Variation in Urban Forest Regulation of Air Particulate Matter Concentration

Abstract

Urban forest was vital to adjusting Air Particulate Matter Concentration (APMC). The purpose of this study was designed to provide a more detailed analysis of the urban forest long-time scales effect on APMC. The paper assessed effect of forests (urban greening) on APMC in an urban environment, where an urban green center (nearly 2 km2) and a nearby (5 km away) bare-ground site (at a road intersection) in Yuhua District of Changsha, China, were chosen to delve into daily, seasonal, and annual variation of APMC in an urban forest and a non-forested site respectively. It was found that: (1) on a daily basis, APMC in both the urban forest and the non-forested site was high in the morning and evening, but low at noon, demonstrating a “two-peak-one-trough” or V-shaped pattern. Additionally, APMC in the morning was higher than evening. (2) in terms of season, APMC was high in spring and winter, but low in summer and fall. (3) the annual change of the APMC showed a “bimodal” annual trend in urban forest and non-forested site, with a peak concentration in the urban forest coming later than the non-forested site. (4) temperature and average wind speed composed main factors affecting APMC in Changsha’s ecotope. The paper characterized the change pattern in APMC in urban environment (forested and non-forested), suggested appropriate recreational periods in the urban forest, and gave insight in planning and construction of urban greening projects.