Background: the value of urban rewilding
The problem: loss of urban greenery and biodiversity
Globally, urban sprawl is responsible for the loss of greenspace around the city periphery, while densification threatens inner-city greenspaces (Haaland and Konijnendijk van den Bosch 2015). This loss of greenspace makes cities less hospitable to wildlife, which is suffering alarming decline. The UN’s Global Assessment Report on Biodiversity and Ecosystem Services concludes that global biodiversity levels on land have dropped by at least 20% from 1900 and around one million species are at risk of extinction, with changes in land use being the main driver (Díaz et al. 2019). Given this pressure on all land, urban wildlife habitat will become increasingly important to mitigate biodiversity decline.
Wider implications: the value of nature for cities and people
Urban nature benefits cities and their human inhabitants, as well as wildlife, boosting health, wellbeing and the economy.
Residents of urban areas with a higher proportion of green space report better general health (Maas et al. 2006). The benefits of urban greenery stem from the fact that being in a natural environment lowers our blood pressure, pulse rate and stress levels (Park et al. 2010), and makes us feel cognitively and emotionally restored (White et al. 2013). Moreover, the contribution urban green spaces make to our psychological wellbeing has been shown to increase with their biodiversity (Fuller et al. 2007).
In addition, nature has a monetary value, contributing an estimated $125 trillion a year to the world economy through ecosystem services (Costanza et al. 2014). These include providing beneficial processes, such as air purification, temperature regulation and flood protection in cities, and the presence of biodiversity has been shown to be important for their effectiveness (Harrison et al. 2014).
As we deprive our urban areas of greenery and wildlife, they therefore function less well and become worse for people. With nearly 70% of the world’s population expected to live in cities by 2050 (UN 2018), the vast majority of us would benefit from them having a greater prevalence of nature.
The solution: rewilding our cities
We can help reverse these trends of green space and biodiversity loss, by adapting our cities to attract more wildlife, making them healthier and more sustainable places in the process. To this end, principles from the rewilding movement that is restoring lost ecosystems in rural landscapes—of creating spaces for wildlife to re-colonise and enabling people to reconnect with the natural world—could be applied to cities. Indeed, in cities, dense populations could better facilitate engaging communities in this process.
Restoring greenery would be particularly beneficial in cities, contributing to a functioning ‘urban ecosystem’. Firstly, it can mitigate the poor air quality, caused by their high concentrations of traffic and wood-fired appliances, by blocking and dispersing pollutants (Janhall 2015). Secondly, it can address the issues of urban overheating and surface flooding, caused by the ubiquity of hard, dark surfaces in built-up areas, through shading, evapotranspiration and promoting infiltration (Gill et al. 2007; Pauleit and Duhme 2000). These benefits will be increasingly valued as climate change is expected to cause greater incidence of extreme heat and heavy rainfall in many regions (IPCC 2018).
In parallel, cities can make a difference to biodiversity loss. In Britain, built-up areas host twenty percent of the blackbird, starling and song thrush populations and significant numbers of other species (Gregory and Baillie 1998). Species such as peregrine falcons are choosing to become urban specialists, attracted by the nesting-site potential of tall buildings and ready food supply of feral pigeons (Kettel et al. 2019). Further, targeted conservation efforts have prompted increases in urban populations of some bat species (Hayhow et al. 2016).
The target: residential streets
Loss of greenery from residential areas of cities presents a specific problem, when domestic gardens cover a quarter of major UK cities and contribute a significant proportion of urban vegetation (Loram et al. 2007). Urban gardens, regardless of their small size and remoteness form the countryside, support a huge diversity of wildlife (Smith et al. 2006, 2010; Thompson et al. 2004). In the UK, some species, including the hedgehog, song thrush and common frog, are now more successful in urban gardens than the rural farmland that was once their stronghold (Gregory 1998; Mason 2000).
Aims: engaging residents through drawings
Hypothesis: vision drawings
Visualisation techniques, including freehand sketching and photorealistic computer imaging, have been found to be effective at engaging city residents in planning processes (Al-Kodmany 1999). With this knowledge, the study was developed to explore the hypothesis that architectural drawings combining these representation methods could inspire residents to take an active role in rewilding cities. This was formulated in the research question ‘Could architectural drawings be useful in persuading residents to rewild their streets?’.
The primary research question generates a series of sub questions, in terms of drawing content, presentation techniques and dissemination:
What drawing methods would be engaging for residents?
What positive aspects of urban rewilding should the drawings highlight to residents?
What barriers to urban rewilding should the drawings seek to dispel among residents?
How could the drawings relate to practical guidance to form a useful resource?
How would the drawings reach a public audience?
Architectural drawings have the potential to communicate a vision of a city adapted to enhance its greenspace and biodiversity. Such representation of a biodiverse city could be used to educate and influence inhabitants, designers and policy makers to develop and maintain the city in a way that works towards this vision.
Focusing the vision on existing residential streets would address the significant issue of loss of wildlife habitat in urban gardens. Drawings could inspire and empower residents to make changes to their neighbourhood by showing aspirational ideas, making a cohesive proposal at a whole-street scale, and organising diverse information and guidance.
Appealing images showing how a typical urban residential street could look, after sensitively integrated adaptations, could inspire people to make changes by enabling them to imagine the positive effect on the appearance and experience of their neighbourhood.
