A CITY IS NOT A FOREST: 
URBAN SUCCESSIONISM AND THE EVOLUTION OF CITIES

Taking the idea of Green Architecture to its logical conclusion – the city as an semi-autonomous ecosystem – gives us another way to think about urbanism. But how does an urban ecosystem function? How does it come into being, grow, evolve?

SUCCESSIONISM IN FORESTS

An ecosystem just doesn’t emerge fully formed overnight. In a forest, for example there is a distinct process that occurs, something known as the succession pathway: First, nudation, which could occur, say, after a glacier has exposed a raw granite in a canyon such as in Yosemite. Next is the migration and arrival of propagates, then rooting and initial growth, then competition of species, which, for a given set of conditions leads to a climax community, a mix of species that achieves a fairly stable equilibrium. Such an equilibrium usually remains in place until the conditions change, either slowly or due to trauma. When the change is slow, the equilibrium shifts to adapt; when the change is sudden and/or catastrophic as in a fire or ice age, a sort of nudation occurs and the cycle begins anew with a succession of plants more suited to the altered condition.

SUCCESSIONISM IN CITIES

In cities, the succession pathway would also occur, in an albeit modified way: nudation would describe the raw land prior to the arrival of humans; the migration and arrival of propagates would refer to the first settlers, who would accomplish rooting and initial growth of the city by erecting non-native buildings according to their own traditions. Competition of building species would begin upon arrival of subsequent settlers who would erect their own non-native buildings as needed; a succession of species would take turns being dominant; this pattern would continue through waves of growth until reaching, for a given set of conditions, a fairly stable equilibrium consisting of mix of species with one or more achieving dominance. As with forests, such an equilibrium would remain in place until the conditions change, either slowly or due to trauma. When the change is slow, the equilibrium shifts to adapt; when the change is sudden and catastrophic as in a fire, earthquake, or economic crisis, a sort of nudation occurs and the cycle begins anew with a succession of species more suited to the new conditions.

EVOLUTION IN FORESTS

A forest has a variety of ways it can adapt to changing conditions. Successionism favors contingency over climax, meaning that a climax community is most often transitory, that a state of constant adaptation is more the norm, as environmental conditions continually shift. Evolution occurs at the level of the individual and at the level of species, where, through natural selection, good traits persist across generations and where innovations introduced by new variants are also rewarded. Desire to thrive propels individuals and species to adapt or die. New species are formed once this adaptation passes a certain threshold. And when it comes to the survival of the forest itself, there is an additional tool: the ability of the ecosystem itself to mutate to create the optimum mix of species for the forest to endure.

EVOLUTION IN CITIES

Cities are like forests in that adaptation to changing conditions is driven by a desire to thrive: most development occurs out of an attempt to meet a present need. The city also has many tools it can use to adapt. Building owners can alter individual structures to meet their needs; or they can build a new mutation of an existing species, one with adjustments that more closely match what they want; or they can develop an entirely new species.

Cities are not like forests in that conscious human intervention often directs the process. The evolution of cities is moderated by pressures not present in forests, social forces looking both forward and backward: Planning, a force driven by a hope of what city might become, tries to anticipate and shape future development, while Preservation, a force driven by the memory of what once was, attempts to protect the city from further change. In most cities both these forces work in various degrees to temper the mechanics of what a pure Darwinian capitalism might wreak, often simultaneously encouraging and discouraging new species from taking root.

URBAN ECOSYSTEMS

For cities, the establishment of propagates, successive dominations, fugitive equilibria, traumas, and rebirths occur over and over again with a climax state remaining ever elusive. This is because unlike forests whose ecosystems are driven by Ecology – which is always seeking equilibrium – the ecosystems of cities are driven by Economy, which is always seeking expansion. For a city to survive it must continue to grow. This requires a climate conducive to growth, when both a robust economy and the political will converge. This means growth occurs during times of economic expansion, often after trauma – Fires, Floods, Earthquakes, War, Depressions, Recessions, etc. – mobilizes a city to rebuild itself. In fact, Post-Traumatic Stress is a fertile time for cities, when more new species are created and established; but propagation relies on economic expansion to make it possible.

