Study on the microclimatic characteristics and human comfort of park plant communities in summer

Abstract

With the rapid worldwide urbanization, the environment quality has been worsening dramatically. It is a solid fact that the urban air temperature is gradually rising in all cities and some effective measures are needed to mitigate it. Planting of vegetation is one of the main strategies to regulate urban microclimate and mitigate the urban heat island (UHI). This paper aims to investigate the effect of tree community, mainly through shading, on the improvement of microclimatic conditions in urban areas, specifically, in the case of Beijing Olympic Forestry Park in Beijing, China. The microclimate characteristics of different communities were analyzed, and the discomfort index (DI) was introduced to evaluate the effects of different tree communities on human body′s comfortable degree. The results showed that there existed significant differences in the air temperature, relative humidity and light intensity between tree communities and the control open space site (CK). Compared with CK, the tree communities can decrease temperature by 1.6∼2.5°C increase the humidity with 2.9%∼5.2%. The differences of DI among tree communities and CK are not significant, however, compared to the CK, all species communities are able to reduce the diurnal mean DI in some degree. Correlation analysis between microclimate factors and the indices of the tree communities canopy structural characteristics show that canopy characteristics play important regulatory role in microclimate and DI degree. The intention of this work is to provide more basic and solid information to aid human′s understanding the role of plant on mitigation of the urban heat island, and specifically, to aid efforts to improve the environment of Beijing through better planning and the appropriate choice of plant species used for landscape design, and for references of other cities that have similar climatic characteristics as well.