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Ecology and Urbanism


Part 1

As we increase our focus on ecology, both at the architectural and the urban scale, it is useful to recall the concepts and theories that guide our research and practice. The first concept we want to explore is ecology; we even call ourselves ecological, and we like ecological thinking. But what exactly is ecology in urbanism?


In the context of urbanism, the word Ecology has several meanings. Urban designers and architects sometimes simply adopt concepts or models of ecological derivation; other times by pluralising the term "ecologies" some describe the relational aspects of the social, spatial, morphological structures they are investigating. Ecology has supplanted the word “environment” as a richer concept embracing relational dynamics between elements of the environment and man. There are, therefore (at least) three definitions of ecology. First, "hard" ecology is a scientific discipline that investigates ecosystems and the effects of actions on ecosystems (including human beings) as well as the different forms of disturbance, decay, pollution that affect ecosystems.

Second, the variety of spatial and thermodynamic relationships that occur in different environmental contexts are defined as "ecologies": a term that replaces and integrates the word "habitat", which instead limits itself to describing only the environmental conditions, leaving out the plurality of relationships that they can trigger with the dwellers. Ian McHarg, the founding father of the discipline, spoke about human ecologies.

Third, a plurality of ecologies defines different ways of interpreting the hybridisation between biological, urban, planning theories and models, which are redefined in a dynamic, relational and processual sense in an attempt to develop more effective interpretative and conceptual models: an urban ecology, human ecology and ecological or environmental planning, whose definitions are less clear and established, but highlight a struggle to find solutions to several complex problems related to the environment. The process is circular: laboratory ecology also acquires terms and metaphors from other disciplines.


The origins

Ecology has established itself as a science and has produced relevant results since World War II. Until then, it has been investigated and interpreted within a multitude of disciplinary contexts: biology, geography, sociology, botany, and ecology have composed, a diverse conceptual archipelago, on which various urban planning theories have been developed. Until the early twentieth century, unconventional figures of planners and designers (biologists, agronomists, botanists, sociologists by training) fueled the debate on the role of man in nature and on the relationship between society, city and the environment.

The processual and dynamic nature and the focus on relationships are the characteristics that have defined ecology since its foundation. The affirmation of the evolutionary theories of Darwin and Von Humboldt has allowed overcoming the classic taxonomic definition of organisms based on their physical structures to identify the functions and mechanisms that enable their survival through relations with the environment. The first definition of ecology dates back to 1866, by Von Haeckl as the "study of the economy of nature and the relations of animals with the organic and inorganic environment, above all of the favourable and unfavourable relations, direct or indirect with plants and with other animals ". The pivotal change here is that the focus shifts from the physical structures to organization, in other words, relations. Along this line, which tajes into account the competitive nature of evolution and adaptation mechanisms, the nineteenth-century studies on plant and animal communities are developed. Organisms, adapt to fit the organized system of life as efficiently as possible: their fitness measures their ability to survive. Following this principle, early ecologists imagined that that the entire organization of life tends towards efficiency and equilibrium through the progressive adaptation of organisms. Their linear and incremental vision of natural processes did not yet take into account the possibility of disturbance, imbalances, and the processes that govern change. Ecology is, in its initial phase, research and affirmation of nature as order and progress.


In 1905 Frederick Clements developed the theory of plant succession, understood as a natural tension towards a state of maximum efficiency, defined as a climax; the idea was subsequently questioned (see Ecology laboratory 3). Clements also coined the term "ecotone" which describes the edges and points of contact between different plant communities; tone indicates a state of tension between different biochemical conditions, which manifests itself in the greater biological richness of these areas.


Ecology and Planning

Environmental awareness and the socio-ecological idea of the city have a double origin. First, between the eighteenth and nineteenth centuries, the idea of man's dominion over nature, with all its religious had religious and philosophical roots, was contested by romantic thinkers and artists. The writings of Goethe, Emerson, Thoreau describe the dynamic beauty of nature, highlight its thaumaturgical properties and allude to a moral value of natural laws. The return to nature, as a physical place for the rediscovery of original values was the bee big thing.

A second origin can be traced back to the critique of the industrial city, both as a living environment and as a physical representation of the capitalist development model. George Marsh first enunciated the concept of imbalance and contrast with nature due to economic development. In 1866 he maintained that the role of human beings should be that of "co-workers with nature in the reconstruction of its damaged fabric”: a recognition of the damage caused by man's opposition to nature. In the United States, the conquest of the western frontier would come with the almost complete depletion of midwestern forests, resulting in environmental disasters such as the "great dust bowl". The subsequent intensification of disastrous episodes and the highlighting of the relationships between cities and natural resources inspired the work of environmentalists such as Jhon Muir and of technicians such as Gifford Pinchot and Aldo Leopold. They "will support and inform the" philosophies "of management and planning of federal agencies and national parks, of wild fauna and flora forests and of the arid, but rich, lands of the west", which will emerge especially during the administration of Theodor Roosevelt. Thanks to their work, for the first time the areas of most outstanding naturalistic value and the water reserves on which the prominent American cities depended (New York among them) became "reservations", protected by federal laws. Muir and Pinchot represent two contrasting approaches to the theme of conservation of natural resources. The environmentalist Muir prescribed the preservation of nature: the total protection from human influence. The conservationist Pinchot (conservation, which today we could define "sustainable development") recognised and interpreted unconventionally the cultural, political and social dimensions of the relationship between man and nature; he aimed at identifying tolerable levels of management of the resources for use.

