Connectivity of green and blue infrastructures: living veins for biodiverse and healthy cities

A morning with the Agence de Biodiversité of Ile-de-France

On a beautiful May morning, I meet Xavier Japiot, Antoine Larre and Yann Le Bourligu at an entrance to the Petite Ceinture Verte in the 19th arrondissement of Paris.

Their pleasant task this morning is to carry out a diagnostic of the fauna, flora, fungi and lichens, as well as habitat types, on a small stretch of the Petite Centure that will soon be made accessible to the public.

The Petite Ceinture Verte (Small Green Belt) is an abandoned raised railway that circles Paris, covering around 40 ha. The railway line once brought basic goods such as food into Paris, but since the 1980s it became an industrial ruin, attracting spontaneous and informal uses. The SNCF (the French public train operator) still owns the Petite Ceinture, but since 1996 it has been converting sections of it into public parks managed by the Mairie de Paris. Currently, you can walk along long segments of the Petite Ceinture in the 20th, 13th, 14th, 15th and 16th arrondissements, although they do not connect.

This section of the Petite Ceinture where we are meeting is about 200- 300 m long, between a bridge across a canal overlooking the Villette park, and a farm (https://www.fermedurail.org/) to which the city is lending space on the railway tracks. This stretch will be made accessible to people with limited mobility, for example by creating a smooth track, and the steep banks will be protected with fencing, while also maintaining at least one set of rails untouched so that they remain useable just in case. The goal of today’s diagnostic is to ensure that the amenities that will be installed for the public don’t interfere with the ecological and biodiversity value of the site. The Petite Ceinture is part of the national, regional and city Schema of Ecological Coherence (SRCE, http://refsrce.natureparif.fr/cartes?id=75115), a plan to maintain and restore ecological connections—in other words, what we call urban green and blue infrastructure.

I was so excited to have a fieldwork day that I automatically packed a small backpack with a picnic lunch and a water bottle even though we were obviously going to be in the middle of Paris (never go to the field without plenty of food and water is a lesson deeply engraved in my psyche). I would even have worn my hiking boots, if I hadn’t forgotten to fix the sole of the left boot, which had come unglued in Lesotho. I arrived a little bit upset that I was late, imagining that I was holding everyone up from starting a precision-planned day of protocols that had to be finished by a specific time. As the anthropologist Hugh Raffles describes accompanying scientists’ ecological field work in a well-known paper: “The effects of its repetition are drug-like, compelling, irresistible: a tacit, machinic logic generating its own perverse desires…it was the embodied pain of doing science that convinced me of its seriousness” [1]. Now, I'm not sure this is entirely fair as a characterization of science, since plenty of art forms also require tiring and repetitive practice and execution, and such things are much less painful if you care about them. Yet, such a mechanism of knowledge production is not something you want to mess up, and fundamentally contradict the spirit of, by turning up late. Happily, I found that the methodology of Xavier was much more akin to being a naturalist, in the line of Darwin or Theodore Stephanides (https://en.wikipedia.org/wiki/Theodore_Stephanides). To be honest, this surprised me, but pleasantly. Both the rare and the banal would reveal themselves to us through the excercise of educated and informed attention.

Xavier is the biodiversity expert. He has been studying urban biodiversity in Paris for 30 years, and works as a consultant. Antoine has clipboard with a satellite photo of the site and makes some notes on it. Xavier has a a backpack full of guidebooks and speciment bottles, and a tiny unruled notebook in which he starts jotting down the names of species from the moment we climb up the up-ramp onto the railroad. We listen to the birds singing. “Listen, do you hear that,” he says, and then we listen through intermittent construction noises as he notes the name of the species he heard singing. We look at plants. Xavier walks up to a plant and touch its leaves. Then Antoine joins him, rubbing and feeling the leaves. They point at something. One of them looks at a leaf very up close to detect the exact shape of the teeth on its edge, or the hairs on the underside, or some other detail. They agree on its name. Sometimes someone points out an insect and comes up with a name for it.

We see a dead bird along the path. “Female blackbird, you can see the brown ends of the feathers on the stomach,” says Xavier. He has kept notes on all the animals killed by traffic that he has found all around France. He then notes an Arrhenatherum elatius (a kind of oat-grass), a hoverfly (Syrphus ribesii) on a dog rose (Rosa canina), a Senecio inaequidens (a plant with yellow flowers from South Africa), a young wall lizard (Podarcis muralis, a protected species), and a Hippolais polyglotta, or melodius warbler, which migrates from West Africa and is a rare visitor to Paris, which they all observe with satisfaction through Xavier’s binoculars. “With the strap over your head!” he says to Yann chidingly. With a meandering, gentle rhythm we wend our way between one apparently random observation and another down the railway tracks. Xavier doesn't always mention the scientific Latin name of the species, but I ask him because it is easier to find the English translation later.

