leaved trees was greater than that of coniferous trees. Therefore, broad-leaved evergreens such as Q. salicina are considered very suitable as species for adsorbing PM in the city. PM2.5 has been shown to be adsorbed through the pores and leaves of trees, indicating that the plant plays an important role in alleviating PM in the atmosphere. As a result of analyzing the elemental components of PM accumulated on leaf leaves by scanning electron microscopy (SEM)/ energy dispersive x-ray spectroscopy (EDXS) analysis, it was composed of O, C, Si, and N, and was found to be mainly generated by human activities around the road. The results of this study provide basic data regarding the selection of evergreen species that can effectively remove aerial PM. It also highlights the importance of evergreen plants for managing PM pollution during the winter and provides insights into planning additional green infrastructure to improve urban air quality.