Urban green infrastructure (UGI) refers to the natural and semi-natural open spaces with ecosystem functions in and around the cities. Improving urban green infrastructure is considered as an important technical means for the effective control of atmospheric PM_2.5 (particles aerodynamic diameter of lower than or equal to 2.5 μm) pollution. High-speed urbanisation and industrialisation, however, have brought a large number of pollution sources, causing PM_2.5 pollution to be increasingly serious, and they have encroached on a large range of urban green spaces, resulting in drastic changes in landscape patterns and functions (e.g., dust retention performance) of UGI. Therefore, it is very important to further understand the relationship between UGI landscape pattern change and PM2.5 pollution in the context of urbanisation. 

In view of this, Associate Prof. Li Chunlin and other researchers from the Landscape Ecology Group of the Institute of Applied Ecology (IAE), Chinese Academy of Sciences, took the urban agglomeration in central Liaoning, a region of rapid urbanisation, as an example, and analysed the relationships between UGI landscape patterns and PM2.5 concentrations at urban agglomeration and neighbourhood scales. The researchers interpreted spatial patterns of UGI from 2000 to 2019 using Google Earth Engine (GEE), used landscape pattern indices and Morphological Spatial Pattern Analysis to quantify the changes in UGI landscape patterns over the 20 years, and then used various regression models to reveal the statistical relationship between UGI landscape patterns and PM_2.5 concentrations. 

The researchers found that at the scale of urban agglomeration, the annual variations in PM_2.5 concentration were mainly attributed to economic development, urbanisation and other socio-economic factors, and meteorological factors such as wind speed and relative humidity had greater effects on PM_2.5 concentration than UGI landscape pattern factors. At the neighbourhood scale, the relationship between UGI landscape pattern and PM_2.5 pollution changed with neighbourhood spaces and seasons, showing scale and seasonal effects.  

In addition, the researchers found that the impacts of UGI landscape patterns on PM_2.5 were greater at the neighbourhood scale than those at the urban agglomeration scale. 

The results of this study deepen the understanding of the relationship between UGI landscape patterns and PM_2.5 concentrations, which will provide a scientific guidance for future urban planning and the prevention and control of PM_2.5 pollution. 

This study, funded by the National Natural Science Foundation of China and the Youth Promotion Association of the Chinese Academy of Sciences, has been published in Journal of Cleaner Production, titled "Multiscale analysis of the effects of urban green infrastructure landscape patterns on PM2.5 concentrations in an area of rapid urbanization."