Integrating Biodiversity in Urban Setting

Hortense Serret, PhD - Independant Consultant

Mook Eco +, National Institute of Ecology, Vol. 3.

Biodiversity and Biophilia

The term “Biodiversity” – Diversity of Life – was introduced in 1986 by W.G. Rosen during the planning of the National Forum on Biological Diversity that took place in Washington DC (USA), then popularized by Edward O. Wilson in 1988. Biodiversity is now widely used among the scientific, environmentalist, and political contexts. The term is generally defined as the diversity of genes: the intra-species diversity, diversity of species, inter-species diversity, diversity of the ecosystems, and the interaction between all these elements. According to the IPBES report (IPBES 2019), biodiversity is part of the “Living Nature”, representing “the nonhuman world, including coproduced features, with particular emphasis on living organisms, their diversity, their interactions among themselves and with their abiotic environment.”

For Edward O. Wilson, biodiversity represents more than just exploitable resources for humans. According to him, the diversity of the natural world, while assuring the resilience of the ecosystems (Olivier et al., 2020), is also vital to the well-being of humanity. This is not surprising that the emergence of the concept of biodiversity coincided with the one of “Biophilia” – literally meaning “Love of Life”. While the term was first coined by Walter G. Rosen in the mid-1980s, it was Edward O. Wilson who made it popular after the publication of his book Biophilia: The Human Bond with Other Species. Wilson describes the concept of Biophilia as the “innate tendency to focus on life and lifelike processes, “the “innate emotional affiliation of human beings to other living organisms” or the “inborn affinity human beings have for other forms of life, an affiliation evoked, according to circumstances, by pleasure, or a sense of security, or awe, or even fascination blended with revulsion” (Wilson, 1984).

According to this definition, the emotional link with nature, inherited from our co-evolution within the natural world, is vital for humans’ physical health and well-being. Following this idea, research works initiated to better understand the healing effects of nature. Roger Ulrich (1984) compared the recovery capacity of surgical patients based on whether they had a view on nature from their room. His results suggested that patients who stayed in the rooms with a natural view had shorter postoperative hospital stays and took fewer potent analgesics. Following this work, Rachel and Stephan Kaplan formalized their “attention restoration theory” to show how the contact with nature had restorative effects, not only on our physical capacity but also on our minds by decreasing stress and anxiety (Kaplan, 1995).

Despite our needs for nature, most humans living in urban areas are experiencing nature less and less. Since 2007, the majority of the general population is living in cities and the tendency is far away from decreasing. By 2050, urbanization is supposed to reach 68 % of the global population, according to the UN (2018). In developed countries, it is already reaching 85 % on average. While urbanization is one of the main drivers of biodiversity erosion according to the IPBES report (2019), it also leads to a more general disconnection of city-dwellers with the natural world. The phenomenon has been formalized as the “extinction of the experience” by Robert Pyle in 1978. According to this theory, the lack of direct contact with natural elements is leading to the disaffection of nature. This idea has been taken over by several researchers to show that the extinction of the experience could also lead to behavioral changes towards nature. The less we are emotionally connected with nature, the less we are willing to protect it (Soga et al., 2016).

For Stephan Kellert (2016), the main reason behind our “disconnection” with nature is due to the design and the development of the modern built environment, which eliminates nature and treats it as a design accessory in most cases. While humanity has evolved in a natural world full of stimuli linked to our environment, most humans currently spend 90 % of their time in buildings completely disconnected from nature. The idea of a “Biophilic Design” was developed as a way to recreate stimuli linked to nature or “nature experiences” in the built environment. Kellert established several principles of biophilic design that can be applied for the effective practice of architecture and design in order to integrate:

- Direct experience of nature: including direct contact with environmental features (meaning visual contacts and possibility to touch and feel) such as plants, animals, air, water, natural light, and landscape.

- Indirect experience of nature: contact with representation and images of nature or exposure to particular patterns and processes characteristics of the natural world. This includes pictures and artwork of nature, and the integration of natural materials and design inspired by natural shapes or elements and architectural features or design using biomimicry.

- Experience of space and place: possibility to experience architectural features including characteristics of the natural environment that have advanced human health and well-being such as place reminding “security” (“Prospect and refuge,” “Mobility and wayfinding”) or the complexity of nature (“Natural complexity”).

Reintegrating nature at the scale of the building and in urban areas, in general, is a way to bring city-dwellers closer to natural elements. As mentioned by Miller (2005), the reintegration of nature in the built environment has tremendous potential to support biodiversity but also to contribute to people’s physical and emotional health and well-being. Urban strategies emphasizing quality-of-life enhancement might also be more effective from a conservation point of view than politics calling for altruism, ethics, or self-sacrifice regarding environmental issues. Following this idea, the optimization of green spaces in urban areas is a way to conciliate all these issues.

Significance of Green Spaces in Urban Areas

From reconnection to nature to biodiversity conservation and in urban areas

The reintegration of biodiversity, not only at the building scale but also at the city and regional scale, is a way to recreate opportunities of reconnection with nature. Numerous recent studies showed that beyond the psychological benefits (van den Berg et al., 2016), accessibility and regular access to urban green spaces where people live also brought benefits to general physical health (Richardson et al., 2013; Tzoulas et al., 2007). Where people work, access to green spaces during working days has also shown to have positive impacts on decreasing employees’ stress, absenteeism, and even have a strategical interest. Indeed, some authors proved that access to and view of nature could also improve employees’ productivity (Lottrup 2011).

