Fine particulate matter (PM2.5) reduction capacities and their relation to morphological and physiological traits in 13 landscaping tree species

Kunhyo Kim, Heejin Jung and Jeonghyun Hong, Department of Agriculture, Forestry and Bioresources, Seoul National University, Seoul, Korea, Republic of (South), Jihyeon Jeon, Forest resources, Kanwon National University, Chunchun, Korea, Republic of (South), Tae Kyung Kim and Hyun Seok Kim, Department of Forest Sciences, Seoul National University, Seoul, Korea, Republic of (South), Gi-Seong Jeon, Korea Expressway Corporation Research Institute

Background/Question/Methods
With the increasing use of fossil fuels, fine particulate matter (PM2.5) is emerging as a serious environmental problem worldwide. In particular, the damage caused by PM2.5 in urban areas, where industrial complexes and human activities are concentrated, is extremely problematic, posing a threat to human health. Thus, the importance of landscaping trees is increasing because of their ability to reduce PM2.5; however, there remains a lack of research on the selection of species and tree management for PM2.5 reductions. In this study, we quantified and compared the PM2.5 reduction capacities of 13 major landscaping tree species and analyzed the relationship between the morphological and physiological characteristics of each species and PM2.5 reduction.
Results/Conclusions
Results showed that the amount of PM2.5 reduction differed among species; reduction per leaf area was the highest in Ginkgo biloba (28,165 ± 5,353 # cm-2 min-1) and the lowest in Pinus strobus (1,602 ± 186 # cm-2 min-1). Moreover, PM reduction by the broadleaf species (18,802 ± 1,638 # cm-2 min-1) was approximately 8.6-fold that by the needleleaf species (2,194 ± 307 # cm-2 min-1). Correlation analysis revealed that differences in PM2.5 reduction were described by specific leaf area between species (P = 0.004), and explained by the length of margin per leaf area among individual trees (P < 0.05). Additionally, reduction in PM2.5 correlated with photosynthetic properties such as maximum assimilation and carboxylation rates, indicating that PM2.5 is reduced not only by physical but also by physiological processes (P < 0.001). These findings emphasize that for effective reduction in PM2.5 through landscaping trees, comprehensive consideration of the morphological and physiological characteristics of the species is essential in species selection and that continuous management is also necessary to maintain the active physiological conditions of the trees.