Ecological infrastructure is an integrated approach to urban design bringing together landscape design, ecological planning, engineering, community participation, etc., to solve urban environmental problems (such as flooding) and to protect natural ecosystems from the pressures of urbanization. “It combines grey and green infrastructure at an ecosystem scale and emphasizes the coordination of each component and the maximization of multiple system functions, instead of the function of single component” (Li et al., 2017).

 

Ecological infrastructure (EI) focuses on systems thinking (eg. natural, semi-natural and low impact systems) and developing means of accounting for the EI benefits through ecological services. Ecosystem services include a wide range of benefits including:

• The improvement of air and water quality and supply

• Soil fertility

• Biodiversity

• The mitigation of disturbances such as flooding or landslides

• The creation of livable microclimates

• The provision of biophilic activities

• Providing for potential cultural and recreational activities, etc. 

(Firehock, 2015)

 

According to Hester and Harrison (2010): “Ecosystem services are the benefits humankind derives from the workings of the natural world. These include most obviously the supply of food, fuels and materials, but also more basic processes such as the formation of soils and the control and purification of water, and intangible ones such as amenity, recreation and aesthetics”. Ecosystem services are often divided into categories, such as supporting services, regulating services, provisioning services, and cultural services, all of which have subcategories and their own definitions. There are specific approaches and new infrastructures that target specific services, such as green corridors, wetlands, bioswales, green roofs, urban forests, and more. 

 

The increasing amount of urban problems such as flooding, air pollution, and traffic pollution have highlighted just how inadequate infrastructure is to cope with changing factors, emphasizing designing infrastructure that is more able to adapt and be resilient (Li et al., 2017). Designers have started to think about how to approach these issues; “urban forests, parks, woodlands, green roofs, wetlands, rivers and others natural spaces play key roles in enhancing urban ecosystem services, improving urban environments, combating climate change, and maintaining ecological balance” (Ibid). We have seen a surge in adding more green space to cities, an approach that has allowed cities to begin rehabilitating and improve the well-being of city dwellers. Studies have shown that increasing green space (such as green roofs, permeable pavement, and sunken green space) can reduce runoff significantly, in addition to providing cost-effective solutions that require less on-going maintenance (Ibid.). Moreover, urban ecological infrastructure attempts to create or preserve the ecosystem services that we need to survive. Specifically, these urban-scale techniques function to supply water, recycling, energy, heat dissipation, soil fertility, biodiversity, material metabolism, waste regeneration, runoff reduction, nutrient retention, and provision of cultural services (Ibid.). 

 

Ecological infrastructure aims to positively impact the daily lives of humans, animals as well as rehabilitating or conserving nature. Andrews, Nanjappa, and Riley (2015) define ecological infrastructure as “the basic habitat components and their connections necessary for species survival, and for natural populations, communities and ecosystems to function properly”. By combining this definition with many others, we can see that the entire premise of ecological infrastructure is to find ways in which infrastructure networks provide ecosystem services and sustainable urban systems rather than jeopardizing them (Li et al., 2017).

 

Ecological infrastructure requires system thinking where elements of an ecological urban system typically provide multiple benefits, as opposed to single functions of traditional infrastructure. When developing strategies of urban design. Urban design strategies are often about considering multiple systems. Ecological infrastructure is about the integration of systems. Systems under consideration when developing urban design strategies include:

• The habitat system - addresses the preservation and restoration of functioning habitat (support life/ human contact)

• The hydrological system - the flow and distribution of water (green stormwaterinfrastructure, harvesting clean water)

• The active transport system - transportation systems including cycling and walking(human health as ecosystem service)

• The metabolic system - the processes and elements that provide energy, nourishpopulations, neutralize toxins (soils) and transform waste into useable nutrients.

• Community and open space system - diverse public open spaces that improve livabilityand connect people to one another.

 

In recent years, there has been a focus on shifting from managing these components separately to managing them as one integrated system (Andrews et al., 2015). Ecosystem services act as a means of accounting for the costs and benefits associated with integrated systems. Another way of thinking about ecological infrastructure is through the assemblages of landscape structure and landscape processes. “A comprehensive understanding of the inner workings of the landscape requires us to look at it in terms of structure, process, and location. By structure, I mean the composition of biological and nonliving elements in natural and human environments – the functional relationship between elements such as climate, landforms, soils, flora, and fauna. Process implies the movement of energy, materials, and organisms in the landscape, location refers to the distribution of elements and processes in the landscape in relation to climate and landforms (Ndubisi, Thompson, & Steiner, "Landscape Ecological Planning", 1997, pp. 25-26). Cities may be considered in term of how the landscape structure has been modified, buildings and hard surfaces replacing living and naturally occurring elements; in terms of how processes have been disturbed and or supplanted; and how the heterogenous distribution of natural elements has been replaced by building and surface types. Ecological urban infrastructure strategies seek to retain or reintroduce natural structure and processes in/into the urban mosaic.

 

Ecological urban infrastructure may be understood through concepts derived from Landscape Ecology such as patches, corridors, and matrices. The urban landscape may be considered in terms of how development has isolated natural ecological patches, broken corridors necessary for the flow of energy, matter and species, or disrupted the consistent ecological matrix.  “Landscape ecology provides a conceptual framework within which planners and designers can explore how the structure of land evolves along with relevant ecological processes. If landscape is the interface between human and natural processes, by implication landscape ecology focuses on the medium in which the dialogue between both processes occurs. Landscape ecology also regards the landscape as an interacting mosaic of ecosystems, connected by flows of energy and materials. Over time, the ecosystems develop an identifiable visual and cultural identity” (Ndubisi, Thompson, & Steiner, "Landscape Ecological Planning", 1997, pp. 32). Ecological Urban Infrastructure attempts to integrate non-human and human systems.