The Invisible in the City

Much that happens in cities -- urban areas more broadly -- is not obvious to the naked eye or to casual observation.  The invisible things in urban social-ecological systems represent four key dimensions: social processes and their legacies; the built and technological structures and infrastructures; ecological structures and processes; and influences and events that arrive from a distance.  These ordinarily invisible features of urban systems can become visible when something goes awry, or when some long-forgotten decision rears its head as a legacy shaping current conditions or options.  The invisible becomes visible when something "breaks" or is unexplainable based only on current or local conditions.

 

Social Invisibility

Social legacies take myriad forms.  This blog has presented several examples, from the clashing street grids in Baltimore arising from orientation to different shorelines around a complex harbor, to the mortgage redlining that mirrors the concentrated abandonment in city neighborhoods. 

The "break" of the clashing grids is revealed in several layers of attempts to knit the city's traffic flow more seamlessly.  The disjunction between the north-south grid of the Mount Vernon neighborhood and the north-west to southeast orientation of the Madison neighborhood reflect differences between the orthogonal north-south/east-west orientation of the monument-studded downtown grid, and the more organic flow following the old market road on the high ground of the divide between the Gwynns Falls and Jones Falls watersheds, which trends northwestward.  

The 1890 map of Baltimore City, showing the multiple, incongruent street grids.

The break of redlining is actually part of a longer-term and persistent system of racial, ethnic, and class segregation that has characterized Baltimore since at least the demise of post-Civil War Reconstruction and the rise of Jim Crow laws, customs, and conventions.  Given that the primary source of wealth of most Americans is investment in a house, the denial of mortgage security put the residents of neighborhoods judged by the federal Home Owners Loan Corporation to be less than mortgage worthy at a significant and lasting disadvantage in the accumulation of wealth.  Other local ripples of this situation extend to property tax revenue flow, educational resources, and through a complex cascade to access to such things as gainful employment in a post-industrial economy and grocers purveying fresh vegetables.

The 1930s redlining map of Baltimore city, with green, yellow, and red overlays indicating high, medium, and low mortgage desirability based on factors such as race, national origin, and housing stock.

Infrastructural Invisibility

Much built infrastructure is literally out of sight.  Fresh water and gas mains are buried beneath streets and sidewalks, as are sanitary sewers and storm drains.  The drainage infrastructure exemplifies the complexity of build infrastructure.  In row house neighborhoods in old Baltimore, the stormwater drainage system extends from roofs sloping from the street sides of houses toward the back yards, with downspouts draining into alley gutters, which conveyed water to storm drain catch basins in the streets.  So the infrastructure was not just the pipes, but also the roofs, downspouts, gutters, and then the buried drain pipes.  Many of the underground stormwater pipes were, in actuality, buried and piped streams.  The breakage of this stormwater system is seen in the collapse of roofs of long abandoned houses, and the puddling of rainwater in cellar holes and elsewhere where debris collects or obstructs the flow of rain water. 

Water main break at Gay and Lombard Streets.

Other forms of breakage are the common leaks that unintentionally connect the remaining surface streams, the sanitary sewers, and the storm drains.  The pressurized drinking water system also leaks, adding flow to streams and the two sewer systems, and in some cases adding an avoidable burden to sanitary treatment facilities.  

 

Invisible Ecology

Perhaps the least visible component of urban systems is the ecological structures and processes they contain.  Of course, the large green spaces in cities, suburbia, and exurbs are obvious.  Signature parks, golf courses, cemeteries, and the green campuses of private and public institutions are often recognized as ecosystems, a designation that clearly acknowledges their ecological content, and facilitates their inclusion in designs and plans.  However, such large and often socially valued properties are not the only venues for biophysical processes in urban systems.  Yards, volunteer vegetation along fencelines, slivers of lightly managed areas along rights-of-way also contribute to the ecological processes.  Hidden riparian strips behind shopping malls, or at the backs of factories, or transportation corridors can also be seen as ecosystems.  Clearly, there are many ecological processes that occur in these sites: nutrients are cycling, carbon is being processed, decomposition of organic matter is under way. 

However, these quintessential ecological processes are also occurring in urban soils, in surface streams, and in largely ignored wetlands.  Biodiversity -- native and introduced birds, medium sized mammals, and an impressive complement of microbes -- are active throughout the urban system.  Some of these help retain potentially polluting nutrient compounds, sequester some of the climate-changing carbon that economic processes release, help control disease agents, or simply give pleasure to urban residents.  Some of these organisms release contaminating byproducts, and others are themselves disease agents or vectors.  But together they constitute a web of interactions and influences that generate amenities and hazards in urban areas.  Harnessing the positive outputs of urban biota, conserving native biodiversity, and limiting the risks that some organisms pose, requires making them and their interactions visible features of the city.

