The impact of humans on the degradation of biodiversity is no longer in doubt. “75% of the earth’s surface is significantly altered by human activity. More than 85% of wetlands have disappeared. A million species are threatened with destruction. On a global scale, local varieties and breeds of domesticated plants and animals are disappearing”, warns the latest 2019 report from IPBES, the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. 

The term biodiversity “is often assimilated with all living species,” declared Gilles Bœuf in December 2013, during his inaugural lecture at the Collège de France. “But it can in no way be assimilated with mere inventories or catalogues of species.” It is “the totality of all relationships established between living beings, among themselves and with their environment”. 

For its part, the French government will provide “more than 20 billion euros” so that “by the end of 2021, all territories will have ecological development contracts”, including “concrete action plans” [such as development of cycle paths and the fight against soil artificialisation, included in the national biodiversity plan in July 2018], the Prime Minister said in mid-July 2020.
Environmental activist Rob Hopkins, the initiator of the international Cities in Transition movement, has no doubt about it: “we are going to experience the most remarkable ten years of ecological transformation in history,” he announced in Le Monde of 22nd August 2020. 

These reflections lead to the same conclusions: it is not enough to combine the traditional urban planning approach with an ecological approach, however rigorous it may be, to design a stronger, sustainable and happy city. It is a question of considering the neighbourhood or city as an ecosystem, responding to its inhabitants’ desire for nature, ethics and social creativity. The traditional urban planning project, designed by humans, “the dominant species” as biologists say, provides for the optimal occupation of urban space by developments that house its activities - housing, supplies, work, leisure - and the traffic infrastructures that structure the city. This project involves densifying the habitat, creating perspectives, conserving and restoring places or buildings of historical value. 

This dual approach - urban planning and ecology – “tends to instrumentalise nature in the name of biodiversity”, warns Emeline Bailly in Biodiversité urbaine, pour une ville vivante (2019). “A manufactured, highly technical nature - with its plant façades, its flat roofs with thermal properties, its valleys - is being deployed to remedy the ecological ills of metropolitan areas: the fight against pollution, against heat islands, better control of the water cycle, etc. These ‘green’ innovations are marketed in cities (...). Nature is then reduced to a technical solution to the detriment of nature projects that promote biodiversity and adaptation to climatic hazards”. 

“The loss of a strong relationship with nature would create a form of urban pathology,” says sociologist Dorothée Marchand. “If the town is sick, it’s because we’re sick ourselves.” “There is no sustainable health if it’s not ecologically based,” Robert Barbault wrote in 2006. 
Anthropologist Sonia Lavadinho observes, “Trends are emerging to invest the city from the outside, to multiply interactions with others and with nature, to bring to life an ecosystem in which it is possible to diversify uses, decompartmentalise professions, connect diverse populations and reinvent the habitat.” A biodiverse, healthier and more creative city is within reach. 

But the movement is launched and solutions are falling into place, generally supported by elected officials and building professionals, while promoting the decompartmentalisation of services, citizen consultation and solidarity. “It’s not a question of giving in to fear, but of seizing an opportunity to give new creative impetus to urban planning and architecture, while promoting a social momentum,” explains Cyril Trétout. The Act of 13th December 2000 on solidarity and urban renewal (SRU), the Grenelle Acts of 2009 and 2010, then the Act on access to housing and renovated urban planning in 2014 (ALUR), prescribed respect for the environment in the development of a neighbourhood or the construction of a real estate project. City professionals must in particular respect the rules of densification, integrate green and blue corridors, and provide local services to avoid unnecessary travel. 

3D CORRIDORS
In order to link the corridors to one another and to the reservoirs of biodiversity constituted by wastelands, green spaces, parks, cemeteries or zoos, maintained without chemical treatment since the Labbé law (2017), proximity corridors are developing on the ground (dotted lines, in “stepping stones’ when it concerns planted trees), under the impetus of “Canopy Plans” voted by more and more cities, such as Milan and Strasbourg recently. But these proximity corridors also climb along façades, on roof terraces. 3D forests invest in projects such as Stefano Boeri’s Bosco Verticale in Milan. The vegetation of Mount Revard should soon run over two buildings erected on the former national thermal baths of Aix-les-Bains, a refurbishment project by Vincent Callebaut, which was acclaimed by the inhabitants.

“For real estate transactions aiming at a level of excellence in terms of sustainable construction, ecology and brand image”, in France, the International Council on Biodiversity and Real Estate (CIBI) launched the BiodiverCity® label, “a standard as well as a strategy and an accreditation.” It encourages initiatives such as nesting boxes on the walls or roofs of buildings, local bio-sourced materials, and the greening of buildings by local species. In addition, the CIBI has just launched the BiodiverCity® Ready label for development projects, a tool for assessing and promoting the consideration of biodiversity at the neighbourhood level. 

In France and the United States, with the help of associations, more and more municipalities are organising workshops to explain the difference between decorative vegetation and vegetation that reinforces biodiversity, to raise awareness of the charm of ordinary nature and the virtues of small fauna. In order to better understand and count it, the OFB has launched a call for projects to create a Communal Biodiversity Atlas (CBA). The “Green Living Program” in North America encourages neighbours in the same neighbourhood to green it in a virtuous way.

