Ecological Modelling 220 (2009) 3612–3620

Ecological Modelling 220 (2009) 3612–3620 Contents lists available at ScienceDirect Ecological Modelling journal homepage: www.elsevier.com/locate/ecolmodel Urban ecological security assessment and forecasting, based on a cellular automata model: A case study of Guangzhou, Chinaଝ Jian-zhou Gong a,b, Yan-sui Liu b, Bei-cheng Xia c, Guan-wei Zhao a,∗ a School of Geographical Sciences, Guangzhou University, Guangzhou 510006, China b Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China c School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, China article info abstract Article history: Forecasting changes in urban ecological security could be important for the maintenance or improvement Available online 11 November 2009 of the urban ecological environment. However, there are few references in this field and no landmark research work has been reported, particularly quantitative research. A forecasting model for ecological Keywords: security based on cellular automata (CA) was developed using preliminary spatial data from an ecological Urban ecological security security assessment of Guangzhou conducted previously (1990–2005). The model was constrained using Assessment transformation rules based upon proposed planning for 2010–2020. A simulation accuracy of 72.09% was Forecasting acquired. Using a one-bit assessment grid for 2005 as the starting state for the simulation, the model CA Guangzhou was used to forecast ecological security for 2020. This revealed that although the ecological security status would be improved relative to current trends, there would still be an overall decline in ecological security over the next 15 years. Even if new urban plans were implemented, landscape pattern analy- sis suggested a more scattered and homogenous distribution in the urban landscape of Guangzhou and significant variation in landscape characteristics among districts. This suggests that further measures must be adopted to reverse the current trends in Guangzhou’s ecological security. The model highlights the need to make ecological protection an integral part of urban planning. This study demonstrates the potential of CA models for forecasting ecological security. Such models could make an important contribu- tion to decision-making for regional governors and to the development of urban planning incorporating assessment and prediction of ecological security. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Traditionally the concept of security denotes safety from injury, harm, or danger, and in most cases it infers no damage to the life, Since the industrial revolution, humans have notably created health, property or territory of a region or nation. Many existing and and been impacted by a variety of forms of pollution and ecosystem potential problems (economic, ecological and social) are consid- degradation. Nevertheless, until recently much of this ecosystem ered within problems of security. Moreover, ecological security has degradation has been ignored (Shi et al., 2006). In the middle of the been linked with national security, economic security and human last century, concerns began to mount over problems caused by well-being (Edward, 2002). ecological degradation, and regional and global ecological security The term ecological security was first proposed by the gov- has become a common interest of many countries and organiza- ernment of the United States (Ezeonu and Ezeonu, 2000). Since tions. At the Johannesburg 2002 World Summit on Sustainable then, although it has been widely considered (Solovjova, 1999; Development participating countries shared a common concern Kullenberg, 2002; Ma et al., 2004), a universally accepted defi- over ecological security. Ecological security was also clearly named nition has not been agreed upon, nor have standard assessment as a fundamental component of state security. parameters or research methods been accepted (Zhao et al., 2006). Ecological security is temporally dynamic and has spatial structure and thus any study must embrace these dynamics. Feedback of ଝ assessment results to support decision-making for planning future The study was supported by the following foundations: The National Natural Science Foundation of China (No.40635029); The National Science Foundation for developments is also desirable. Ecological security modeling may Post-doctoral Scientists of China (No. 20080440511); Science & Technology Project fulfill these criteria and provide useful insight. Nevertheless, there of Guangzhou (No. 08C027). ∗ is lack of prior or similar studies to inform the choice of method. Corresponding author at: Box No. 126A, No. 230 Waihuanxi Road, University Urbanization has profoundly changed land use and thus land Town, Panyu District, Guangzhou, Guangdong Province, China. Tel.: +86 20 34156412; fax: +86 20 39366890. cover around the globe (Courage et al., 2008; Long et al., 2009). E-mail address: [email protected] (G.-w. Zhao). Many ecological and environmental problems are thought to result 0304-3800/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.ecolmodel.2009.10.018 J.-z. Gong et al. / Ecological Modelling 220 (2009) 3612–3620 3613 from land use cover change (LUCC) (Meyer and Turner, 1992; tions. Geographical studies have developed CA models to represent Stephan et al., 2005; Stevens et al., 2007). Thus urban/regional plans spatial and time-dependent processes of complex systems, such as ought to support sustainable development and promote ecologi- forest dynamics or planning (Lett et al., 1999; Anne-Hélène et al., cal security. Existing as well as newly introduced environmental 2008), urban growth (Dragicevie et al., 2007) and land use change problems need to be incorporated into urban development plans (Stevens et al., 2007). such that ecological security is a priority in any acceptable urban Ecological security theory informs us that the internal structure development scheme. As a consequence, urban growth plans, their of ecosystems is logical and stable and that the service func- resulting spatial impact and their associated forcing factors, have tion of ecosystems is positive and tends towards health (Liao et become key areas of planning and urbanization research (Batty al., 2004). Like other complex geo-phenomena, ecological secu- and Xie, 1994; Al-Ahmadi et al., 2008). Methods to assess urban rity includes many complex processes, is typically space- and planning and resultant growth scenarios as well as to forecast the time-dependent and is affected by the states of neighboring areas resultant urban ecological security are an absolutely requirement and relative social-natural factors. Thus, CA may be particularly for sustainable development of an area. However, relevant research suitable for investigating ecological security, but there are no is limited, and few studies have investigated forecasting ecological prior applications of CA models for the assessment of ecological security during urbanization. Thus the question of how ecological security. security for a particular region should be determined is open to dis- Guangzhou is a rapidly developing super megalopolis. Its eco- cussion. Here, quantitative models to describe regional ecological logical security has been assessed for the past 20 years (Gong and security could be helpful. Xia, 2008a,b). In this study an urban ecological security CA model In cellular automata (CA) models local interactions reflect global was developed by coupling an ecological security assessment properties and determine the evolution of system. These models are model with a CA framework model, and the ecological security of discrete both in space and time (White and Engelen, 1997; Lena Guangzhou was taken as a case study. There were two phases to and Margara, 2008) employing regular two-dimensional lattices this investigation. First, the urban ecological system of Guangzhou such as grids (Fonstad, 2006). Generally, CA models are charac- for 2005 was simulated and compared with ecological security terized by a matrix space, where each cell possesses a state. Time assessment results for 2005 obtained from prior studies, thus the is discrete and progresses through iterations. With each iteration parameters of the model were regulated. Second, the model was cell transition rules are applied which redefine cell states (André used to forecast the future ecological security for 2020. and Danielle, 2007). Transition rules describe functions of a series The primary objective was to couple CA with ecological security of independent variables on the dependent variable (cell state). assessment to identify insecure cells within the region and simu- Thus CA models have an immense capacity to simulate complex late their future development. At minimum, this provides another processes or systems through building and applying different func- view of ecological security and some suggestions for urban plan- Fig. 1. The study area. 3614 J.-z. Gong et al. / Ecological Modelling 220 (2009) 3612–3620 ning. Potentially, its findings could prompt improvements in the 3. A CA model for ecological security forecasting of urban ecological environment, as well as inform new planning for Guangzhou Guangzhou in the next decade. 3.1. Motivation 2. Urban ecological security history and status and urban planning for Guangzhou The latest Guangzhou comprehensive master plan was pub- lished in 2008, and a major goal was to direct further urban Guangzhou (Fig. 1), the biggest megalopolis

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