City Biodiversity and the development of 'Green Urbanism'

As previously suggested we have entered a new geological epoch called the ‘Anthropocene’ where the cumulative impacts of billions of people are being experienced. The impacts are so extreme that we are now disrupting this steady state life system through climate change, toxic air pollution, biodiversity collapse and social inequality (Partington, 2013) Recently, there has been a lot of  discussion in scientific literature surrounding biodiversity and urbanization, especially relating to city biodiversity. Urbanisation is the physical growth of urban areas as a result of global change. With a booming human population, city biodiversity is set to become a major factor in our increasingly interconnected world. The Convention on Biological Diversity (2011) stated that by 2050, almost 3 billion additional people will inhabit the world’s cities and the world will have undergone the largest and fastest period of urban expansion in all of human history. A recent estimate reveals that the area directly impacted by new urban infrastructure within the next 40 years will roughly cover an area the size of Mongolia, with obvious impacts on the natural habitat. Consequently, urban growth will impact the provision of many ecosystem services and the demands of cities will reshape most rural landscapes in the coming decades.

Map showing the transport links of humanity and the interconnectivity of the globe.

One way urbanisation can cause disturbance to biodiversity is through habitat loss (Czech et al. 2000). It is often cited as the primary cause of species endangerment in the United States. As can be seen in the table below, urbanisation caused 275 endangered species in United States and Puerto Rico (Czech et al. 2000). The only human impact that tops urban development is non-native species disturbance. Czech (2004) states that urbanisation is one type of habitat loss and that this anthropogenic implication can transform the “economy of nature” to the human economy. In some cases of habitat loss, natural capital is simply cleared away to make room for human economic infrastructure and enterprises. 

It is not just cities that will have an increasing human population, infact most of the urban expansion is predicted to occur in medium to small urban areas of low economic capacity. Since urbanisation is changing the nature of our planet, preserving biodiversity on this urban world requires going well beyond the traditional conservation approaches of protecting and restoring what we think of as “natural ecosystems,” and trying to infuse such elements in the design of urban spaces (Convention on Biological Diversity Report, 2011). The report also states that 

‘cities already represent a new class of ecosystems shaped by the dynamic interactions between ecological and social systems. As we project the spread of these ecosystems across the globe, we must become more proactive in trying not only to preserve components of earlier ecosystems that they displace, but in imagining and building entirely new kinds of ecosystems that allow for a reconciliation between human development and biodiversity’.

It is refreshing to hear that people are accepting urbanisation and its affect on biodiversity, including trying to think creatively about new spaces in the city to encourage species diversity. While we know that urbanisation, through habitat loss, can displace many species it becomes vital to understand that some species have infact evolved adaptive responses to thrive under urban pressures. Some endangered species find suitable habitats in urban ecosystems, especially with innovations such as rooftop gardens and vertical forests being established. Anthropogenic technological advancements such as supplementary watering systems, have the potential to offer novel habitats and niches for species quite different from those in more natural ecosystems (McKinney, 2002). 

However, just because urbanisation poses a threat to biodiversity, it does not mean that cities cannot sustain diverse ecology. In fact many cities have high species richness and several are located within 'biodiversity hotspots'. Such cities include, Berlin, Brussels, Chicago, Frankfurt, Helsinki, Mexico City, Sao Paulo, Singapore and Vienna. The assessment of Cities and Biodiversity Outlook (CBO) argues that cities should facilitate for a rich biodiversity and look after the multitude of ecosystem services, such a rich biodiversity can provide, rather than being the culprit of enormous ecological footprints. With such a diverse ecology, cities have the potential to mitigate the effects of climate change. The Japanese district of Yokohama, which emitted almost 20 million tonnes of carbon dioxide in 2007, has now recognised the importance of biodiversity in stabilising the local climate. Innovations such as green roof tops and walls have been developed to act as carbon sinks (SRC, n/d). It is now being acknowledged that it is the responsibility of architects to develop 'green' cities, including creating an integrated holistic approach to create sustainable urban infrastructure. 

