GIS-Based Urban Afforestation Spatial Patterns and a Strategy for PM2.5 Removal

Abstract

Within the scope of ecological development planning in China, afforestation is highly valued. However, the scientific planning of afforestation still has inadequacies. There are few studies on the spatial distribution of urban forests targeted at air quality improvement. Here, we implemented a virtual experiment to evaluate whether different tree planting distribution plans with the same afforestation scale would have a significant effect on fine particulate matter (PM2.5) removal. As a case study of Wuhan, this paper identified the statistical regularity between PM2.5 concentration and adsorption of representative trees through field sampling and measurement, simulated the influence of different afforestation plans on PM2.5 concentration based on Geographic Information System (GIS), judged the significance of the difference of the plans, and proposed a greening distribution strategy. The results show that different forest layouts had no significant impact on PM2.5 in the administrative region, and the concentration reduction rate was only 1%–2%. Targeted planting of trees in heavily polluted areas in the city center would have achieved better air quality improvement, with a reduction rate of 3%–5%. In Wuhan construction areas, trees should be planted to increase the forest coverage rate to 30%. The edge of the urban metropolitan development zone needs to be strengthened with trees to form a forest belt 10 km–20 km wide, with a forest coverage rate of at least 60%. In general, the capability of trees to reduce PM2.5 concentration is weak. The fundamental way to improve air quality is to reduce emissions; planting trees is only an auxiliary measure. More ecological forest functions should be considered in city-wide afforestation distribution.

Diversified responses of vegetation carbon uptake to urbanization: a national-scale analysis

“…As a direct outcome from urbanization, reduced vegetation coverage in many cities was reported . The country has long proposed policies to underpin green urban development paths, including urban afforestation or other urban vegetation protection programs (Zhou et al, 2019a). The selected cities cover a broad range of urbanization pathways because of differences in natural environments, resources, and socio-economic development and thus allow us to find different patterns in the impact from urbanization on vegetation carbon sequestration.…”

“…This finding suggests that vegetation carbon sequestration in urban area could be a complicated ecological process, which is not solely associated with the loss of vegetation cover. For example, some cities in China have paid more attention to urban greenness restoration than others, and thus, urban greenness was better protected in urban areas through urban and community protection programs (Zhou et al, 2019a). On the contrary, degraded vegetation productivity could be significant due to lack of effective urban planning and vegetation management measures (Rimal et al, 2018).…”

Simulation of the Impact of Urban Forest Scale on PM2.5 and PM10 based on System Dynamics

“…A previous study we conducted, "GIS-Based Urban Afforestation Spatial Pattern and a Strategy for PM 2.5 Removal," explored the impact of different distributions of newly added forests in Wuhan on PM 2.5 and proposed suggestions [46]. One conclusion was that it is of limited significance to consider the forest distribution in city's whole administrative region with the same scale of afforestation.…”