Muir and Pinchot ecology and urbanism unagru architecture

Muir and Pinchot, when they were still friends.

Part 2

Where we encounter three of our heroes, Joseph Paxton, Frederick Law Olmsted and Charles Eliot, Who have introduced three crucial concepts of urban design.

The heroic phase of Landscape Architecture 1850-1900


In urban planning, and again in the US context, landscape designers experience, within a proto-ecological and romantic vision of nature, the integration between built and natural open spaces (Dumpelmann 2003). American landscape architecture inherits the teachings of the English and German landscape architects of the eighteenth century. It applies these teachings to the dynamic industrial world, where technological and economic development are profoundly transforming the natural landscape. Although it does not have an explicit statute or defined models, US landscape architecture is based on the idea that nature has healing properties, as argued by the founder of the discipline, Frederick Law Olmsted sr.. Olmsted introduced the idea of ​​"sanitation" to describe the relaxing effect of nature on human beings, particularly necessary in urban contexts. 19th century Landscape architecture was not an anti-urban or anti-capitalist movement but a professional activity that tried to equip itself over time and through design experiences with the tools required to design a functional and performative landscape. Olmsted identified these qualities with the English landscape: a picturesque aesthetic, mindful of the sequences of the scenarios, but at the same time based on the knowledge of local biological and hydrological processes. Capability Brown and Joseph Paxton (the Birkenhead Park in particular) were his main references. His was a proto-ecological approach that enhances the dynamism of fruition by constructing the landscape as a sequence of scenarios and uses theoretical models of ecology and forestry, such as succession and selective competition, to let natural processes select the plant species suitable for any context. In the American industrial cities, these principles are translated into new forms of integration of city and landscape, society and nature. Olmsted became the founder of the discipline when he (almost accidetally) won the competition for the design of New York's Central Park in 1858 together with Vaux. In their proposal, the park is not a natural element isolated in the mineral fabric of the dense city, but a man-made landscape, manipulated through earth movements, excavations and natural selection of plant elements, perfectly integrated in the fabric of the city. Olmsted and Vaux's design was in fact the only that solved the issue of keeping some form of connection between the two sides of the park, which would have otherwise a seprating element. Through a system of connections at different levels the design allowed the coexistence of pedestrians, horses, carriages and animals. The Park is an infrastructure that fits into the continuity of the urban fabric without interrupting its connections; on the contrary, it enhances their complexity. The multifunctionaityl of the design solution - park, infrastructure - signals the intent to integrate city and nature: finding an innovative "form" of hybrid urban natural development, in line with the needs of the expanding metropolis.

new york central park ecology and urbanism unagru architecture
archway london ecology and urbanism unagru architecture

The Park System

The model of the urban park evolved into the park system: a system of interconnected open spaces that were prefigured in areas not yet reached by urban expansion; an idea that spread to major American cities, starting with the Minnesota system, designed by Horace Cleveland. The park system is a concept, rather than a fixed physical solution: on the one hand it prescribes continuity and connections between green spaces (in this sense it anticipates systems theory, interscalarity and ecological networks); on the other, it shuns rigid schemes. An important innovation of this model is the Boston Metropolitan Park System, conceived by Charles Eliot jr. (a student and later a business partner of Olmsted), The first regional plan for the protection and implementation of natural resources in relation to urban growth. Developed when the city was already among the largest in the United States, the value of the land high, few open spaces, the plan proposed to acquire the residual areas, often degraded and compromised by pedological or hydrological problems, to create punctual and linear system of open spaces for the city. A retroactive intervention strategy that sought to insert itself into the speculative development mechanisms of the American industrial city.

