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"Think Like a Forest" | ArchiLectures | Politecnico di Milano | 14.11.2018

Trees, bushes, briars, nettles, humus, worms, shadows, shafts of light, ponds, mushrooms, ants, birds’ nests, deer, boars, snakes: the forest comprises a rich and varied ecological community, but even more it is the site of eternal growth, and reciprocal decay, what Lucretius in De Rerum Natura called mors immortalis. For my purpose, however, I propose that the forest represents the primordial boundary. The darkness of nature juxtaposed to the light of the city. The organic versus the inert. This distinction marks the essential difference between the freedom of nature and the constrictions of society.

Despite the elation at the demolition of the Berlin Wall in 1989, and the new fluidity gained from the borderless frontiers of the countries in the European Union, currently walls of separation are starting to return. Humans in most areas of the planet are at present experiencing a major contradiction, the simultaneous blurring of boundaries and their reactionary reconstitution. While the digital revolution has virtually smoothed over questions of access across the globe, the political atmosphere of nations, fueled by pent up racism against immigrants, has led to the generation of new walls. First there is the 700-km West Bank Barrier, built by the Israelis at the beginning of the millennium, conceived as a deterrent to terrorism. More recently the promised Trump Wall that the 45th president of the USA would like to extend roughly 3,200 kilometers at a cost of $25 billion to discourage the arrival of new-comers from Mexico and other Latin American countries. Europe is not fairing much better, with Hungary stiffening its borders, and Austria, Spain, and France aggressively curtailing the access of immigrants and refugees. While in 1989 there were only 16 national walls, at present they number 65 worldwide, including several in Europe: Spain has fenced off its territories in Morocco, Hungary has raised fences against Serbia, Bulgaria against Turkey, Greece against Turkey. Farther away we have India isolating Bangladesh.

The recent incident of the Dutch NGO ship Aquarius, which was refused entry into Italian ports with the lame excuse that it was not an Italian humanitarian mission, demonstrates the collapse of tolerance that has accompanied the new right-leaning populist government. The incident has served to foment Italians’ fear of the other, and brings with it a promise of new fortified boundary lines. Yet a country like Italy, with such a low birth rate, has a great need of new-comers. The reinforcing of political boundaries not only contradicts the basic human need to move, it ignores the ecological essence of the land. Countries, especially when they are led by racists, do not understand how to think like a forest. In the US Pavilion at this year’s Venice Biennale, one of the displays produced by Teddy Cruz describes “Mexus”, explaining how the imposition of the Trump Wall will countermand the delicate fluvial ecosystem of the region shared by Mexico and the US. Forests, rivers, and mountains do not recognize the arbitrary national boundaries that are becoming so restrictive, which is why I would like to propose the virtue of thinking like a forest.

To begin I would like to consider the forest of Chernobyl as an example. After the 1986 disaster a 30-kilometer radius of confinement was declared, half in the Ukraine and half in Belarus, but neither the diffusion of radiation, nor the new growth of trees with its mutant wildlife conformed to its perfect circle nor to the existing national boundaries. The abandoned city of Prypiat has been invaded by vegetation and animals, with tree shooting up through the melancholic Ferris wheel, left to grow free in this dangerous zone of confinement. Just in the recent months the largest building in Europe was completed at Chernobyl, an immense canopy that has covered the damaged 4th reactor before the concrete sarcophagus was completely eroded. This gigantic prophylactic, the bottom line of European security, boasts the largest span of any building in Europe at 270 meter. If religion is usually concerned with human salvation, I can think of no better setting for a new global cult. While the vault is not reminiscent of temples, considering its function and scale it should attract in this wooded sanctuary all of our hopes and fears. Instead it is known by the very rational name of NSC New Safe Confinement—a literal entrapment, the ultimate boundary. Despite such an effort to isolate it, the forest surrounding it ignores the official limits.

My slogan “Think Like a Forest” is a recycling of the title of a short chapter by the great American ecologist Aldo Leopold, who wrote “Thinking like a Mountain” (The Sand County Almanac, 1949), which dramatized how urban populations make no consideration for the ecological dynamics of the wilderness—in this case exterminating wolves, which increased the deer population which in turn devoured the flora of the mountain, leading to its pathetic desolation. If we could “Think like a Forest” we might begin to sympathize with natural boundaries—indeed in the entomology of the word forest, as Robert Pogue Harrison so astutely reminds us in his book Forests, the shadow of civilization (1992), we find the connection to “outside,” a link still found in many European languages, such as the Italian “forestiero” meaning outsider. In philosophical terms the forest remains outside of the rational realm, which ascribes to the rules and laws of the city.

