استفاده از مدل ترکیبی چشم انداز پایدار برای ارزیابی کیفیت فضاهای عمومی طبیعی (فضا های سبز شهری): مطالعه موردی از رودخانه های تهران Using the Component Model of Sustainable Landscape for the Quality Assessment of Urban Natural Public Spaces: A Case Study from Tehran’s River-valleys

INTRODUCTION Tehran is located in a plain between Alborz Mountains and the northern border of the Central Desert of Iran. Among the geographical features of Tehran’s landscape are the foothill areas at the north, which are of high ecological importance in terms of water resources, plantation and mountain climate. Environmental conditions of these regions directly influence Tehran’s landscape. Any ecological damage or the pollution of these areas has direct consequences for the rest of the landscape. Changes in the use of environment and natural corridors of these regions and in general any land structure whose biological function is defined to be the origin of landscape ecological services is the main concern of Tehran’s landscape planning to maintain and improve its ecological, urban and societal quality. In order to evaluate the quality of Tehran’s urban public spaces resulting from the recreation of urban natural environments, we need to provide a conceptual model with comprehensive components and criteria, with which the quality of urban natural public spaces can be assessed. Accurate evaluation of urban natural public spaces and an assessment of their current deficiencies will help towards the development of highly qualified urban environment. By scrutinizing existing conceptual models, the study provides a new conceptual model to assess the quality of Tehran’s river-valleys’ natural environments (Fig. 1). In planning for urban natural environment, we need to look at a multilateral management of landscape and human activities from an urban landscape point of view, referring to a geographical unit characterized by a specific pattern of ecosystem type and formed by interactions of geographical, ecological and human-induced forces (Forman, 1995; Steiner, 2000). Mentioned by Linehan and Gross (1998), landscapes change, form and transform anthropocentrically. Every human activity, such as building the environment, takes place in one or more ecosystems. Establishment and continual sustainability of complex environmental ecosystems requires coexistence and balanced relations of their elements with each other and also with larger environments. Opdam refers to landscape as a unit of planning, with considerable attention paid to human activities that influence the transformation and dynamics of the ecological balance (Opdam et al., 2006). Since natural environments are heritage of our cities and their maintenance and protection is necessary for continuation of urban life, it is very important to give special attention to the principles of landscape ecology in a model provided for investigating the quality of urban natural public spaces. Landscape ecology focuses on structures, functions and transformations of the environment, attempting to find patterns and interactions between landscape elements, patches, corridors and the matrix (Forman, 1995; Ingeognoli, 2002). As any urban ecosystem consists of a whole set of landscapes that are more or less sustainable, any planning and design strategy, especially in large scale landscapes, should consider the principles of ecological networks to integrate ecology into sustainable land development. These are the reasons that necessitate the proposal of a comprehensive component model for investigating the quality of urban public spaces that have been born out of regenerating urban natural environments. By analyzing existing component models, this study has attempted to provide a comprehensive component model for the application of landscape ecology principles to the regeneration process of urban natural environments and the continuous process of sustaining ecosystem, environment and human interactions in urban natural public spaces. In providing a new comprehensive model, the integration of the fundamental concepts for the evaluation of the quality of space used by models such as PPS (Project for Public Spaces) (Fig. 2), CABE Space (Commission for Architecture and the Built Environment) (Table 1), and Socio-spatial Sustainability (Maghsoudi, 2007) (Table 2) has been implemented. PPS is the result of investigating the quality of urban spaces in more than 1000 public spaces; CABE Space is a proposed model with a prominent comprehensive idea in order to create public spaces with a high standard of quality and value; and Sociospatial Sustainability gives a conclusion for the collective ideas of modernism, formalism, radicalism and naturalism to urban planning specialists in order to analyze the quality of urban public spaces. In these models the necessity of landscape ecology principles for evaluating the interconnecting process of social and natural systems is identifiable: PPS is planning oriented; CABE Space ignores many criteria; and Sociospatial Sustainability only considers the timeframe of project construction, while disregarding the value of spatial built systems. For introducing the component model of Sustainable Landscape, in the level of system ecology, aspects of nature and bio system on the one hand, and manmade program and idea system on the other hand, are identifiable. By their mutual interactions, components of ecological structure, ecological function, thought structure and ecological equilibrium are definable (Fig. 3 and Fig. 4). In the level of urban ecology, aspects of environment and built system on the one hand, and human activity and form system on the other hand, are identifiable. By their mutual interactions, components of spatial structure, environmental function, mold structure and environment sustainability are definable (Fig. 3 and Fig. 4). And finally, in the level of human ecology, aspects of landscape and human system on the one hand, and social behavior and ideal system on the other hand, are identifiable and by their mutual interactions, components of social structure, social function, meaning structure and social excellence are definable (Fig. 3 and Fig. 4).