boston metropolitan ecology and urbanism unagru architecture

The Emerald Necklace and the Back Bay Fens

The project of the Emerald Necklace, designed by Frederic Law Olmsted between 1878 and 1890 (Zaitzvesky 1992), is a filament of open spaces that connects the city with the large Franklin Park on the outskirts by configuring an ecological corridor. It highlights the contractual and conflictual dimensions of the land acquisition process: linear and punctual elements of variable size and width through the marginal areas of the city. Olmsted designs the different components of the linear system by integrating hydraulic control devices, connections through parkways, and landscape design. The Back Bay fens (marshes) constituted the last ring of the system, which followed the course of the Muddy River and accompanied it until it entered the Charles River, whose flow was influenced by the ocean tides. The vast wet area of ​​the fens had been progressively reclaimed to make room for urban expansion, causing the disappearance of a landscape and a system of ecological functions of hydraulic regulation and water purification. In the second half of the century the expansion had occurred rapidly and had affected various areas of the Charles basin, where the sewage was discharged; the morphology of the soils and the intermittent trend of the tides caused the accumulation of effluents in the fens. The hydraulic engineer corp had proposed a masonry lock to control the oscillations of the tide. Olmsted instead proposed to tackle the problem of "sanitary improvement of the Back Bay drainage basins" by building sewer infrastructures that divert the flow of wastewater and the Muddy River from the Fens. The move allowed the latter to return its original wet area condition. And yet the system is an eminently artificial one: the connection with the Charles River and the ocean tides is regulated by a weir, which limits the oscillations of the hydraulic level (Krinke 2001). The integration of the "common" landscape into the urban fabric occurs once again through the overlapping of flows: the parkways and promenades that develop along the Emerald Necklace are designed as connecting systems between the two fronts of the linear park. The Necklace is, therefore, at the same time, an ecological corridor and a system of urban crossing and connections. The Fens are structured as a superposition of three layers: an underground skeleton of sewer infrastructures, the modelling of the soil functional to the "natural" wet landscape, the system of urban connections, three layers that make up an urban infrastructure, governed by a lock.

park system ecology and urbanism unagru architecture

This concept can be paired with the landscape ecological corridor: a linear path connecting large patches of biodiverse landscape, allowing animals to move between patches and therefore increasing the resilience of the system: if something goes wrong animal populations can move to other patches.

park system ecology and urbanism unagru architecture
park system ecology and urbanism unagru architecture

The hybrid urbanisation

The park-infrastrucure, park-system and reclamation strategies point towards a new alliance between urban and natural, that is urgently needed in the context of the rapid rapid growth of the Western city, which came at the risk of completely obliterating vast ecosystems and condemning most of the urban dwellers to a life without nature.

The new hybrid urban-natural highway is the parkway: in Riverside, Illinois, the motorways are remodelled in shape and layout to gently adapt to the landscape, and are accompanied by deep areas reserved to forests: a very early version of ecological corridor, a more pleasant traveling experience, and a system to mitigate noise and pollution effects around the motorways. Landscape architecture, therefore, views the landscape as a perfromative and hybrid element of the human world; a programme and a conceptual model opposed to the neoclassical or baroque garden design, which aimed at the representation of monarchical power or humanistic principles.

The new urban settlement is the suburb, an idea and design typology taken from the English Garden Cities and first experimented in the 1920's Radburn, New Jersey. Soon after Frank Lloyd Wright will crystallise these ideals in the project of Broad Acre (later Usonia), possibly the most inspired anti-urban or hybrid-urban concept to be ever conceived and the topic of one of the next blog posts.

In conclusion, we have seen three important important concepts emerge from the work of early landscape architects, mostly based in the US.

The first is an open space strategy: a sequence of open (ideally public and green) spaces creates a system that can extend to become a network.


The second is the idea of urban regeneration through the coordinated trasnformation of brownfield sites. This processual idea vastly expands the potential for transformation of several territories, while introducing time into the equation of urban transformations: sites are often bought or taken at different moments and will always require different degrees of reclamation or preparation.


The third, only hinted in this post, (I will return to it in more detail) is the idea of stepping stones, where several points form an invisibile continuity just by their proximity.

Part 3

Where we meet the absolute hero-est of them all, Ian McHarg.

ian mcharg ecology and urbanism unagru architecture

Ian McHarg virtually created the discipline of environmental planning. His work is part of research for an alternative cultural approach to the dominant dichotomy of economic development vs equality and nature. First, Patrick Geddes and then his pupil Lewis Mumford had pursued a "third way" for urban development: "the city as a polis in harmonious relationship to the organic complexity of the regional ecosystem" (Steiner 1997, 57). The historical relationship between morphology, ecology and the social production of space, which Geddes exemplified with the phrase work, folk, place, and which Mumford had described in his historical evolutions in "The Culture of the city" (Mumford), are translated with a particular emphasis on environmental dynamics in McHarg's work.

patrick geddes ecology and urbanism unagru architecture

Patrick Geddes's Valley section. Worth an entire new post.

ian mcharg ecology and urbanism unagru architecture

An evolution of the valley section, Ian McHarg's section of a residential settlement proposal.