URBAN SUCCESSIONISM IN LOS ANGELES

Could this be why cities look the way they do? Because they reflect the styles in vogue during times of greatest economic expansion – why Paris is so dominated by Hausmann era apartment blocks or San Francisco is so Victorian? Or why the Inland Empire looks the way it does? Clearly there are other factors involved; but looking at successive dominant species does make cities more legible. Los Angeles, which at first glance appears quite incomprehensible, seems to undergo a major shift every 30 years; tying its architecture to its economic cycles helps to bring the city into focus.

Pre-1885

In the beginning, the first settlers – the Tongva – seem to have built no permanent structures in the village of Yangna near downtown. Instead they famously gathered around what was later termed El Alisal, a massive Sycamore located on a spit of land now sandwiched between on and off ramps for the southbound 101. During the Spanish and Mexican periods, the architecture was Spanish Colonial. Later, as the economy shifted from the missions to cattle ranching, the architecture remained simple, mostly adobe structures.

1885-1915

When the railroad reached Los Angeles, the first real estate boom hit the city and the new buildings reflected this, reshaping what had been a sleepy Spanish-speaking outpost into a growing Victorian metropolis. As more and more people flocked to Southern California for the healing effects of its weather, people like the Greene brothers adapted the forward-thinking yet non-native Arts & Crafts movement to create a new California variant that propagated, mostly as bungalows, across Southern California through the first World War.

1915-1945

The rise of the oil economy, increased car use, and the birth of Hollywood further accelerated the growth of the city. The dominant species between the wars were the adapted non-native period work of architects such as Wallace Neff, Gordon Kaufmann, and Paul Williams in the private realm, while the public realm favored the art deco style found in ferro-concrete infrastructure throughout the city.

1945-1975

Coming out of World War II, a new real-estate boom, propelled by the surging aerospace industry, swelled the city and a fascination for the future fueled an explosion of new building species. Following the earlier adapted non-native strains of Modernism from Frank Lloyd Wright, Rudolph Schindler, and Richard Neutra, new home-grown hybrids were developed by efforts such as the Case Study program and propagated by a housing industry hungry for new product.

It was also during this period that the most significant transformation of Los Angeles took place in the many ways it adapted to the ongoing trauma caused by that most invasive of pests – the car. Not only did these adaptations change the way the city looked, but the auto itself changed the way we lived, steadily diminishing the public realm while expanding private one. Though the process began when the car was first introduced, it was during the post-war period that the most massive concession – the system of freeways that first disrupted then later defined the city, was constructed.

The car induced trauma indirectly as well. Allowing freedom of movement throughout the city, the car eliminated the need for intra-urban rail, which had created a matrix of villages across the city. It incentivized real estate developers to fill in between the villages, which erased boundaries and made inevitable the annexation of those villages into a single, massive urban ecosystem.

1975-2005

Following the malaise of the post-Vietnam era, the new species that emerged were mostly a postmodern mess. The era that spanned approximately from1975 to 2005 produced such unprecedented hybrid species as the McMansion, the minimall, and the Alameda Corridor; however it also witnessed the birth of more compelling hybrid species from Frank Gehry, Eric Owen Moss, and Morphosis.

2005-Beyond

Based on our past, it appears we alternate every thirty years from a forward to a backward-looking trend in species making. Where does that put us today? Even though we see the unfortunate propagation of apartment mega-complexes like the Medici and the Orsini – invasive non-natives, adapted, it seems from similar such apartment communities in Orange County – I have the hope that a new green economy will pull us, through technological innovation and force of will, toward embracing the future once again.

CITIES AS ECOSYSTEMS

In order to allow ourselves to view cities as ecosystems, we actually have to shift they way we think about our role in the world – not as separate from nature, but as part of it. The question is, how to balance Ecology and Economy to reach an equilibrium in which both are sustainable? We need to think holistically about villages, cities, and regions that function somewhat self-sufficiently on their own, yet operate more significantly as linked elements in ever larger ecosystems.

Studying cities as ecosystems places architecture in a context that is larger than traditional histories of architecture seem to consider. While this appears to remove architects from a central role in the shaping of cities, it actually frees us up. Like mad scientists working in remote labs concocting cures for unimaginable diseases, architects are at the forefront of imagining new species to adapt to present and future conditions. If you want to get excited about the future, just walk through an advanced studio in any one of the several architecture schools in Southern California. We may not have an economy to build these emerging visions just yet, but when we do, we’ll have plenty of interesting options.