Journal of Environmental Management 88 (2008) 665–676 Assessing the ecosystem service of air pollutant removal by urban trees in Guangzhou (China) C.Y. Jim à , Wendy Y. Chen Department of Geography, The University of Hong Kong, Pokfulam Road, Hong Kong Received 23 July 2005; received in revised form 28 January 2007; accepted 19 March 2007 Available online 17 May 2007 Abstract In Chinese cities, air pollution has become a serious and aggravating environmental problem undermining the sustainability of urban ecosystems and the quality of urban life. Besides technical solutions to abate air pollution, urban vegetation is increasingly recognized as an alternative ameliorative method by removing some pollutants mainly through dry deposition process. This paper assesses the capability and monetary value of this ecosystem service in Guangzhou city in South China. The results indicated an annual removal of SO 2 , NO 2 and total suspended particulates at about 312.03 Mg, and the benefits were valued at RMB90.19 thousand (US$1.00 ¼ RMB8.26). More removal was realized by recreational land use due to a higher tree cover. Higher concentration of pollutants in the dry winter months induced more removal. The lower cost of pollution abatement in China generated a relatively subdued monetary value of this environmental benefit in comparison with developed countries. Younger districts with more extensive urban trees stripped more pollutants from the air, and this capacity was anticipated to increase further as their trees gradually reach final dimensions and establish a greater tree cover. Tree cover and pollutant concentration constitute the main factors in pollutant removal by urban trees. The efficiency of atmospheric cleansing by trees in congested Chinese cities could be improved by planting more trees other than shrubs or grass, diversifying species composition and biomass structure, and providing sound green space management. The implications for greenery design were discussed with a view to maximizing this ecosystem service in Chinese cities and other developing metropolises. r 2007 Elsevier Ltd. All rights reserved. Keywords: Air pollution; Ecosystem service; Green space; Monetary value; Non-market commodity; Sustainable development; Urban ecology; Urban forest; Urban tree; Guangzhou; China 1. Introduction Air pollution has become a serious environmental problem affecting human health, quality of urban life and sustainability of urban ecosystems, particularly in cities of developing countries (UNEP, 1997, 2002, 2005; Kojima and Lovei, 2001; Fenn et al., 2002). Recently in China, the rapid urbanization, industrialization and rural–urban migration have contributed to decline in air quality (Chang et al., 1998). Air pollution has become pervasive and acute in major metropolises such as Guangzhou in south China, and it augurs ill if the current fast-growing trends continue (Chen and Bao, 1994; Faiz and Sturm, 2002). The management of urban air quality is by necessity a multidimensional issue. Besides the application of ad- vanced technologies in prevention and amelioration, the option of employing natural mechanisms to effect ecolo- gical abatement is occasionally adopted by design but commonly contributes by default. In this regard, the air cleansing capacity of urban trees presents an alternative approach to foster an integrated approach to the sustain- able management of urban ecosystems (Nowak et al., 2002, 2006; Randolph, 2004). Besides beautifying urban landscapes, trees in urban green spaces can significantly improve urban air quality (Grey and Deneke, 1986; Nowak, 1994; MacDonald, 1996; Miller, 1997; Luley, 1998; McPherson et al., 1997, 1998, 1999; Nowak et al., 1998, 2006). The removal of air pollutants, such as sulfur dioxide (SO 2 ), nitrogen oxides ARTICLE IN PRESS www.elsevier.com/locate/jenvman 0301-4797/$ - see front matter r 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.jenvman.2007.03.035 à Corresponding author. Tel.: +852 2859 7020; fax: +852 2559 8994. E-mail address: hragjcy@hkucc.hku.hk (C.Y. Jim).