The development of green spaces in urban areas appears to be the best way to recreate suitable habitats for biodiversity. In San Francisco, urban parks providing diversified food resources could be considered as a refuge for bumblebees as the city scales (McFrederic, 2006). In the UK, Baldock and al. (2019) showed that within four major cities, residential gardens, and allotments (community gardens) were considered as pollinator ‘hotspots’. In these cities, the proportion of these types of green spaces are representing extensive areas. Infrastructures such as green roofs and walls are also a way to recreate suitable habitats for biodiversity and to contribute to ecological connectivity as “stepping stones.”

The interests of urban green spaces from a conservation point of view are linked to the connectivity, i.e., the capacity of dispersion of species into the urban matrix. Maintaining these displacements capacities is crucial in order to maintain genes flow and, hence the resilience of the populations. If the network of urban green spaces is helping maintain the connectivity in dense urban areas, other green spaces such as green spaces at business sites can also be mobilized to enhance connectivity in suburban areas (Snep et al., 2006; Serret et al., 2014).

Other ecosystem services provided by urban green spaces

More generally, green spaces in urban areas also provide several ecosystem services that can be crucial for the capacity of resilience cities can have. In the framework of the development of urban agriculture, the presence of pollinators is ensuring crop production, as it is the case in San Francisco (Potter and Lebuhn, 2015). Other services such as flood control (Liu et al., 2014) and reduction of urban heat island effect (Oliveira et al., 2011) are directly correlated with the size and areas occupied by green spaces. This last aspect is crucial in a context where climate change is threatening the health of the most vulnerable people, especially in urban areas. Son et al. (2016) showed that in a city like Seoul, the areas with less vegetation were associated with a higher rate of mortality due to high temperatures.

Nature-based solutions inside cities are vital for city-dwellers’ well-being and health and adaptation to climate change. In 2004, the Cheonggyecheon Restoration Project, the most expensive river restoration in the world thus far, took place in Seoul and resulted in the removal of an urban highway. The original stream was re-opened, and a 6 km-long continuum of green spaces along the stream was created. This project illustrates the city’s effort to create more eco-friendly and people-oriented urban spaces. The green spaces created by this project are conciliating city-dwellers’ well-being and biodiversity conservation by locally improving air quality, reducing the heat urban island effect locally (Lee and Anderson, 2013), and creating suitable habitats for numerous groups of species (Kang et al., 2012).

Suggestions to Improve Green Spaces in City

To insure their interests for biodiversity conservation and the capacity to reconnect city-dwellers with nature, the design of urban green spaces must satisfy specific characteristics such as the size, connectivity, and capacity to create multifunctionality by conciliating engagement and the presence of suitable habitats for biodiversity. The design and integration of native plants and trees, the diversification of habitats and vegetal strata, and the general management have been, and the communication around it are the most effective measures to increase urban green spaces quality for biodiversity and people.

Making space for nature and connecting the dots

Making more space for nature inside cities is the main objective and the enhancement of connectivity at the urban scale can be done thanks to the development of a sustainable urban planning thanks to:

(1) the identification of biodiversity hotspots or “reservoir” at the local scale. The interests of these spaces are linked to the diversity and rarity of natural habitats (such as wetlands, ponds, natural meadows) and the presence and diversity of species linked to them. A hierarchy of the most interesting ones can be a way to prioritize the protection of these spaces from urbanization and to restore the capacity to attract biodiversity for the other ones.

(2) the identification of corridors connecting the reservoirs between them in order to allow species movements and dispersion. The conservation of the most important corridors and restoration of new potential ones is a way to conciliate ecological issues and the creation of multifunctional spaces dedicated to soft traffic, walking paths, and even environmental education.

As finding available areas in dense urban areas is often an issue, revegetation can be done on buildings on their rooftops and walls (Mayran and Clergeau, 2018) but also at the bottom of urban trees or by installing plants boxes in the streets. 

Generalizing ecological conception and management of green spaces

Conception and management of green spaces appear to be the most important factors influencing habitat quality for biodiversity. From the conception to the general management, several guidelines are critical to addressing species needs regarding food access, reproduction, and resting zones:

 - Privilege native species. Native species are more adapted to local biodiversity because they provide more adapted sources of food and nutrients. They also require less management (as watering) and are more resistant to environmental conditions.

 - Diversify habitats. At the design stage, the diversification of habitats and strata is key to create different refuges for wildlife such as pounds, wetlands, bushes, or meadows. These habitats can be designed to have several functions. For instance, wetlands can be designed to manage rain waters.

 - Slow down mowing frequencies. It has shown that reducing mowing frequencies was influencing the diversification of the flora and was a good way to support pollinators in urban areas. Indeed, it allows the flowering of plants producing pollen and to create refuge areas.

 - Ban the use of pesticides. The use of pesticides in domestic gardens has shown to have negative impacts on bumblebees and butterflies. Weeding can be done thanks to alternative methods such as thermic or steam.

 - Take care of the soil. Mulching is a technique that never leaves the soil naked. Adding straw or green wastes between planting is a way to prevent soil from drying (and therefore requires less watering), providing nutrients it requires.

 - Install shelters for wildlife. If localized adequately, nest boxes for birds and bats such as insect hotels can enhance reproduction capacities of several groups of species

The importance of communication

Communication to make people understand why and how the ecological management of green spaces is important for biodiversity conservation. Raising people’s awareness about biodiversity issues by providing them educational content or activities such as citizen sciences is also a way to make people understand why human well-being is so deeply linked to nature and how dependent we are from it. 

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