“Cities can become more sustainable by modeling urban processes on ecological principles of form and function, by which natural ecosystems operate. The characteristics of natural ecosystems include diversity, adaptiveness, interconnectedness, resilience, regenerative capacity, and symbiosis.” (Newman and Jennings 2008)
City as a regenerative and symbiosis system
The core philosophy of sustainability lies in the appreciation of nature as the symbol of integrity, stability and beauty. Sustainability deals much with creative designs and planning in harmony with nature. From the perspective of sustainability, nature’s design and technologies are far superior to human science and technology (Sterry 2010).
In nature, nothing is useless, nothing is waste but everything is resource for other process in the sophisticatedly interconnected web of life, where circular metabolism is the principle of ongoing self-renewal system. Thus, a sustainable system is a regenerative system that mimics nature’s circular patterns, replacing the present linear flows with cyclical flows.
On a predominantly urban planet, cities will need to adopt circular metabolic systems to assure their own long-term viability as well as that of the rural environments on which they depend; outputs will need to become inputs into the local and regional production system (Girardet 2010). Most importantly, it is crucial to return organic waste into plant nutrients, for assuring farmland’s long-term fertility. By recycling wastes back into the system, it also minimizes pollution. Sustainably using renewable resources, instead of fossil fuels and chemicals is also more resource-conserving, healthy and less environmentally damaging.
On the other hand, creating a circular urban metabolism can create resilient cities and create many new local businesses and jobs (Girardet 2010). About resilience, Melissa Sterry is developing the model of Bionic City[1], which embraces nature’s approach to building complex infrastructures: “Whereas the conventional city is a mass of static, disconnected and inert structures operating independently and irrespective of one another and their environment, the Bionic City operates as an interconnected and intelligent ecosystem in which every entity is engaged in an ongoing symbiotic relationship with all others, from the molecular to the metropolitan in scale. Beyond preventing the problems traditionally associated with flooding, the Bionic City will also feature the means to utilise excessive quantities of water, including hydropower and water harvesting technologies.” According to Melissa Sterry, the sensitivity the city has with its surroundings is key to its ability to predict and prepare for environmental changes.
One essential characteristic of nature systems that helps maintaining stability in constantly changing conditions is diversity (Holmgren 2002). Multiple associations nurture each life form, thereby increasing the stability and resilience of the whole system. In natural system, everything is connected to everything else, each important function is supported by many elements, and each element performs many functions. Thus, this provides the thinking of multiple pathways to achieve one goal as well as a common solution to disparate problems (Lyle 1994). For instance, rainwater infiltration with thoughtful design can replenish groundwater, create landscape, as well as reduce urban flooding…
The idea of solving problems simultaneously is also the main theme of SymbioCity[2], an urban sustainability approach by Sweden. Symbiosis means the integration of two or more organisms in a mutually beneficial union. Looking at the city as a whole, we find benefits through synergies in urban functions such as combination of industrial waste heat with the municipal energy plant, combination of architecture and landscape planning…
SymbioCity means urban resource efficiency – across and between different urban technological systems, letting nothing go to waste; combining energy, waste management, water supply and sanitation, traffic and transport, landscape planning, architecture and urban functions for new and better solutions as well as a more efficient use of natural resource (SymbioCity 2009).
There are many ways to make an urban function effective, but focusing on them individually may let us miss out the synergies between them, which can only be found with a holistic approach. Therefore, an integrated planning approach is key to unlocking hidden synergies in the city. Instead of managing urban sectors one by one, SymbioCity combine them, saving valuable city resources and creating new values (SymbioCity 2009).
