The role of cities in preserving biodiversity

Writer: Marcus Ng

Natural habitats and their biodiversity are increasingly seen as vital components of liveable cities. They provide spaces for recreation and help to restore physical and mental health. Urban parks and forests also contribute to a sense of belonging and well-being. We look at what cities can do to protect them.

Cities mentioned in this article:
Austin, Singapore, Vienna, Melbourne, Bangalore, San Francisco, Havana, Bogotá, Curitiba

Melbourne aims to be a city in a forest with an ambitious urban forestry strategy

We are not alone on this planet. It may seem unbelievable, but humanity shares the Earth with a spectacular biological diversity or biodiversity of more than 1.2 million ↗ (opens in new tab) known species of plants, animals and other living organisms. Cities, far from being barren concrete jungles, are emerging as havens for many species of plants and animals, which have learnt to survive in built-up environments or thrive in urban parks, gardens and other green lungs. Falcons and coyotes hunt between New York City’s skyscrapers, pumas lurk in the wooded valleys of San Francisco, while otters and hornbills occupy the parks of the island-city of Singapore.

At the same time, we now live in a largely, and increasingly, urban world; by 2050, nearly two-thirds of the world’s population will reside in urban zones ↗ (opens in new tab). But as cities expand, they run the risk of losing habitats rich in biodiversity as well as the ecosystem services provided by these natural environments. Such ecosystem services ↗ (opens in new tab), which are often taken for granted and extremely costly to replace when lost, include the provision of freshwater catchment areas; protection from floods, storms and erosion; carbon capture and storage; and climate and pollution control.

“Cities, far from being barren concrete jungles, are emerging as havens for many species of plants and animals, which have learnt to survive in built-up environments or thrive in urban parks, gardens and other green lungs.” — Writer

The value of biodiversity

The ecosystem services provided by biodiversity affect us in very direct ways. Forests and wetlands supply the oxygen we breathe and absorb the carbon dioxide that would other contribute to climate change. Bees, birds and butterflies perform essential pollination services for many crops; when their habitats are destroyed, the ecosystem services provided by these creatures are also threatened and may be very costly, if not impossible, to replace.

In addition, natural habitats and their biodiversity are increasingly seen as vital components of liveable cities. They provide spaces for recreation and help to restore physical and mental health. Urban parks and forests also contribute to a sense of belonging and well-being, by offering what Timothy Beatley, Teresa Heinz Professor of Sustainable Communities at the University of Virginia, USA, calls “opportunities to experience awe and wonder”. In Japan, for instance, city folk have embraced the practice of shinrin-yoku or ‘forest-bathing’, by regularly walking through lush forests in order to lower their stress levels and recharge their spirits.

Steffen Lehmann, Professor and Head of the School of Architecture at the School of Built Environment at Australia’s Curtin University, also sees a strong link between investing in nature and greater liveability. “Urban greenery” he states, “has benefits such as increased wellness, growing bird populations and providing the ageing population with new meeting places.”

Preserving biodiversity also makes good economic and business sense. Professor Beatley offers the example of Austin, capital of Texas in USA, where the city’s main bridge inadvertently became a roost for some 1.5 million bats after it was built in 1980. People were initially worried about health and thought of eradicating the colony. But after working with an environmental group called Bat Conservation International, Austin has become 'bats' over the animals. “Not only did they not eradicate the bats, they are celebrating them,” explains Professor Beatley, who points out that the bats now generate millions of tourism dollars as people from all over the country flock to the bridge every evening to see the spectacular flight of the bats, which also perform the added service of consuming agricultural pests. “There are even bat-watching cruises on the river,” he adds.

Bat-watching in Austin, Texas, USA

The challenge of preserving green spaces and their associated ecosystem services is compounded in many cities in developing regions, however. According to Professor Lehmann, who served as UNESCO’s Chair for Sustainable Urban Development for Asia and the Pacific from 2008-2010, “The track record for the preservation of substantial tracts of greenery and natural habitats in these cities has mostly been very poor or appalling.” One reason for this is that these cities are already struggling with long-term planning in general and the provision of basic needs such as infrastructure, transport and housing.

There are, however, real, even tragic, costs of not factoring greenery into city plans. “Developing cities are losing green spaces at a dangerous rate or lack good green spaces in their urban planning proposals,” comments Professor Lehmann. “This has detrimental effects, such as a change of their urban microclimate and increase of risk of the dangerous urban heat island effect.”

Professor Lehmann cites the recent example of a heatwave that killed more than a thousand people in Pakistan in June, due to immense heat that was trapped by concrete roofs and asphalt but was not dissipated at night. “If there are no cooling parks or gardens, survival in these affected cities becomes critical and the mortality rate can double during heatwaves,” he explains. “Here, we find that investment in urban greenery delivers immediate and quantifiable benefits and does not need any long-term payback periods: just the amount of energy saved that otherwise would be needed for cooling is significant for a large city.”

Professor Beatley, who founded the Biophilic Cities Network of cities seeking to incorporate nature as an essential element of their urban design, is in agreement with this, stating his view that biophilic cities “are more resilient in the face of climate change and other challenges.”

“Urban greenery has benefits such as increased wellness, growing bird populations and providing the ageing population with new meeting places.” — Professor Steffen Lehmann (Professor and Head of the School of Architecture, Curtin University)

Measuring urban biodiversity

A crucial step to protecting urban biodiversity is knowing how much of it exists and which habitats are of high value for their biodiversity and ecosystem services. This process requires a different methodology from that used in country-wide studies; hence, a dedicated tool called the City Biodiversity Index (CBI) has been developed by Singapore’s National Parks Board with the co-operation of the United Nations, and was launched in 2010 at the 9th Meeting of the Conference of Parties to the Convention on Biological Diversity at Nagoya, Japan.

