The Biodiverse City

Joel Gilbert and Bob Gilbert

During those long, hot days of the first lock-down we spent a lot more time in our garden, in the heart of London’s East End, watching birds come to the feeder and hoverflies dart about the flowers. The country seemed united then, and nature more confiding. If you sat quietly for a while, the female blackbird that had been prospecting for a nest site, would come and feed almost at your feet, and the little wood mouse dart out from a patch of weeds to nibble the crumbs that had fallen by the chair. 

Of the several recorded responses to lock-down, the feeling of being ‘closer to nature’, and of wanting to ‘experience the outdoors’, became one of the recurring themes. Through its agency, Natural England, the government made some attempt to quantify it. Their ‘People and Nature Survey for England’ showed that between April and August 2020, the number of people spending time outdoors had increased by 43% over the previous year, with 37% of adults also saying they wanted to spend ‘more time with nature’. More striking still were the responses from children, 83% of whom agreed that ‘being in nature made them happy’. It was a theme repeated in numerous newspapers and magazine articles and on radio and TV. It even seemed to be fuelling a ‘flight from the city’, with estate agents reporting a significant increase in the number of people trying to move out of London. Perhaps it was also confirmation of the report from the University of San Francisco which had made headlines in September, with its claim that a weekly 15-minute walk with ‘moments of awe’ could boost pro-social emotions and mental wellbeing.

It is surprising then that all this was happening at the same time that massive environmental degradation and biodiversity loss were accelerating. Or perhaps it isn’t. Susan Sontag once argued that wildlife photography only really took off when wildlife itself was declining, or, as Joni Mitchell put it more succinctly, ‘you don’t know what you got till it’s gone’. And the figures for that wildlife loss are staggering. The latest World Wildlife Fund ‘Living Planet Report’ suggested a 68% drop in vertebrate populations since 1970, while a report from scientists at Kew, which followed it just a few weeks later, reported that two-fifths of all plant and fungi species on the planet are now in danger of extinction. This loss is not just about elephants and orchids, the distant and the exotic, it is also happening among us and around us. Some of our most familiar birds are in steep decline; swifts, starlings and house sparrows among them, with urban butterflies reducing at a rate that outstrips even that of their rural neighbours. Even the common garden web-spinning spider is disappearing, with a recent European study suggesting that webs had reduced to less than 1% of their former density. Overall, they are figures justifying the claim that we have already entered the sixth great extinction or, as some people prefer to call it, the first great extermination.

How then can we marry these two seemingly paradoxical positions: an increased affinity to and awareness of the natural world, with ongoing devastating environmental decline? Current policy responses to the biodiversity crisis seem to be characterised by an approach to nature as something ‘out there’; the setting aside of specific and separate places where nature can ‘thrive’ or the creation, to use that most worn out of clichés, of ‘wildlife havens’. Traditionally this was based on the formation of nature ‘reserves’, a telling word, and of other specially designated areas. Most recently it has been characterised by the enthusiasm for ‘rewilding’ with books on the subject becoming best sellers and rewilding initiatives, both large and small, springing up all over the country. A ‘Global Charter for Rewilding the Earth’, signed by 96 ‘organisations’ calls for rewilding to be prioritised as a solution to the current climate and biodiversity emergencies, and the UK Government has recently signed a “Leaders’ Pledge for Nature” giving a headline figure of 30% for the amount of land to be protected in order ‘to support the recovery of nature’. Less publicised is the fact that 24% of this figure is made up of existing designated landscapes and SSIs, the majority of which are in declining condition.

There is, nonetheless, a significance to the 30% figure. It is the globally accepted amount if humanity is to live within its ecological boundaries; replenishing fish stocks, sequestering carbon, restoring the natural filtering of polluted water and providing a barrier to zoonotic diseases, such as our current – and future – pandemics. But there is, too, a danger to this ‘out there’ approach, for it essentially characterises ‘nature’ as something separate from humanity; setting aside some parts of the planet for ‘nature’, and the rest, by implication, for ‘people’, as if the two existed in separate biospheres. It is an approach that masks a new form of neo-colonialism, as countries and companies buy up land to offset emissions, without consideration of, or consultation with, the communities that already live there. And it is also an issue of class.  ‘Out-there’ nature is something particularly accessible to the moneyed and the motorised. As Roderick Leslie wrote in the ‘British Wildlife’ journal when discussing National Parks, ‘the idea that they are the green lungs of the nation always leaves me wondering how those of us who live in cities are meant to hold our breaths until the holidays’. It is perhaps illustrative that for his father’s birthday, Boris Johnson paid for beavers to be released on part of his rewilded estate on Dartmoor. Meanwhile, in the public commons, ancient woodlands and wetlands are ear-marked for development through huge infrastructure projects, such as airport expansion, HS2 and the £27 billion road-building programme.