Drawings at the scale of a residential street would show a cohesive proposal, highlighting the potential connectivity of private gardens and critical mass of habitat they can offer when viewed together as a street, if every resident makes even small changes.
Different drawing projections could be used to organise diverse, expert guidance to inform people about potential urban wildlife species and habitats, and empower them to implement biodiversity measures through products or activities.
Literature summary: representation in ecology guidance
A review was undertaken of the use of drawings and other imagery in UK ecology guidance for residents to determine whether architectural drawings could add anything useful to the field.
The Royal Society for the Protection of Birds (RSPB) and Barratt Homes are collaborating to integrate biodiversity in a new-build housing development on a greenfield site. A combination of annotated drawings and photographs is used to communicate the wildlife features, which include orchards, hedgehog highways, and habitat boxes, to prospective residents (Thomas 2018). The projections used, a site plan and three-dimensional aerial view, are considered successful at showing the proposals at neighbourhood scale, giving the sense of a verdant place with gardens connected to each other and the wider landscape. The aerial view in particular would seem easy for lay people to interpret, and makes good use of people and animals to suggest animation and occupation of the outdoor spaces. However, the illustration style arguably has a simplistic, cartoonish quality: this neither conveys a strong aesthetic design sensibility behind the integration of biodiversity measures nor gives a sense of realism to help people imagine how the development would feel.
Numerous conservation bodies offer advice on wildlife gardening, species and habitats online. The most relevant are RSPB’s ‘Give Nature a Home’, and Royal Horticultural Society (RHS) and the Wildlife Trusts’ ‘Wild About Gardens’ campaigns. These mostly use infographics and photographs in an appealing way. Where used, drawings take the form of scientific illustrations isolated from any context, although the use of hand drawing lends a certain charm. This approach puts the emphasis on adaptations at an individual garden scale, without considering integration with the garden layout or adjoining buildings, or conveying the transformative effect that could be had across streets as a whole. The wealth of expert advice from different organisations can also be hard to navigate, particularly to find information specific to urban species or habitats. Where products to encourage wildlife are recommended, this is done without apparent consideration of their aesthetic merits or compatibility with an urban setting. There is no known design-based advice for the public on sensitively integrating wildlife provision within existing urban streets. There is therefore scope to create guidance that is more persuasive and targeted at city residents by demonstrating considered aesthetic integration of biodiversity measures, showing cumulative impacts at street scale and highlighting an urban application. Drawings were judged to be an effective medium to achieve this, as they enable the designer to invent and control what is shown. Drawing projections and methods were needed that would combine the positive aspects identified above, such as hand drawing and infographics, but give an impression of realism and underlying design thinking. To this end drawing precedents used in design fields were explored.
Books on place-making by Christopher Alexander and on sustainable design by Huw Heywood were consulted for their engaging use of architectural drawings and diagrams to show model designs (Alexander et al. 1977; Heywood 2015). Although intended primarily for a more professional audience, their use of simple, hand-drawn sketches, a variety of drawing projections to capture different ideas and concise annotation to show design principles would be transferable to a lay one. Heywood’s use of colour seems especially important to engage a broader demographic. Sarah Wigglesworth Architects’ sustainability diagrams for Sandal Magna Primary School in Wakefield were admired for presenting sustainable design concepts in an accessible manner. These concern proposals for primary schools and would therefore be used during the consultation process to engage planners, user and community groups, and the public in proposals. One would assume the use of simple annotated diagrams, hand-drawing, three-dimensional aerial views, colour and leader lines to explain features in more detail contributed to the success of the drawings in convincing these consultees, resulting in the project being built. Finally, the work of certain landscape architects, such as J & L Gibbons and The Edible Bus Stop, makes good use of image-editing software to show photo-realistic vegetation in proposal drawings used for public consultation. These often show proposals at neighbourhood scale, combining perspectives with more traditional plan and section views. The review determined that a combination of these techniques could be applied to successfully represent urban rewilding in an engaging way.
Why study necessary: creating a drawings-based model
The study was necessary to find out whether architectural drawings could form the basis of a resource to persuade city residents to make changes to their homes to benefit wildlife. Such a resource could better engage city residents and address the gaps identified above in existing urban ecology guidance in the UK, inspiring more urban residents to change their gardens to accommodate greater biodiversity.
Finding a means to engage residents is important, as planning regulations in the UK have negligible scope to control the management of private gardens (Gaston et al. 2005). Policy includes only basic restrictions on impermeable surfacing in front gardens (Communities and Local Government, Environment Agency 2008), unacceptable development in back gardens (Smith 2010) and protected tree removal (Communities and Local Government 2012). Empowered residents might also campaign for their local council to make changes to their streets, and for government and the city mayor to strengthen policy with respect to the existing residential built environment.
The researchers identified an opportunity to reveal original insights through drawings. These comprised creating visually oriented guidance to appeal to lay people appreciating good design; showing a holistic, design-led approach integrating architecture, landscape and urban design; illustrating rural rewilding principles applied to an urban context to allow cities to benefit from species richness; featuring existing, residential streets depicted at a street scale to capitalise on the biodiversity potential of domestic gardens; and collating and organising disparate existing guidance relevant to urban situations.
If effective, this resource would provide a practical, scalable model for effecting change in London and other conurbations. This would help address the wider issue of increasing urbanisation contributing to biodiversity loss worldwide and underpin a future global network of biodiverse National Park cities to counter this trend.