The forest habitat precedes human life, a living environment that provided the common ground, the first resource, for the dominant species to later emerge. And from the start we recall that forests transmit a fundamental fear that often is counteracted by fire or destruction. While trees will always grow back, they take time, from 10 to 25 years, to mature, and often human civilization has another agenda for the land, such as parking lots, suburbs, shopping malls, agricultural fields, mining. But during the past two decades the world powers, those who agreed to the Cop21 ultimatum, have become aware of the dangers of Climate Change, and the question of whether the forest can be conserved has become imperative. Forests provide natural barriers, and can be appreciated aesthetically, but beneath this they offer the promise of planetary salvation. Trees, which cover about 30% of the land mass on Earth, are the greatest producers of oxygen and the greatest absorbers of CO2 and other greenhouse gasses. While we love them for their natural beauty, we must realize how essential forests are to both local ecosystems and the global ecosystem. The watersheds of large cities, for instance, are usually guaranteed through the maintenance of forests. Both the expansion of agricultural and the spread of urban development threaten the health of forests and their watersheds. More dramatically forests fall prey to fires, often deliberately set by arsonists. Brasil in 2016 lost 3 million hectares of forest, mostly to fires, about an eighth of the world total. The planetary impact of such a loss is tragic. Portugal in the same year lost 4% of its forests to fires, and the next year did much worse, losing roughly 15% of its forests. Roughly .02% of the world’s forest are consumed by fire every year, which is cumulatively a disaster.

While I strongly advocate vigilance in the maintenance of forests, my objective here is to take the slogan of “Think like a forest” in another direction, toward urbanism and architecture. The relationship of forests to cities may at first seem antagonistic—following the Vitruvian fable that the discovery of fire and architecture resulted from the clearing, and burning, of the primordial forest. The city developed as a stronghold against the wilderness of the woods. With the modern rise of the urban, which progressed from 10% at the beginning of the 20th century to over 50% today, the increase in metropolitan growth carries at once a new potential for human consciousness-- in that cities imply a form of collective education--while also harboring an even greater possibility of augmenting the planetary carbon footprint, since urban dwellers individually consume greater quantities of energy and goods. It is commonly agreed that 40% of greenhouse gasses are currently attributed to buildings, infrastructure, and urban life. If the trend to urbanize continues, and the high entropy way of life comes with it, it will be very difficult to limit the increase of temperature to Cop21’s 1.5 degrees Celsius. That is, unless the city serves as an enlightened regulator, a place of education and civility. If the city extends a kind of control over resources and above all over mentalities, it could be the best chance to deter climate change. At the moment, however, over half of the so-called urban dwellers on the planet do not really live in cities, but rather in an expanded urban realm such as Los Angeles, Lagos, or Shenzhen. The situation of sprawl in wealthy countries and that of favelas in poor ones precludes the sort of civic order that would lead urban dwellers toward a new ecological engagement. If as Le Corbusier learned on his Voyage to the Orient, that when you build you should plant a tree, we could go further and advocate reforestation wherever there is urbanization.

To propose the forest as a means of mitigating the effects of the city, and thus to replant the city with trees and bushes, we can notice that artists got there first: Alan Sonfist’s “Time Landscape” in downtown NYC, 1978, a typical urban lot conceived as a natural sanctuary, which he surrounded by a fence and planted with the native species that previously grew on the isle of Manhattan; Joseph Beuys’ “7000 Oaks,” in 1982, his final project begun at Kassel Documenta 7 to leave the most durable of trees as a legacy; Giuliano Mauri’s “Cathedrale Vegetale” in the Parco Sella, 2002, which provides an architectural manipulation of living trees. Replant trees and the world will return to nature. Forest and forestiero will start to realign with each other.

Despite the increase in urbanization, there is a commensurate increase in empty space, pocket deserts, which Gilles Clement celebrates as the Third Landscape, but which often remain as very unpleasant patches of degradation. So many of these voids could be artfully reforested. In this quick survey I consider three ways of replanting the city: planting buildings with trees, planning cities within the forest, and finally creating a forest in urban contexts. While the wisdom of three generations of ecological planners promoting the three R’s, to reduce, recycle and reuse, remains the best way to contain the ecological footprint, we should also recognize Replanting as one of the R’s. Cities could start thinking like a forest with more active plant life amid their inert forms.

I first started noticing the potential of replanting voids in Seattle at Lawrence Halprin’s Freeway Park (1972) a concrete tapestry of several acres stretched over an 8-lane freeway. The park is intensely planted with tall trees, some of them sequoias, where the freeway plunges into the downtown. The foliage and the fountains help compensate for the noise and pollution of the road while offering an uncanny public amenity both for recreation and for using a pedestrian access from one side of the freeway to the other. The experience was duplicated with great finesse in the many parts of Barcelona during the 1990s when the Ronda ring road was completed and includes Ruiz Sanchez’s Parc de Poblenou and Roig /Batlle’s Parc Trintat Vella.