The thought of one day seeing European wild bison in the woodlands of Blean, beavers on the River Otter or lynx in the Scottish Highlands, is both enticing and exciting, but the idea of rewilding, and the wider ‘out there’ approach, can only, at best, be partial. Essentially it must be accompanied by a new understanding, an idea of nature as also ‘in here’, with biodiversity desirable and achievable wherever we live, work and grow our food. And this is where our cities take on a special significance. Our urban areas occupy an increasing land mass and an  ever larger hinterland. They are where, according to the United Nations, 55% of the world’s population now lives, a figure which is expected to rise to 68% by 2050, and which has already reached 83% in England. If we are to rebuild our connection with nature, it is within our cities that we need to begin.

With imaginative thinking and appropriate design, our cities could become not so much the cause of the problem as part of its solution; no longer places where we strive for a clinical sterility but ones where we promote the co-existence of multiple species to our mutual benefit, with spaces that provide both for ‘nature’ and for the essential services of a functioning, resilient city. In an urban context, the idea of nature ‘in here’ can be approached in two distinct ways. The first, as coined by Janis Birkeland, is ‘positive development’, the notion that urban environments can be retrofitted or redeveloped in ways that benefit the wider natural world. Even high-rise blocks, for example, can be exploited to provide a net gain for nature, utilising all their vertical and horizontal surfaces to generate eco-services, including food production and recreational space.   A prime example is the Bosco Verticale in Milan, where two residential towers support nearly 800 trees and 5,000 shrubs planted on balconies. They provide the equivalent of 20,000 square metres of forest and undergrowth, over an actual flat surface area of 1,500 square metres.  Not all approaches need to be this ambitious. The interventions for increasing urban biodiversity are many, and many of them already well tested. They can be as low-tech as leaving areas of park lawn uncut or replacing fences with hedgerows. At a more complex level, they can include fitting out buildings with green walls and rooves, installing permeable paving and swales, replacing hard edges and tarmacked areas with planting, designing houses and offices that encourage nesting birds, creating green corridors and connected open spaces, and even restoring or ‘daylighting’ lost rivers.

The second approach to nature ‘in here’ lies not so much in development as in the absence of it. The idea of leaving space ‘empty’ is anathema to city planners and developers. Too often it seems that wildlife and nature is a gift which can bestowed upon the local, or incoming, human population in manageable, bite-sized chunks, whether in the form of aesthetically-pleasing ‘lollipop’ trees or, for the more progressive developer, a ‘wildflower’ meadow and a bird-box. Whilst there is an increasing number of projects which recognise the importance of nature-based solutions, little attention is given to the places where they already exist. These ‘wild’ places are often the unkempt and naturally unruly parts of a city, a valuable habitat in themselves and home to a specialised flora and fauna which can often contain national rarities. Among our scarcest insect species, for example, 15% are to be found on brownfield sites. Brown can therefore be beautiful, whether it is the ‘peri-urban’ habitats on urban fringes or the small pockets we pass by daily but fail to notice; the unused railway sidings, untended front gardens, or overgrown cemetery. These places support not just biodiversity but important urban eco-services, filtering water, reducing flood risk, mitigating heat stress, and removing air-borne pollutants. Perhaps most importantly, these ‘forgotten’ spaces deepen our connection to the natural world and the wild. Well designed and managed biodiverse cities will incorporate a range of ingenious, and sometimes deceptively simple, development strategies, but they will also recognise the value of a mosaic of ‘untamed’ space in order to benefit both the natural world and humanity.