In Nantes, the municipality is transforming public gardens into fruit gardens, the production of which is shared with the birds. Urban farms are multiplying; Paris has about twenty of them, including the largest in Europe. In Tours, a citizens’ initiative wants to transform the city into a communal market garden, in the wake of the worldwide “Incredible Edible” movement launched in 2008 in a small town in England, but without municipal authorisation. “Citizens, citizens, let’s resist, let’s sow seeds,” a watchword relayed by Le Monde of 24th July, 2020.

EVALUATION 
The quality and sustainability of the systems put in place have yet to be assessed, to check whether more species interact favourably with each other. 
In Berlin, they are “quantifying biotic factors”, testing what living things do to living things in the city, in green spaces, wasteland and buildings. The function of the CityScapeLab experimental platform is to modify and anticipate the effects of urbanisation on living organisms and biodiversity, using networks of sensors that measure all environmental parameters (temperature, pressure, humidity, luminosity, particles, noise, etc.).

CROSS INTERVIEW, with Cyril Trétout, architect and urban planner, president of ANMA, Sonia Lavadinho, anthropologist, founder of Bfluid, Pierre Audiffren, ecologist, geographer, founding president of Chic-Planète Consultants.

Pierre Audiffren, is the protection - and restoration - of biodiversity a given for those involved in urban planning?
P.A.: No, because most of those involved do not yet understand what the word biodiversity means. On the one hand because of a common confusion between nature and biodiversity. Fostering biodiversity, for the most part, means reintroducing nature to the city. But that doesn’t really make sense, because the living world is already there, ready to flourish if given the opportunity, in particular by reconnecting disjointed spaces. People said that the lockdown brought animals back into town. They were already there, but they stopped hiding when the urban movement subsided.

Cyril Trétout, how does the environmental approach condition your job as an architect-urban planner?
C.T.: The environmental approach forces us to consider all aspects because, when I am about to draw something, I have to look at the ecological impact it will have. So it’s the site that makes the project and not the other way around. The sun, the wind, the people who live there or have lived there, the memory, all this makes up the urban or architectural project. The project is built from the bottom up. It’s anchored in a reality. 

We must therefore rethink the way in which building permits are granted. The constraints of financial optimisation should not be a priority. On the other hand, those imposed by the nature of the site must be a top priority. We need to take the time to carry out preliminary, indispensable and exciting studies, such as the one we are currently conducting on the Brière marsh in Saint-Nazaire. 
What is positive is that it invites us to work with the intelligence of others, from other fields (ecology, home automation).

When we talk about “construction”, we are talking about 1% of the housing stock in France. Under these conditions what should be built should be exemplary, because it only represents 1%. Half of this percentage, however, is made up of single-family homes. The idea was promoted, with unbeatable costs and deadlines, that Monopoly houses were a response to a legitimate desire for comfort and greenery. The average city is getting denser and construction actions are not up to the level of comfort desired. 
How can we reintroduce this comfort desired by everyone - of which biodiversity is a part - into condominiums? I believe that the industrial heritage should be refurbished to meet these aspirations. But who pays for the asbestos removal? The clean-up? How do we finance the refurbishment of abandoned heritage? 
Furthermore, I believe that more attention should be paid to our streets as a matter of urgency. 

But there is another trend, a strong return to the outside city, which is a way of first inhabiting your body, of making it move outwards. The house is a hybrid of indoor and outdoor spaces such as the “outdoor kitchen” and “rooftops”. Lockdown in the city has increased a strong desire to get out, to live in the street, the city from the outside. 
Studies show that as soon as you put more nature in the city, people get out and interact more. Yet in most of our French cities, no sooner have you set foot outside than you feel like evaporating. It is the responsibility of everyone (including politicians and town planners) to build a city from the outside, that we can also live inside. 

In the next 400 and 500 m, you should find the answer to your daily needs, in a setting that also allows you to pause, take a breather, make a phone call, wait for the end of your child’s piano lesson, for example.
We have invested massively in places that we only visit once or twice a year, far from home, but we do not know how to make pleasant places to spend 5 to 15 minutes, places that we visit every day. This is the challenge of the coming decade: to offer people, within 500 metres of their homes, spaces where they can enjoy nature when they have a moment. In this respect, Denmark and the Netherlands have much better control of their land than France to create an everyday city, which encourages interaction and human biodiversity, a sensory and experiential city, for all ages, in all interactive relationships (in the family, at work). 

Pierre Audiffren, how can we encourage this trend towards living in a city that respects biodiversity? 
P.A.: First by changing lifestyles. I’ll give you an example of the inconsistency that prevails. In my region, a mayor wanted to set up shared gardens but nobody was looking after them. So he thought people didn’t know how to garden. He planted the gardens shared by gardeners. But no one harvested the fruits and vegetables. Why? Because the people in the neighbourhoods where he had set up the gardens did not know how to cook or did not have the time to do so, because of the frantic pace to which they were subjected. And yet they liked the idea! We have to change our relationship to time, change pace, slow down, walk, take our bike, inhabit the space, appropriate it, share it.

Finally, understand that it is not difficult and that this paradigm must be systematically integrated into urban development. Nature invites itself easily into the city, if it is given the means; in the large families of plant and animal species, it is like in human families: one will be adventurous, the other will love the city, the other the countryside... There is no need for major adjustments to allow each animal or plant, if they invite themselves into the city, to live out their respective daily, seasonal, multi-year cycles. All it took was for a friend of mine to plant a few local species in his garden, including a hazelnut tree, to bring in a red squirrel. It is these unexpected gifts of nature that make you happy!