While in a previous age one of the major forms of maintenance was to keep plants from growing on buildings, today a new trend has emerged to design buildings for planting. This requires new technologies of isolation from humidity and water redistribution. The Viennese artist Friedensreich Hundertwasser should be acknowledged as the forerunner of this movement, completing Hundertwasserhaus in 1984 after a decade of negotiations. This eccentric project, which has vegetation sprouting out from all of its openings, was followed by more conventional works, especially the Argentine émigré Emilio Ambaz’s Fukuoka Municipal Building, 1994, a 14-storey building that that steps back each floor, leaving heavily planted terraces, resulting in the southern elevation slope appearing like a hillside woods. The Swiss architect Mario Botta, enamored of the tree-topped medieval Torre Giunigi in Lucca, has frequently placed a tree on top of his projects, including the Cathedral at Evry, which has a crown of small lime trees, whose growth has to be stunted through careful pruning. Probably the most visible recent project planted with trees is the Bosco Verticale in Milan by Stefano Boeri, and Barreca/LaVarra (2014), two residential towers in the new Porta Nuova renewal area planted with over 20,000 trees and bushes on its balconies. The residents are obliged to sign a contract to never touch the vegetation, which is regulated by computers for irrigation, using rainwater gathered from the roof, and is carefully pruned, both roots and branches like bonsai trees by professional gardeners. Renzo Piano’s recently completed Tribunal tower on the edge of Paris (2018) rises 40 stories with four sets of open terraces that are generously planted with trees, which in this case are allowed to grow more naturally. The problem with trees on buildings, of course, is that they have roots that are seeking depth and need a minimum of 4 meters to feel comfortable. Much of the neurological intelligence that Stefano Mancuso in Brilliant Green (2015) attributes to plants resides in their roots, which should have freedom to move. The architect who has best perfected planting buildings is Vo Trong Nghia (VTN architects) who has made a name in Vietnam with works such as the Tree House residence in Ho Chi Minh City (2014).

Extensive green roofs for small succulent plants are not quite like a forest, but indeed are more efficient in terms of structure and capacity to absorb CO2 and rain water. Needless to say they are less spectacular than roofs with trees. The Messe convention Center in Basel, recently expanded by Herzog & de Meuron has the largest green roof in Europe, incorporating photovoltaic panels with succulent plants. It is part of a city-wide program offering incentives to plant as many roofs of the city as possible. More like an aerial prairie than a forest.

Green roofs can also serve for urban farming: the Dakakker roof on a 12-story office building in Rotterdam was prepared as part of the 2012 Biennale and is still being farmed as a demonstration project. More ambitious is the Brooklyn Grange rooftop farm, begun in 2010 which cultivates 2.5 acres of roof, using a special light soil. It was launched as a private business and makes a profit selling many tons of produce and over 1,500 pounds of honey per year. Even the leading digital moguls of Silicon Valley are trying to demonstrate their solidarity with the greening of the city. Facebook hired Frank Gehry to make their new headquarters in Menlo Park which resulted in an immense green roof, quite unlike any other Gehry project. The Apple headquarters is more high-tech, designed by Norman Foster Associates. A ring covering several blocks of Cupertino encloses a small bosque and prides itself on producing all of the energy its consumes.

While these efforts to green the city offer some relief, in many cases they can be accused of green-washing, in that the energy it takes to build and maintain them (their embodied energy) is often greater than the environmental benefits they will yield. And that the consumerism they encourage counteracts the good they might have achieved in the workplace. Yet green washing is preferable to grey washing, which the current US president had proved to have such talent, and these works that purport to do good, function admirably as propaganda not only for those who have paid for them but for the discourse of arresting climate change.

In terms of hierarchies it is more important to use forestry as an integrating factor in planning cities. There have been some remarkable efforts to urbanize using the forest as the first condition of a plan. The Woodlands on the edge of Houston was planned during the 1970s as part of the American New Towns program with the advice of Ian McHarg, the Scottish theorist, whose book Design with Nature (1969), invited the Postmodern generation to reconsider planning in terms of natural ecologies. All of the water courses were conserved and home builders were obliged to respect the existing trees on their sites. While the effect on the environment was excellent, the plan made no attempt to reconfigure the suburban way of life, and thus the residents lived at great distances from their daily needs and continued to make an average of nine car trips per day to work, school, recreation, and shops, in effect negating any ecological advantage they might have gained through urbanization.