To create sustainable cities, developments such as green corridors along highways, railways or bikeways have been planned. There are many new and exciting ways in which architecture and biodiversity are becoming linked. Edwards (2010) explains how the political focus on global warming has tended to reduce the importance of architects in protecting biodiversity. However, the impacts that architecture has upon ecosystems, including decisions regarding building materials, sourcing the materials, rehabilitation of existing structures, decisions regarding walls, roofs and landscape, are enormous. Architects can see this as an opportunity to connect architecture to nature. An example of this is by Edwin Lutyens, who created bat and owl boxes within roofs, making them part of a more ecological architecture (Edwards, 2010). Although architecture does not traditionally concern itself with such matters, the growth of sustainability focused global narratives and EU regulation exposes building design and construction to the close scrutiny of the biodiversity movement. Some architects have already started to fill in the gap. The 'cradle to cradle' idea owes much to an understanding of ecological systems, taking principles from nature and applying them to buildings. It is a holistic framework that aims to create systems that are efficient and also essentially waste free. Similarly the 'biomimicry' design movement and such innovations as bioclimatic skyscrapers and green urbanism promoted over a decade ago, have a clear commitment to addressing biodiversity (UICN, 2013). Ken Yeang, a Malaysian architect and ecologist inverted the high-rise to be designed as a 'city-in-the-sky'. The first example of this was the National Library Singapore (2005). The building features large 40m high 'public realms-in-the sky' in the form of two landscaped sky court gardens.  

Urban design provides the framework for the effective use of land, allowing greenery and biodiversity to penetrate the city. With good design, urban areas can provide opportunities, not merely threats, to ecological diversity. These corridors of biodiversity, including urban wetlands, allotment gardens, botanic gardens, parks and roadside trees can be linked into a network, creating a 'green' city. Architects also have a key role to play to reduce energy consumption. The choice between steel, concrete, masonry or timber construction is complex from an energy point of view (UICN, 2013). However, society is trying to gain a better understanding of green construction. 

Two examples, where the connections between urbanisation and biodiversity are being acknowledged are London Heathrow and Mayesbrook Park. London Heathrow has recently completed a new survey of the biodiversity in its 30 hectare site. They found that the airport offered a range of habitats including grassland, and other landscaped habitats. Within these habitats Heathrow was home to a multitude of rare species of bats, spiders and insects. In total it discovered 129 species of spider and 304 species of beetles (Travel News UK, 2013). This goes to prove that not all urbanized areas threaten species biodiversity, in fact, if the design is incorporated with green infrastructure in mind, species can actually flourish in man made habitats. London's Mayesbrook Park, in urban East London, has transformed a rundown 45 hectare park into a showcase of public green space. The project involved creating a new floodplain that can naturally store floodwater, planting new shrubs and trees to enhance habitats for species encouraging increased biodiversity. This £3.8 million project clearly demonstrates how restoration of biodiversity in cities, can also provide other knock on effects such as climate change adaptation and enhance the well being of people living in the city (Convention of Biological Diversity, 2011). 

Mayesbrook Park,  East London

Overall, cities can provide a unique habitat, one that can produce a rich biodiversity. With an increasing urban population, 'green' urbanism is key to producing sustainable cities in the future. It is vital that governments and planning agencies take into account the benefits that new urban spaces can provide to not only biodiversity but also to localised climate change and air pollution. With urban habitats being surprisingly diverse, such richness of habitats also results in the generation of multiple ecosystem services, which can contribute significantly to human well being. With growing awareness of the value of biodiversity and ecosystem services cities with rich native biodiversity should ensure that their biodiversity is conserved. I will leave you with the words of Professor Thomas Elmqvist, scientific editor of the assessment at SRC, 'cities need to learn how to better protect and enhance biodiversity because there is a direct relationship between biodiversity and many ecosystem services'. 

Score Board Update: Anthropocene 1- 1 Biodiversity