Xavier shows me a plant just outside the fence that a new apartment building has erected along the slope. I don’t catch its name, but he tells me it was used as bandanges in rural areas and in times of war. Following subsequent internet research, I am pretty sure it was comfrey, Symphytum officinale.

Xavier points out and discusses a “real geranium” (Geranium rotundifolium I think, based on my Flora of urban abandoned lots), another plant whose name no one can remember, a Robinia tree in flower, a yellow-flowered Chelidonium majus which produces, he shows me, a deep yellow latex that he says is used to combat warts, a small grey snail, small young plants of Senecio viscosus that are downy but also appealingly rubbery growing among the rocks, a Cymbalaria muralis with purple flowers growing in a niche in the cement, and a red and black firebug (or ‘policeman bug’, in French) (Pyrrhocoris apterus) wandering on the underside of a rail.

All of the observations that Xavier collects go into a database which used to belong to the Biodiversity Service of the city of Paris. The database contains entries for observation recorded, date, species, place, and protocol (if any). There are existing protocols for particular species, such as bats, or for the Vigi Nature citizen science projects run by the National Museum of Natural History, which also go in the database. Every five years Xavier uses these hetergenous entries to make atlases of biodiversity at the scale of each arrondisement of Paris, combining qualitative and quantitative analysis. He can make analyses of phenology (biological timing of events over the seasonal cycle), population trends over time, or outcomes of management. Both the banal and the rare are followed and analysed.

Antoine identifies a lichen, a quite banal one of the kind you see everywhere, that is growing on a slab of concrete. He explains that you can identify the lichen based on its form (crustaceous, here; see http://www.countrysideinfo.co.uk/fungi/lichens.htm), its color, the color of the reproductive elements, and the substrate its growing on. This though, is not the kind of lichen we are looking at in BIOVEINS since different kinds of lichens grow on rocks and on trees (and we look at trees).

Having contemplated the lichen and some red galls on a tree leaf, we walked back along the railway line along the side where the grass is growing. Xavier takes out his sweep net, and Antoine sweeps the grass with arcing side-to-side motions. After a dozen meters or so he flips the end of the net over its rim to trap the insects inside so we can look at them. On the first sweep, we find lots of grass seeds and a “punaise des cereales,” which is an ambiguous common name for various kinds of bugs (Hemiptera). On the second sweep we find a solitary bee, a grasshopper, and a tiny green beetle. Xavier hears a Eurasian wren (Troglodytes troglodytes) giving an alarm call. I do the third sweep. We find a yellow fly (possibly Sapromyza opaca according to my fly book), and a bug that is pale brown. Xavier can’t remember its name. “Aak!” he says. “Erm….Hm….Uf…Something in the grasses….’Wheat bug’…Something with AE” He looks it up in an app on his phone. Aelia acuminata. On the fourth sweep we find a tiny wasp of unknown species. Then we have run out of grass margin.

Xavier shows me a plant with a broad round leaf and tells me to rub it in my fingers. It smells like garlic. You can eat this, he says. Allaria petiolata. Then we come across a photographer called Francois Godard who says he has been photographing the Petite Ceinture for over 30 years (for some historical videos and his work see here: https://www.petiteceinture.org/Videos-de-Francois-Godard-sur-la-Petite-Ceinture-episode-I-avant-2001.html). He is sad that opening it to the public will take away its character as a “wild squat” and make it into a “standardized” “public square”. The important thing, we all agree, is to make sure that biodiversity isn’t sacrificed to public recreation. Mr. Godard goes on his way and we next spot a stink bug, a green beetle flying in the distance, hear the rustling of an invisible lizard, and try to approach a white butterfly that comes flying across the tracks—an Anthocharis cardamines, or orange tip, and a female as it is white. After three pleasant hours, we are done—in time for me to have a picnic in the park with my fieldwork supplies.

The management of the Petite Ceinture Verte is minimal and largely passive. Over time the understory and prairie habitats noted by Antoine on his map may turn into shrubby areas. The goal of the city isn’t to keep the Ceinture Verte in any particular habitat state, just to maintain it as a green infrastructure along which various species can traverse the city. Its not a protected area, but a corridor. Nevertheless, as succession occurs, as the plant species change and the physical structure of the vegetation is altered, which species are found there and are most likely to move along it may change. But surely Xavier Japiot will be there, zigzagging along, noting this and that in his tiny notebook for his personal lists and national databases. Thus, a body of knowledge is made, not painfully and excrutiatingly, but following the rhythms of nature itself.

--Meredith Root-Bernstein, 20 May 2019

[1] Raffles, H. 2002. Intimate knowledge. International Social Science Journal, 54(173): 325-335.