 

Invisible from a Distance or from the Past

Not all things that influence the social-ecological structure and processes in a given urban area constantly reside or originate within it.  This is especially true of socially-generated influences, which arrive in the form of new migrants at airports, appear as redistribution of financial capital via investment, disinvestment, or personal remittance, or exist as cultural products such as fashion, movies, or music.  Political movements can be seeded from a distance, and opportunities for trade, migration, or commuting determine population densities, economic activities, or cultural vitality.  Social influences, either personified or electronically mediated, are extraordinarily mobile in the globalized, urban world.

A tornado over Baltimore in June 2013

Other, seemingly more concrete effects also arise from outside a given urban area.  Biophysical agents of disturbance, those events that can disrupt the physical structure of a city, often arrive from elsewhere.  Hurricanes, with strong winds, coastal flooding, or torrential inland rains are a familiar example.  So to are storm fronts that unleash snow, ice, or tornados.  Climate change, with the potentials for obvious change in average temperatures, seasonal distributions of heat, cold, wet, and dry, is a prime and increasingly widely appreciated action from outside.  Ironically, the high energy demands of urban systems contribute to these global changes, which come back to haunt, in some form or another, virtually every urban area on the planet.  Notably, many of the changes associated with climate change are already well developed in urban areas.  Heat islands, heat stress, drought, and extreme storm events are phenomena that urban policy makers, managers, and citizens are planning for and adapting to at present.

 

The Invisible as Personal

Given that humans seem to give greatest credence to events and things that they have themselves experienced, it may be that a great deal of what characterizes urban social-ecological-technical systems remains invisible.  The experience of individual persons, or even a nuclear family, is constrained.  Human memory is powerful and poignant, but it is temporally quite limited.

On the scale of a human life span, or the span of two or three generations' memory, many important ecological events can be missed.  Fires in uninhabited chaparral -- shrubland in the mediterranean climates of the American west -- may recur about once every 70 years on average.  A single generation, or even two, may not have seen a big chaparral fire.  Chaparral vegetation is made up of species that are adapted to reproduce after fire.  Indeed, without fire for long periods, other species can replace the chaparral dominants.  Add short human life spans to the fact that the majority of residents in American mediterranean climates are likely to be new arrivals who lack a personal access to multi-generational memory, and the possibility of chaparral fires to be invisible parts of suburbs and exurbs in California or Colorado is enhanced.  Many vegetation types are affected naturally by fire, such as many pine forests in the south and eastern U.S.  Others are affected by periodic catastrophic wind storms, albeit on a time interval of several centuries.  Extreme floods also periodically affect many riverine areas.  However, if people have never experienced such a flood, or if they are lulled into security by a floodwall built to contain the last most catastrophic flood plus a foot or two, the risk is essentially invisible.  In such situations, floods "to worry about" are virtually invisible.

This is a common phenomenon.  Reporting on urban disasters driven by otherwise invisible ecological events often includes this kind of sentiment: "I've lived here all my life, and I have never seen anything like this before."  The "this" can be a wind storm, blizzard, hurricane, huge tornado, or outbreak of some native insect.  Add to this list new invasive pest or disease organisms, intensifying storms due to climate change, shifting and deepening of drought prone pockets, and so on, and the list of the invisible in the city becomes longer still.

The invisible in the city points toward the need for humility -- individual memory often misses rare weather events, social legacies no longer much spoken about, or catastrophic infrastructure failures of the past.  Even family or communal memory seems fallible.  The invisible is a key part of cities and urban systems.  Urban social-ecological-technical research helps to lift the veil.  Maybe the old New Englander suggests how to operationalize humility in the face of the invisible: The question was asked, "Have you lived here all your life?" The droll reply was, "Not yet."  One hopes the answer suggests an openness to the invisible in that lived place.  Seeking the invisible in the city is one of urban ecology's primary tasks.

The Human Ecosystem: What's Missing?

The human ecosystem concept is one of the most common tools used in the Baltimore Ecosystem Study LTER.  Adopted from a team of social ecologists and sociologists who were involved in community forestry in the Himalayas, the application of such approaches to underserved areas in American cities, and the conservation and management of US National Parks, the concept is remarkably broad and adaptive.  The human ecosystem is not necessarily tuned to emphasizing the intellectual flavor of the week or most current headline issue for cities, urbanization, sustainability, or development.  However, its inclusiveness, nested hierarchical nature, and adaptability makes it well suited to dealing with shifting or even new emphases in social-ecological systems research and application (Figure 1). 

Figure 1.  The Human Ecosystem Framework
(Adapted from Machlis et al. 1997)

What are some of the hot topics that might seem to be missed in our discussions or presentations, but which in fact have a home in the human ecosystem framework?

Political ecology.  

