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


Ruins are poignant because they point to a loss of use, activity, life—and value.


Ruins are entropy in action, the natural recycling of materials back into nutrient and mineral cycles. Buildings, and gardens, become ruins and wastelands when they are no longer cared for. Yet, the discovery of a ruin—like the discovery of the secret garden in the eponymous book—can generate new engagements of care and forms of value.

Perhaps what also fascinates us about ruins, what makes us sometimes prefer the disintegrating monument to the well-preserved or the new one, is the unpredictable mixing of nature and culture that seems to contradict our inherited ideas about these being two, contrasting categories. As Michel Makarius puts it in the introduction to his book “Ruins: Representations in the art of the Renaissance to our time”, “When we discover the disorder of monuments sunk where ivy and blackberry mix with broken stones, and the tree, the hill and the sky are framed by the gaps of broken walls, it seems to us that a subtle perfume is floating through the air, spread by the spirit of the place” (my translation). Ruins, as he points out, came to be understood in the Renaissance as sources of learned knowledge, comparable to the ancient books that were being retranslated, recopied, and eventually printed. The relations between nature and civilization were understood in particular ways throughout history (not be mention between cultures). Ruins have classically, in Europe, been sites where the brevity and vanity of human achievements and glories are contrasted with the eternal return of nature. As plants, animals and soil take over cathedrals, gardens and palaces, commentators have often commented on the struggle between civilization and wild nature, and their different temporalities. However, what we read in ruins has changed over time.

Today, when we see industrial ruins, abandoned lots, brownfield sites, or urban wastelands, we may be more likely to think about urban renewal and the coexistence of nature and cities. Abandoned buildings and brownfields are often taken over by voluntary associations, developing ad hoc communities of social aid, artistic workshops, or urban gardening. These activities and communities often form during the temporal gap between abandonment and a city’s urban renewal projects finding developers. Thus, some workshops, shops and the object-swapping depot of the former freight yard called Godsbanen in Aarhus, Denmark ( are slated to become an architecture school (, the old public baths taken over as an artists’ cooperative near my apartment in Paris is being rebuilt as a micro-housing site and coworking office (, and the social solidarity, art and enterprise community of Les Grands Voisins in an abandoned hospital (, also in Paris, will become an eco-neighbourhood (
Certainly all of these new projects sound like exemplary urban planning with gardens and environmentally responsible construction, but perhaps there is also something sad about the erasure of the spontaneously and gradually developed modes of caring about ruins and the formation of community values through social and artistic programmes. Ruins, again, tell us about the ephemerality of human projects.

Gardens can be a way to value urban wastelands in ways that are less transformative, and maintain deeper traces of the long histories of use and disuse. There are various aesthetics and approaches to converting urban wastelands into gardens. Two different abandoned railways in Paris have been turned into very different kinds of gardens, both very attractive in their own ways. The Petite Ceinture, as it goes through the 15eme arrondissement of Paris, is managed to maintain natural brownfield habitats ( The Coulée Verte René-Dumont, also a railway line converted into a park, is largely maintained as a typical public garden with flowers and other ornamental plants ( Both are very nice spaces. An interesting approach that minimizes transformation while revaluing space, has been developed by the landscape designer and gardener Agnés Sourisseau, who has used plants and urban gardens to restore various abandoned urban and industrial sites in France. For a very interesting talk on her work (in French), see this video: Ruined ancient gardens may also be rediscovered, with new communities of gardening forming within them—such as the Queen’s Garden (Le Jardin de la Reine) which I came across in Montpellier. This botanical garden dating from 1595 has been taken charge of by a citizens’ group in order to prevent its sale by the city— a goal that was achieved in 2018 –resulting in many citizen-led activities in the garden (

But of course, let’s not forget about the plant and animal communities that make ruins and brownfields home before they are re-colonized by humans. In the UK, biodiversity experts have worked to come up with standards appropriate for assessing the biodiversity value of brownfield sites. An interesting view is that many rare and endangered invertebrates are found in brownfields because these act as refugia. Such species have been driven out of “nature” by agriculture, and survive only in abandoned industrial lots in cities! Ironically, biodiversity compensation plans may include recreating brownfields de novo in specified areas, to compensate for urban renewal projects.

Biodiversity experts often need to turn to local natural historians to understand urban brownfield biodiversity. The handbook “Natural History of Vacant Lots” from the California Natural History Guide series suggests a range of investigations and observations that one can carry out in a local abandoned lot in order to identify species and their ecological interrelationships. As the authors write, “Change is one of the more obvious phenomena on disturbed sites..” (p. 30). Or, as the Guide to the Wastlands of the Lea Valley (sites that would be developed for the London Olympics) puts it, “The Lea Valley was once a centre of industry; for the moment it is home to wastelands…Because they have been left alone, natural processes of decay, and entropy—processes that affect all places but which are hidden in the rest of the city—can be observed. They are in-between places where almost anything is possible, where time seems to have stopped.”

Thus, the species most common to vacant lots and other urban wastelands are ruderal plants and invertebrates and vertebrates well adapted to disturbed and early-succession habitats. It is important to remember that disturbances—such as fire, large plants falling over, erosion, rock falls, soil being turned over by digging, trampling, intense herbivory, and so on, are all natural processes that can occur at low, medium, or high densities. An urban wasteland may resemble a highly disturbed or degraded natural habitat, due, for example, to hard concrete or asphalt surfaces, exposed soil, lack of a tree canopy, and so on. Succession is also the natural ecological process through which new habitats (for example, soil formed after a volcanic eruption, or land exposed after a change in sea level), or recently disturbed areas, develop new species communities over time. These changes occur as ruderal or disturbance-adapted species change the habitat through their growth and other activities, creating new niches for a new set of species. For example, trees create shade, which both plants and animals need, and help form soil through leaf litter. You can observe ruderal and disturbance-adapted communities, and the processes of succession that they facilitate, in your local urban wasteland or ruin. Keep notes on your observations, and one days these may be valuable data.

Paradoxically, urban ruins are sites of renewal. The ancient wisdom and moral lessons that we read in them might today be about solidarity, flourishing and regeneration. Natural processes that create value—successional processes creating habitat niches for many species, or curious urban residents creating communities of care and creativity—materialize out of the slow recycling of past practices of construction.

Further reading:
Vessel, M.F. Natural History of Vacant Lots. University of California Press, Berkeley.
Almarcegui, L. 2009. Guide to the wastelands of the Lea Valley. Barbican Art Gallery.

--Meredith Root-Bernstein

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