A much better example of working with nature can be found in Freiburg, Germany, where the Black Forest, since the city’s founding in the 12th century, has been invited to touch the historic center, a five-minute walk from the cathedral. This long-standing awareness of the relationship of forest to city conditioned the plan for the new suburb of Vauban, a ten-minute tram ride from the center city. Set on the site of the French military barracks used during the post-war occupation, the new district for 5,000 residents is one of the most demonstrably eco-friendly neighborhoods in Europe. To the east is a hill and the entry to the Black Forest and to the south a wooded stream, mixed with allotment gardens forms a natural boundary to the district. The northern and western sides are bounded by roadways that mix with adjacent neighborhoods. Vauban has two public plazas, the residents all live within a five-minute walk to public transportation, there are schools and shopping in the settlement and there is a strong disincentive for woning automobiles, a 17,000€ yearly fee. Officialy only 22% own cars. Many of the buildings produce more energy than they consume and the local power plant uses wood chips from the local forest for its co-generation energy and heating. In this case the balance between forest and urban is symmetrical.

One can design within an existing forest but one can also design a new forest, which after a 25-year period will become autonomous in its development. The Südgelände park in Berlin offers a remarkable reuse of an urban void, and at first sight seems that if you let it grow the forest will return. But it has been orchestrated in the abandoned train yards west of Templehof over the course of 25 years to feature a spontaneous forest that grew up amid the switching tracks and abandoned equipment. The area was installed with colored walls, inspired by the Mexican architect Luis Barragan, placing monochromatic planes amid the machines and trees to great aesthetic effect.

Two final cases demonstrate how think like a forest can truly change a city. The Oasis of Focognano on the edge of Florence, an 80 hectar area set between the factories of high fashion and the A1 Autostrada was conceived 20 years ago under the guidance of Carlo Soccianti. Using funding for catchment basins and indemnities for the destruction that buildings have caused to wildlife he has bulldozed what once were industrial agricultural fields to create a forested wetlands, where birds are protected from humans. It is not a public park, but a place that humans can only visit with a guide, taking a vow of silence and vegetarianism during their stay. The beauty of the lakes, plants and animals within view of the Duomo offers a new organic underside to Florentine sprawl.

Milan, which is the most urban Italian city, center of industry, culture, and finance, is surrounded on its southern ranges by rice fields and left-over farms, known as cascine. In 1990 the office of the Parco Agricolo Sud PASM was established in the effort to propagate the worls first Agricultural Park. It covers 60 different municipalities, but as yet has not realized its potential. One of the cascine, San Roman, however, was developed from 1972 by the Ialia Nostra association and volunteer labor, requisitioning municipally owned fileds and turning them into a forest, the Bosco in Città. The park, a stone’s throw from the San Siro stadium has become a major source of hands-on environmental education. Where previously there was not a single tree, today it is planted with many thousands of trees, which have started to regenerate the forest on its own. Aside from its forest trails, canals, and new wetlands, the Bosco in Città harbors a bee-keeping school and about 200 allotment gardens. It demonstrates how replanting can become an important component of the reorganizing of large urban environments and help educate the city and the individual toward more virtuous life-style choices.

© Richard Ingersoll

TerraViva Competitions

Recently created as a new branch of "TerraViva", this specific section proposes a series of design competitions in line with the topics addressed by our workshops and mainly directed to architecture students, new graduates and young designers.

TACTICAL URBANISM NOW! 2021 - The Reappropriation of Public Space will be the third competition of 2021. Starting from December 13th, registrations will be open until 18/03/2022.


December 13th "Tactical Urbanism NOW! 2021 - The Reappropriation of Public Space"; 10.000€ in Prizes; 10 Honorable Mentions; 30 Finalists; Submissions within 18/03/2022; Results on 26/04/2022; Jury:  Miralles Tagliabue EMBT (Barcelona), Public City (Winnipeg), Openfabric (Rotterdam); Orizzontale (Rome); Intuy Lab (Lima); Sports (New York); Atelier Nea (Paris); OBBA (Seoul);


September 10th "Hangar Ticinum - A Community Hub on the River"; 10.000€ in Prizes; 10 Honorable Mentions; 30 Finalists; Submissions within 10/12/2021; Results on 20/01/2022; Jury: Piuarch (Milan); TSPA (Berlin); Stefano Boeri Architetti (Milan); Operastudio (New York); Degli Esposti Architetti (Milan); Untitled Architecture (Moscow); Comune di Pavia (Pavia); Politecnico di Milano (Milan);

March 15th "The Living Museum - Micro-Architectures in the Landscape"7.000€ in Prizes; 10 Honorable Mentions; 30 Finalists; Submissions within 01/08/2021; Results on 13/09/2021; Jury: Topotek1 (Berlin); Elemental Architecture (New York); Stefano Boeri Architetti (Milan); Paredes Pedrosa (Madrid); NADAAA (Boston); One O One Architects (Seoul); Nicolas Campodonico (Rosario); Studio O (Berlin);

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