Incorporating ecology in urban planning and design
Consideration of urban ecosystems and their ecology in urban planning and design is important for ensuring that urban regions maintain as high an environmental quality as possible. This in turn means that they may be more sustainable, with an enhanced capacity to provide ecosystem services, as well as making them more pleasurable environments in which to reside. There has always been an element of integrating nature into urbanisation, but as both urbanisation and ecological awareness have increased in recent decades, the objectives, principles and techniques applied to urban planning and design have changed. Urban planning usually relates to longer-term strategies and policies relating to land-use change across broad spatial areas, while design is short-term, ﬁne-scale implementation of land-use change or modiﬁcation, though the two are clearly interrelated and in many cases the terms are used somewhat interchangeably. Both are considered in this chapter. The intentional preservation of vegetated areas from urban development, and in
some the cases the speciﬁc creation of greenery in semi-arid areas through manipulation of water resources, has taken place since antiquity. Persian and Roman cities, for example, had both private and public parks and gardens (Gleason, 1994; Faghih and Sadeghy, 2012). These early green spaces were not created for ecological purposes but rather for recreation, aesthetics, to provide water and shade, for religious or spiritual matters, or sometimes in order to demonstrate power and wealth. These broad aims have generally remained the focus of urban planning and design, and it is only relatively recently that ecological considerations have emerged. For example, the urban parks movement that began in the nineteenth century and led to the development of major urban parks around the world (Harnik, 2006) was instigated out of a desire to improve the living environment for citizens, rather than to safeguard ecosystems or species – such concerns not having entered the public consciousness at that time. Likewise, the notion of ‘garden cities’ espoused by Ebenezer Howard at the end of the nineteenth century (Howard, 1898), involving the creation of deﬁned urban regions with planned green space and contained within a green belt, was aimed at melding rural and urban ideals to create pleasant and healthy living environments for citizens. Even some of the most signiﬁcant planning instruments that have helped to preserve
green space within urban regions were not speciﬁcally intended to have ecological beneﬁts. An example is the green belt, which has been a major tool for urban planning since the late nineteenth century. This is a contiguous boundary of green space
encircling an urban complex, usually composed of natural or semi-natural vegetation mixed with agricultural land and commercial forest plantations. The green belt concept was proposed principally to contain urban expansion, and to ensure a distinction between ‘rural’ and ‘urban’ regions (Amati, 2008). As a formal planning tool, it was ﬁrst developed in the UK (Figure 8.1), though the principles of preserving exurban
green space were established in many other locations (e.g. across Europe and the USA) in the early twentieth century (Ignatieva et al., 2011). The UK model was applied throughout the world, with varying success, until the 1970s. By this time the limitations of green belts in halting expansion had become more apparent. As with most green space, green belts were also intended to provide opportunities for recreation, particularly where green space was lacking within the urban complex itself. They were certainly not designed to preserve space for biodiversity (this mainly being a recognised concern from the 1980s onwards), though they have since become important for many species as surrounding areas have been degraded. This is reﬂected in the observation that much of the land used for early green belts consisted of former estates, farms, common land and golf courses (Amati, 2008) rather than land that was ecologically ‘valuable’ or natural, and also in the gradual urban encroachment that often occurs on green belts (Amati and Yokohari, 2006). More recently, planning for green space and urban ecology has questioned the divide between urban and nonurban spaces, and has followed the path of spatially integrated ‘greenways’, ‘green corridors’ or ‘green networks’ that weave through the urban region rather than encase it. Much of this has developed from the principles of landscape ecology considered in Chapter 2 (particularly landscape connectivity), and is considered here in more detail. Recognition of the ecological beneﬁts of urban green space is a recent development,
as is the incorporation of green space preservation or restoration in urban planning speciﬁcally to support biodiversity and urban sustainability. Despite an increasing focus on ecologically sensitive urban development, the design of green spaces and networks, and the potential for ecological and environmental engineering of urban environments, rigorous spatial planning for urban ecology remains a nascent ﬁeld for both implementation and scientiﬁc investigation. This chapter ﬁrst considers the role of planning in ecologically sensitive urbanisation that aims to minimise biodiversity impacts and preserve green space. It then considers the incorporation of ecological principles into green space planning and design, and the spatial planning of green networks. Finally, there has more recently been an awakening of the possibilities of ecological and environmental engineering, particularly of the built environment, in order to provide habitat for species within the urban environment, but also to mitigate some of the environmental problems that plague urban ecosystems. This aspect of urban planning and design is also brieﬂy considered.