This is at once a scholarly area and a subject of activist attention.  As a scholarly field, it examines the relationships of politics, economics, and environment.  As a social movement, it focuses on the inequitable distribution of benefits and costs of environmental decisions.  The social movement can be seen as a part of a larger social or environmental justice agenda. 

The multidimensional relationships with which political economy is concerned exercise several components of the human ecosystem framework.  Among the bioecological features, catalogued in the “ecosystems pattern and process foundations” component of the framework, many are relevant, including the distribution of energy, water, nutrient, and biomass resources, the kinds and levels of contaminants and pollution of air, water, and soil, and the heterogeneous or mosaic distribution of all of these factors.  Heterogeneity is important because control of access to resources, exposure to hazards, or distribution of benefits is subject to social – that is power and political – control.  Not all persons, groups, or institutions may be uniformly represented across a spatial mosaic.  The social control of access, exposure, and benefit engages many of the components of the human ecosystem framework.  The social ordering by factors of identity, rank hierarchies, and norms are key to the differential power relationships in human ecosystems.  Social rank hierarchy can further be broken down into ranks based on wealth, control of territory, social status, knowledge as a kind of capital, and, tellingly, power.  Among the social and cultural foundations, the distribution of populations, including by race, class, gender, or ethnicity, and the distribution of information by various institutions may reflect power relationships.  Of course the access to or participation in the institutions of sustenance, health, justice, education, etc. are also dependent on power relationships.  Other aspects of the human ecosystem framework (Figure 1) can also be used to investigate and explain, and therefore intervene in, power relationships in the urban social-ecological systems. 

Technology.  

Recently, our colleague N.B. Grimm has emphasized the fact that social-ecological systems have significant technological content.  Grimm at the 2013 Congress of Urban Ecology, the first such international meeting of the Society of Urban Ecology (SURE), introduced the term Social-Ecological Technical System, or SETS to emphasize the role of technology in how people think about urban ecosystems. 

This healthy reminder and highlight does no violence to the human ecosystem framework.  A classical representation of the significance of technology in human environment relationships is the POET model.  Under this general model, environmental change is said to be a function of human population, the way that humans are organized, and the technology available.  Explicit recognition of the role of technology in urban systems appears in the classical work of Borchert (1967), who notes that urban form in the United States shifted with the introduction of new technologies.  

Emphasizing transportation technology, Borchert proposed five epochs of American urban change: 1) sail and wagon (1790-1830), 2) steam powered ships and initial rail roads (1830-1870), 3) national steam rail network (1870-1920), 4) interstates and propeller air transport, and finally 5) satellites and jet propulsion.  American urban transformation continues, with other epochs hypothesized to represent the “slow growth” proposed in the 1970s of the oil embargo (Phillips and Brun 1978), or perhaps an epoch defined by the technology integrating global finance, manufacturing, and consumption.  In any event, the significance of technological innovation, change, and even retrenchment are clearly major components and drivers of urban change.  These latter technologies have a great deal to do with the current global teleconnections of urban systems with each other and with more rural and wild lands (Boone et al 2014).

Baltimore is a prime example of the role of shifting technologies.  For instance, the urban fabric of Baltimore, as described in Hayward and Belfoure (1999), shifted markedly with each transition -- from the walking city, through the city of horsedrawn trolleys, through the electric commuter rail, through the automobile era.  The industrial power of Baltimore similarly reflects major technological shifts, from the water power of the “fall line” through wood fueled steam, through coal powered manufacturing and steel production.  Other overlapping shifts, such as the opening up of the American South and Southwest with the availability of air conditioning technology there, and government policy for the location of defense industries away from the vulnerability of the east coast so feared during World War II, played a role in Baltimore’s post-industrial shift to a joint service, tourism, and knowledge footing.

In the Human Ecosystem Framework, technology appears foundationally in such things as the source of energy (e.g. water power, vs. wood, vs. coal), or the path of water flow (the location at the fall line between the Piedmont and the Coastal Plain).  Technology also is reflected in the amassing and deployment of labor, as in the contrast between slavery and voluntary immigration as sources, and the shift in capital investment in water-mill industry and canals versus the creation of America’s first long haul railroad – the Baltimore and Ohio.  

The technologies available and the pursuits different technologies make available have powerful influence on social identity, demographic structure, community and neighborhood cohesion and the like.  For example Baltimore still embraces a historical identity as a seafaring town.  This is shown by the fact that a waterfront neighborhood is still referred to as Canton, in honor of Baltimore’s fast clipper ships that cemented trade between China and the U.S. East Coast.  Or the fact that Fells Point, the location of Baltimore’s first deep water port, still retains the ameities and reputation as a freewheeling entertainment district reflecting its early tradition of hosting sailors on leave.  The coal-fired industrial era is honored in the Middle Class Mythology of Baltimore and its blue collar ethos.  These things are all features that find a home in the human ecosystem framework, for example in cultural myths, social identity, and temporal cycles of change in demography and institutional and organizational structures.

