Experimental analysis of PM_2.5 reduction characteristics between Korean red pine (Pinus densiflora) and sawtooth oak...

As global air pollution, particularly fine particulate matter (PM_2.5), has become a major environmental problem, various PM_2.5 mitigation technologies including green infrastructure have received significant attention. However, owing to spatial constraints on urban greening, there is a lack of management plans for urban forests to efficiently mitigate PM_2.5. In this study, we assessed the PM_2.5 reduction capabilities of Pinus densiflora (Korean red pine) and Quercus acutissima (sawtooth oak) by measuring the changes of PM_2.5 concentrations using an experimental chamber system. In addition, the PM_2.5 reduction efficiency in 90 min (PMRE₉₀) and the amount of PM_2.5 reduction per leaf area (PMR_LA) were compared based on arrangement structures and density levels. The results showed that the PM_2.5 reduction by plants was significantly greater than that of the control experiment without any plants, and an additional reduction effect of approximately 1.38 times was induced by a 1.5 m s^-1 air flow. The PMRE₉₀ of Korean red pine was the highest at medium density. In contrast, the PMRE₉₀ of sawtooth oak was the highest at high density. The PMR_LA of both species was highest at low densities. The different responses of the species to total reduction were well explained by total leaf area (TLA). The PMRE₉₀ of both species was positively correlated with TLA. The PMR_LA of sawtooth oak was approximately 2.3 times greater than that of Korean red pine. However, there were no significant differences in both PMRE₉₀ and PMR_LA between the arrangement structures. Our findings reveal the potential mechanisms of vegetation in reducing PM_2.5 according to arrangement structure and density. This highlights the importance of efficiently using urban green spaces with spatial constraints on PM_2.5 mitigation in the future.