Urban ecology and integrated land use
As the spirit of sustainability lies in the heart of nature, protecting and restoring ecology within urban areas, bringing nature back into city is an essential theme in urban sustainability. Green spaces in cities offer us a lot of benefits. They provide shading, filtering the air, enriching urban biodiversity, reducing urban heat island effect, thus simultaneously making bioclimate comfort and lowering energy use for cooling. “Urban ecology uses climate- and region-appropriate plants, xeriscaping[3] to minimize the need for fertilizer and water, and uses land for multiple functions such as food production, wildlife habitat, recreation and beautification” (Roseland 2005). Urban ecology also acknowledges the role of water and urban aquatic systems – streams, ponds, rivers in revitalizing cities. Besides those ecological advantages, thoughtful urban designs in concert with nature and embracing culture of a place also have many aesthetic values, social and psychological healing benefits. Green public spaces can enhance community connection and interaction, providing places to contemplate, play, relax and meditate.
Since land use permeates nearly all urban aspects, appropriate land use is a decisive factor for a sustainable city. In order to be sustainable, city should minimize land consumption, integrating green spaces and preserving farm land for food security as well as for other ecological functions. It is not always easy as land is a limited resource and the cost of real estates is often too high, while cities have to balance among conflicts of urbanization, development, population pressure with environmental and social goals. Therefore, symbiosis integrating planning or whole systems design[4] for multi-purpose use can help afford this balance. Many examples illustrate this concept (Roseland 2005): green roof, solar photovoltaic panel on rooftop (no extra space needed); parks, urban gardening as both recreation areas and edible landscaping; constructed wetlands as sewage treatment facility, natural habitats, recreation areas, drainage for rainwater run off…
Urban agriculture
Urban agriculture or urban farming can be understood as farming within and around cities. “Urban agriculture is a dynamic concept that comprises of a variety of farming systems, ranging from subsistence production and processing at household level to fully commercialized agriculture” (Zeeuw et al. n.d.).
Urban agriculture as a tool for sustainable urban development
(adapted from Zeeuw)
(adapted from Zeeuw)
In response to serious problems of poverty, food insecurity, and environmental degradation, there is a growing attention and promotion of urban farming all over the world, along with the movement of resilient, self-sustaining and low carbon cities. Increasingly, urban farming has been seen as part of sustainable urban development.
Urban farming can contribute to a food secure and inclusive city, a productive and environmentally healthy city (fig. 3.5). Therefore, it is necessary to acknowledge the links between urban agriculture and various policy target areas, such as the alleviation of poverty, economic development, or environmental protection, in order to justify the inclusion and mainstreaming of urban agriculture into municipal policies and public support programs (Zeeuw et al. n.d.).
The most striking feature of urban farming, which distinguishes it from rural agriculture, is its integration into the urban economic and ecological system (RUAF)[5]. Urban farms and gardens complement rural agriculture in local food systems and can also become an important income supplement for households. Since food production is close to home and market, it helps reduce energy for transportation and packaging costs. This is also helpful in situations when supply chains from rural areas have been interrupted and cities are unable to receive food imports (Worldwatch 2011). Another essential benefit of urban agriculture is that it can contribute to waste management and nutrient recycling by turning urban wastes into a productive resource, thus reducing the use of expensive chemical fertilizers and improving local soil fertility (Veenhuizen and Danso 2007).
In his theory of Food Urbanism (2009), Jason Grimm showed that urban food system of production, processing, distribution, marketing, consumption and waste management can become infrastructure that transforms urban experience by thoughtful sensitive design and planning. According to Grimm, food production can be integrated into the daily activities of community residents through recreation and communal gatherings. Community gardens can also provide beautiful and pleasing spaces, helping improve the air quality in urban areas. And through cooperative market outlets, a larger series of food access points can be developed, supplying healthy fresh and affordable food.
[1] “Bionic City”- article on Earth 2.0 magazine: http://earth2channel.com/magazine/article/22
[2] More on SymbioCity: http://www.symbiocity.org
[3] Xeriscaping refers to landscaping and gardening in ways that reduce or eliminate the need for supplemental water from irrigation
[4] Whole systems design concept for sustainability: http://www.wholesystemsdesign.com
[5] RUAF – Resource Centres on Urban Agriculture & Food Security: What is urban agriculture? http://www.ruaf.org/node/512
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