Infrastructure.  

Another hot topic these days is infrastructure.  Strictly speaking, infrastructure is what undergirds the various components of a system.  Infra means below.  It is the supporting structure, linkages, flows in any system.  The human ecosystem may seem to be blind to the built and engineered components of urban ecosystems.  This is because the human ecosystem framework assumes those physical foundations.  In 1997, we worked to refine understanding of the bioecological foundations of the human ecosystem.  The original discussions by Machlis and colleagues certainly included the bioecological and biophysical aspects of human ecosystems in the “resource system” component.  Perhaps because buildings, streets, supply pipes, electrical wires, railroads, sewers, storm drains, and so on are such conspicuous parts of urban ecosystems, we hardly felt the need to call attention to them.  Cities are so often defined based on density of built structures and of human inhabitants that pointing toward buildings and infrastructure could be tacitly assumed.

However, a later description of the human ecosystem as a model template showing major kinds of components and their connections attempted to make this assumption clear.  Cadenasso et al. (2006) is a good example of this integration of built – and hence infrastructural – components into general interactive and classificatory models of urban ecosystems (Figure 2).  There is nothing wrong with pointing to the various components of systems as infrastructure, but in a sense, that seems redundant with saying that an urban place is a human ecosystem comprising social, biotic, built, and physical (e.g. soil, topography, climate) components.  Infrastructure is just another word for components, really.  The big idea is that cities, suburbs, and exurbs are systems that contain many specific features and connections, and that those span and connect biology, physical environment, buildings, social processes and the myriad feedbacks among components.

Figure 2. A process model template of the human ecosystem.

A healthy outcome of the infrastructure label may be helping people to remember the often invisible biological components of cities, suburbs, and towns.  Infrastructure is now often spoken of as gray, blue, and green.  This division suggests that the complex system of the city or more broadly, the urban region, depends on services and structures provided by plants, animals, and microbes, and that these services emerge not only from partly or (almost) entirely engineered features, but also from parks, yards, street plantings, derelict field and lots, open streams, wetlands, and freeflowing atmosphere.  Planning, design, management, policy, and education will be better served, and will better serve the human population when the contributions of biological infrastructures and their components are understood and effectively employed.

Conclusion

The message here is that the human ecosystem framework (Figure 1), a hierarchical enumeration of the kinds of biophysical and social structures, resources, processes, and outcomes that make up not only cities and towns, but also wilderness and production landscapes, is adequate to include contemporary and important concerns of power, justice, technology, and infrastructure.  The human ecosystem framework can be considered a causal hierarchy, in which general causes or factors are broken down into more specific mechanisms and interactions.  Specific models of human (in general) and urban (in particular) ecosystem structure, function, and dynamics will draw upon several to many of the ideas and features included in the human ecosystem framework. 

The framework is complemented by a process model template (Figure 2).  This process model template emphasizes that urban systems are composed of biological components and their interactions, physical environments and their links, social structures and interactions, and built components and the interactions among them.  This model template emphasizes the comprehensiveness of kinds of components of cities, suburbs, and exurbs, as well as the interactions among the various components.

Thus, rather than neglecting important contemporary topics in social, engineering, historical, and political realms, urban ecology has frameworks and model templates that in fact can easily accommodate these features.  Technology is a part of the built environment, Power is an aspect of the social structures, and infrastructure is a way to group various built components, networks, and interactions.

References

Boone, C. G., C. L. Redman, H. Blanco, D. Haase, J. Koch, S. Lwasa, H. Nagendra, S. Pauleit, S. T. A. Pickett, K. C. Seto, and M. Yokohari. 2014. Reconceptualizing land for sustainable urbanity. Pages 313–330 in K. C. Seto and A. Reenberg, editors. Rethinking urban land use in a global era. MIT Press, Cambridge.

Borchert, J. R. 1967. American metropolitan evolution. Geographical Review 57:301-332.

Cadenasso, M. L., S. T. A. Pickett, and J. M. Grove. 2006. Dimensions of ecosystem complexity: heterogeneity, connectivity, and history. Ecological Complexity 3:1-12.

Hayward, M. E. and C. Belfoure. 1999. The Baltimore rowhouse. Princeton Architectural Press, New York.

Machlis, G. E., J. E. Force, and W. R. Burch. 1997. The human ecosystem. 1. The human ecosystem as an organizing concept in ecosystem manageme

Phillips, P. D., and S. D. Brunn. 1978. Slow Growth: A New Epoch of American Metropolitan Evolution. Geographical Review 68:274–292.