Urban Forest Locations and Patch Characteristics Regulate PM[sub.2.5] Mitigation Capacity

Atmospheric pollution caused by fine particulate matter (PM[sub.2.5] ) seriously damages human health. Urban forests have the ecological function of purifying the atmosphere, which can effectively reduce the ambient PM[sub.2.5] concentration. This paper analyzed the ability of different forest types to mitigate PM[sub.2.5] pollution and explored the effects of forest quality and morphological parameters on PM[sub.2.5] concentration on the forest patch level. The results concluded that the PM[sub.2.5] concentration of the Landscape and Relaxation Forest (LF) was significantly lower than that of the Roadside Forest (RF) and Affiliated Forest (AF) due to the environmental quality of their location. The effective distance of LF on PM[sub.2.5] reduction was 80 m, which was significantly higher than RF and AF. The Normalized Difference Vegetation Index (NDVI), which indicated forest growth status, was the most effective parameter for improving the urban forest PM[sub.2.5] mitigation ability. The concentration of PM[sub.2.5] decreased linearly with the increase in NDVI. The area and perimeter of the forest patches had a significant nonlinear negative correlation with PM[sub.2.5] concentration. In addition, the more irregular the shape of the forest patch, the lower the PM[sub.2.5] concentration of the forest. Moreover, the simpler shape of RF and AF helped to alleviate PM[sub.2.5] pollution. The round shape of AF more efficiently reduced PM[sub.2.5] concentration. Our study demonstrated that the surrounding environment, forest growth status, and patch forms determined the PM[sub.2.5] reduction capacity of an urban forest. The corresponding management and adjustment methods should be implemented in future urban forest management.