Together these two approaches involve the blurring of many traditional boundaries. Green space and grey space will need to run into each other, parks and housing estates to embrace, the managed and the wild to collide. Many good examples already exist. The Surrey Quays development in the south London docklands incorporated a strip of woodland running right through it while the city of Sheffield is in the process of implementing one of Europe’s largest sustainable drainage systems, planting it with a range of wildflowers, grasses and shrubs.  Milan aims to plant three million trees by 2030 and to increase its canopy cover from 7% to nearly 20%, reducing pollution and temperatures in the city by up to 2°C. In Malmo’s Bo01 district, set in the old Western Harbour, housing blocks have been set around nature-filled courtyards. The main challenge is to bring these ideas and techniques together in an overall rethink of our cities; and to make them ubiquitous rather than exceptional.

When he was designing the high, brutalist blocks of the Trellick and Balfron Towers, Erno Goldfinger claimed that ‘the whole object of building high is to free the ground for children and grown-ups to enjoy Mother Earth and not to cover every inch with bricks and mortar’. Of course, it didn’t happen like that and the spaces between the blocks became bleak municipal deserts. But why shouldn’t the high-rise block be set in its own nature site, perhaps with a restored brook running through it, the residents providing its wardens, the children its Nature Club? What we are seeking is an approach more rooted in community and based not just on a planner’s vision but an understanding of what’s already there; the ‘weeds’ that grow on the wasteland, the mosses that flourish on top of a wall, the wildlife of the local canal or rail-side, the birds that regularly visit the area. You can no more design an ecology than you can create a community and any attempt to increase biodiversity should begin with a respect for the existing habitat, quirky and imperfect though it might be.  

The idea of beginning with what already exists underlies the significance of mapping in the transformation of our urban areas. We need to observe what is already ‘in here’, what contributes most to local biodiversity and eschew the idea that we already know best for nature. Such mapping could form not only the basis of future planning but for community engagement in the process. Many people during lock-down have developed a greater understanding of their locality, or of the few streets to which their walks have been restricted, and are more aware of bird song or the humming of bees. A community mapping exercise would take this further, strengthening a sense of place and of community in its fullest sense, building on local knowledge, as well as adding to it, and developing the local ownership of a project that is essential to its success. Community mapping and parish mapping are well tried and widely known techniques, but they rarely focus on natural resources. The Wildlife Trusts are increasingly developing Nature Recovery Network Mapping on a county level but these projects are not community-based. In eastern Indonesia in the 1990s, the two elements were successfully brought together in a participatory community mapping project that led to the establishment of the Kayana Mentarang National Park. What we need now is a local, community-led and essentially urban equivalent. Some form of it seems to be happening almost spontaneously. The guerrilla chalking of the names of street ‘weeds’, on the pavement beside them, has taken off both in America and across Europe. In Walthamstow, in north east London, an initially anonymous chalker has not only named the street trees but added her own personal comments; ‘Sycamore – a real survivor, grows anywhere!’ and ‘London plane, my favourite, takes pollution out of the air’. A community mapping of our natural assets could include not just what’s already there but people’s responses to it, memories of what was once there, and reminders of the ways in which the contours of streets, or other landscape features, reveal the previous land use or the existence of a lost river. Such an exercise is not so much a cataloguing as a celebration. 

The promotion of urban biodiversity is not ultimately about the survival of other species so much as our own. It is about environmental services and sustainability gains, about social, physical and mental wellbeing, and about the restoration of the complex ecological web upon which we depend. Those experiences in the garden with blackbird and wood mouse at the beginning of lock down, are reminiscent of the beautiful prophetic vision in the book of Isaiah, of a world in which ‘the wolf will live with the lamb, the leopard will lie down with the goat ……and a little child will lead them.’ We’re not quite headed for that, but we should be aiming at cities designed for the mutual benefit of multiple species. And it is achievable. We could remember, for example, the transformation wrought in Bermondsey, then the worst slum in London, by Ada Salter in the early 20th century. The first woman to become Mayor of a London borough, Ada believed in a ‘socialism with flowers’, planting the streets with trees, building parks, bringing open spaces into bloom and brightening tenements and balconies with the distribution of free bulbs and window boxes. What Ada did for the cultivated species we can, and should, now do for the wild.