Dr Lena Chan of the National Parks Board, who helped develop the CBI, explains that the Index serves “as a long-term monitoring tool for city governments to evaluate their biodiversity conservation efforts”. Since its launch, the CBI has been applied by 24 city governments worldwide. “Academics have applied the index to a further 14 cities,” Dr Chan reveals. “In addition, twelve more city governments are currently in the process of applying the index.”

The CBI offers cities a self-assessment tool to measure their biodiversity and determine where protection is most needed. “The scores can help the cities decide on how to prioritise their resources,” explains Dr Chan. “For example, the city council may allocate more financial and manpower resources to indicators that have low scores so that they can improve on the areas of weakness. The parameters measured by the CBI include: the proportion of natural areas in a city; the proportion of protected natural areas; an assessment of the ecosystem, recreational and educational services of natural areas; institutional capacity; and public participation and partnerships. Sharing his view on the index, Professor Lehmann said, “Singapore has developed a world-class methodology with the Cities Biodiversity Index.”

Creating green cities and corridors

A growing number of cities worldwide have made natural habitats an integral part of their planning and development. One city that stands out in its proportion of green spaces is Austria’s capital, Vienna, where meadows, gardens, parks and woods make up nearly 50 percent of the metropolitan area ↗ (opens in new tab). This green cityscape arose from a deliberate zoning plan that protects designated green areas and valuable ecosystems. In addition, the city authorities periodically acquires land that is set aside as parks, which number some 2,000 across a city of 200 square kilometres. Households are also encouraged to grow trees in their courtyards and plant rooftop vegetation, and the city works with environmental groups to nurture suitable wildlife habitats such as butterfly meadows, bird-nesting areas and urban wetlands.

Elsewhere, Professor Lehmann offers the example of Australia’s “202020 Vision” ↗ (opens in new tab), which was launched in 2012. “The ‘202020 Vision’ explores how business, government, education and community in Australia can work together to increase green space and create 20% more green space in our urban areas by 2020,” he explained. “It has been a very successful initiative to incorporate urban greenery in every new masterplan and project. We have seen a real shift in attitudes towards street trees, the creation of urban forests and community gardens.”

Melbourne, which is part of the 202020 Vision network, has been making huge strides in urban greenery. In recent years, the capital of Victoria state has embarked on an ambitious urban forestry strategy with the goal of doubling its forest canopy coverage by 2040. “They don’t just want to plant trees,” remarks Professor Beatley, “They want to be a city in a forest”. What is more, the city has initiated “very creative ideas to get the public engaged and interested”, namely by giving every tree in Melbourne its own identification number and email address. “You are encouraged to send your favourite tree an email, and the trees will answer your email!”

Such efforts recognise that public engagement and involvement are vital to get people invested in preserving and caring for the nature around them. Professor Beatley offers another example in the Indian city of Bangalore, where residents have been taking part in an Urban Slender Loris Project to monitor small nocturnal primates that dwell in the city’s trees. For him, this is a prime example of citizen science that “gets citizens personally engaged and curious about what is in their city, and enlists their support to learn more about the biology of this species.” Meanwhile, in San Francisco, USA, a programme called the Bay Area Puma Project is educating schoolchildren about coexistence with the pumas or mountain lions in the area. “For me, the agenda is also about sharing space, about reimagining cities as places we share with other form of life,” states Professor Beatley. “Can you imagine living in a city where you might have a glimpse of a mountain lion? I want to live in a city where that is possible.”

“Can you imagine living in a city where you might have a glimpse of a mountain lion? I want to live in a city where that is possible.” — Professor Timothy Beatley (Teresa Heinz Professor of Sustainable Communities, University of Virginia)

Healthier habitats for humanity

Looking ahead, Professor Lehmann expressed his view that strategies for urban greenery must “also include developing and emerging cities.” These cities with a population of 500,000 to a million, he remarked, often grow much faster than established megacities and require a forward-looking planning strategy that “includes green corridors, green belts or community gardens with increased shade” in order to improve the quality of life for as many residents as possible.

Professor Lehmann cited Havana in Cuba, Bogotá in Colombia and Curitiba in Brazil as developing cities that have successfully invested in urban greenery and thereby raised their liveability. “The time has come to learn from these positive cases of cities that have managed to achieve progress outside of Europe and North America, and replicate the formula through a buy-in of communities, developers and planners,” he stated.

Curitiba, for instance, has made decades-long efforts in habitat and environmental protection that have made it Brazil’s so-called “Green Capital.” The capital of Paraná state, Curitiba had less than one square metre of greenery per inhabitant in 1970. But thanks in part to legislation that preserved its biodiverse local forests, this city of 3.2 million now offers every resident approximately 52 square metres of greenery and ranks as one of the world’s largest urban green areas. Curitiba has also blended environmental protection and social development in a Green Exchange programme whereby low income families in shantytowns can exchange their domestic waste and reusable items for bus tickets, food and school items, an initiative that has led to a recycling rate of 70 percent ↗ (opens in new tab).

Ultimately, cities rich in urban ecosystems provide healthier habitats for humanity as well. Professor Beatley believes that this not an option. “I believe it is something we absolutely need to lead healthy, happy and meaningful lives in the urban environment,” he states. “We need to promote dense, compact cities, but also to incorporate nature into them.”

On his part, Professor Lehmann calls for the inclusion of green spaces as part of good urban design practice, be it “by retaining and preserving, or by creating new gardens and greenery.” And in an era when cities will confront the effects of climate change and higher average temperatures, planners must combine private and public investment “to facilitate cooler cities, which are cities that stay cooler, even in future heatwaves.” Besides providing spaces for both nature and people, “a cooler city” concludes Professor Lehmann, “is a more sustainable and healthy city.”