After World War II, Ian McHarg elaborates a theory of ecological planning, reusing and systematising the different traditions of American landscape architecture and inheriting the research program of regional planning and social ecology from his mentor Lewis Mumford. McHarg embodies the combination of two almost opposite approaches to the relationship between society and nature: he is an ecologist, an activist who takes it upon himself to disseminate ecological knowledge through radio and television broadcasts; and a landscape planner and designer, attentive to the relationships between urban space, quality of life, economic development. The condition of the human being in the modern city, in continuity with the idea of ​​sanitation, is described in terms of disease, which McHarg defines as the inability of the urban habitat to adapt to the physiological needs of the inhabitants. McHarg's theoretical contribution is based on pragmatic considerations of the usefulness and effectiveness of an interdisciplinary knowledge that allows to verify the results of transformations, as opposed to the irrationality of choices guided by the exclusive speculative interest: a critique that extends to the ordering of daily life, to individual consciences and to cultural and religious debate. In designing with nature (1967), McHarg elaborates a complex theory on the relationship between man and the environment through the development of ecological concepts that are declined in a socio-spatial and philosophical sense at the same time. One of the thought experiments in the volume describes an imaginary space capsule that should have brought a man to the moon using the least possible amount of resources: sunlight, water, bacteria, and algae. The capsule is a limited ecosystem, where oxygen, nutrients and waste must be continuously reused and renewed to allow the astronaut to survive.

Reporting in spatial terms the evolutionary theories of succession and flows of matter and energy, McHarg describes two possible forms of evolution of ecosystems: the entropic or destructive one, through which the energy introduced into the system progressively degrades as the disorder increases; the creative or negentropic one, in which the energy supplied is transformed into increasingly complex and varied systems, therefore more and more ordered and in dynamic equilibrium. This last type of evolution characterises ecological systems: "Energy is temporarily trapped; it will inevitably be dispersed in entropy, but it will also be replaced. Meanwhile, living creatures […] cause matter to rise to higher orders" through the work of plants, first, of other organisms later."

Planning as a form of evaluation

staten island ecology and urbanism unagru architecture

McHarg's devised a method to understand the how the landscape works, how it has affected and can affect societies and cities, and how to design new development. The method uses overlay mapping: superposition of maps describing different aspects of the landscape to extrapolate new information. The succession of layers is chronologically ordered: geologists and climatologists identify the longer-term processes that had defined the geomorphological structure; hydrologists describe the surface and groundwater cycles that feed biological life, represented by landscape ecologists and botanists; finally, historians, sociologists and urban planners have at their disposal the tools to understand the characteristics of each site and the conditioning they had exercised on settlement dynamics. Combining the data, McHarg was able to recognise the hidden differences in the landscape and identify the suitability for development of each area. McHarg called this method ecological determinism. Only after investigating the full scope of the natural-social relationships can the ecological designer start her creative work.

Ecological determinism goes both ways: on the one hand it allows to suggest how we should intervene in the territory; on the other, it highlights the historical links between nature, social evolutions and the social processes of production of space. Like never before, the agency of nature is made evident: performing functions of protection, nutrition, sustenance and ecological balance on which cities depend. With the increase in the possibilities of movement and choice of settlement environments, according to McHarg, even human ecologies tend to become more and more specialised: man adapts in different forms: "man-nature" is different in every place, "There is the morphology of man-Piedmont, man-Coastal Plain [...]" and so on.

Staten Island, maps and overlays.

The Valleys

The plan for the Valleys, an area under development north of Baltimore, is a classic example of applying this design process. The brief involved the construction of a typical American suburb: economical and efficient design of the infrastructural network, private gardens, and urban sprawl. Based on geological, hydrological, ecological investigations and overlays, McHarg classifies the landscapes of the area according to their availability for urbanisation: the result is an organic diagram that highlights above all the piedmont areas, more stable and less fertile, but which widens, with less intense gradations, even on some scenic slopes. The design proceeds through the definition of three transformation scenarios: the disordered one that had been foreseen maximises spatial dispersion and fragmentation; a second, linear one, concentrates the development along the existing transport arteries, thus saving the entire territory of the Valleys; finally, the proposed scenario is composed of different urban ecologies, laid out to minimise the impact of infrastructures and the built-up area, while taking advantage of the scenic and ecological services of the valleys. The difference in quantitative terms between the three schemes is zero; the difference in environmental, and creative terms is fundamental. The project suggested increasing the population density in the most suitable areas to preserve the most fragile ones. A diversity of settlement types allows to calibrate density and impact the land's conditions while allowing for the colonisation of almost all areas. The result is a complex settlement composed of some centres equipped with public spaces and collective buildings, vast suburban areas that occupy mainly the highlands, and more dispersed houses and services in the wooded areas.

the valleys ecology and urbanism unagru architecture

Bird's Eye view of the proposal for The Valleys.

After this long introduction, you might want to meet the man. Here's Ian McHarg:

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