Two Ways to Discover Disturbance

Ecological disturbance is often defined as an event that disrupts the structure of a specific system (Pickett & White, 1985).  This kind of material or physical disruption is important because it can result in changes in behavior of the system, or leave heterogeneous structural legacies that affect the system in the future (Pickett, Cadenasso, & Jones, 2000; Wiens, 2000).  Such a general and potentially significant ecological process requires conceptual clarity in order to use it successfully (Pickett, Kolasa, Armesto, & Collins, 1989).  As is often the case, seemingly simple definitions actually require great subtlety in their application.  Disturbance invites that kind of attention. 

This essay shows that disturbance can be recognized in two ways.  The first is based on empirical experience with events that have, in the past, commonly acted to disrupt structure of various systems.  This approach can be called event-based detection of disturbance.  The second approach allows disturbance as structural alteration to emerge from the comparison of different kinds of trajectories in a system.  Using such a lens, disturbance shows up as the intersection of long-term data about phenomena or processes with long-term data on system structure or function.  This second approach can be labeled emergent detection of disturbance.  This distinction may be important when disturbance is studied in systems where there is little prior empirical experience, or where interaction of events may be particularly complex.

Background: Disturbance as Process

Although disturbance is one of ecology's fundamental processes, the concept continues to be refined as more examples are brought to bear on understanding disturbance (Peters et al., 2011).  Disturbance can be conceived as a process, of which a conspicuous or powerful event is only a part.  

The process as a whole actually involves interaction between the forces embodied in the event and the characteristics of an ecological system that is exposed to the event.  The system characteristics govern how the forces can affect the system of interest.  In this sense, disturbance can be seen as a complex process because of the multiple interactions between an event and a place. 

The description above requires a caveat.  The term system can be used in different ways in reference to disturbance.  One arises because it may be reasonable to consider disturbance itself as a conceptual system of interacting components and phenomena.  "Disturbance as a system" refers to a conceptual model of the event, forces, and characteristics of places that may be affected by disturbance (Figure 1).  In contrast to a conceptual model involving disturbance, "the system of interest," uses the word system to refer to a concrete location, habitat, place, or ecosystem. 

Figure 1. Disturbance as a complex process (based on Peters et al. 2011 and Grimm et al. 2017)

Event-Based Detection of Disturbance

The refined conceptualization of disturbance, assumed here as background, suggests that there is more than one way to recognize or detect a disturbance.  The first is familiar, and rather intuitive when applied to scales comfortable to humans.  If we can travel through a system, and observe its dynamics at multiple points in time, it is usually easy to identify what a disturbance is.  Walking through a forest after a major wind storm may reveal newly fallen canopy trees, with their upturned roots, and the soil pit from which the roots were wrenched.  In that forest, some trees may have been snapped by wind, and saplings and immature trees may have been broken or bent as canopy trees fell on them.  The scene may be a complex jumble of altered forest structure from the canopy to the subsoil.  This is clearly a disturbance to the formerly intact forest ecosystem, and the motive force of wind equally clear as a driver.  Similarly, walking into a forest some time after a fire, whether one that "crowned" and burned the canopy, or one that was restricted to the litter layer on the ground, shows structural disruption of the prior forest structure.  New seedlings, surviving saplings released from competition with canopy trees, and understory herbaceous plants may respond by faster growth or enhanced reproduction following disturbance.  Such a human-scaled, intuitive recognition of disturbance events has led to familiar, if imprecise, statements that floods, fires, ice storms, landslides, hurricanes, and tornadoes "are disturbances" a priori.

The general model of disturbance (Figure 1) captures these intuitive cases that are linked to human size and experience quite well.  The model suggests though, that understanding exactly how the force of wind, the weight of ice, or the chemistry of combustion affected particular parts of an area require that the nature of the potentially impacted system or area to be known.  This requirement may be realized by rigorous and long-term observation of a system.  But generally, the focus on events matches the requirements of the general model well.  This use of the model is an example of the event-based approach to detecting disturbance.

Emergent Detection of Disturbance

Emergence is a contrasting approach to discovering disturbance.  Not everything that causes disturbance may be the result of a familiar or human-scaled kinds of event, like a hurricane or a flood.  In such cases, the disruption of system structure may result from the application of unexpected or non-intuitive forces.  Non-intuitive forces may exist on scales difficult for individual people to comprehend intuitively.  In addition, such unfamiliar drivers of disturbance may be especially characteristic of social-ecological systems.  The difficulty here is that powerful social-ecological drivers may seem ordinary and unexceptional to people in daily life.  Processes of real estate investment, employment opportunities, or government regulation may not seem at first glance to be the stuff of disturbance.  This invisibility of social-economic drivers is in part a result of the hybrid nature of such systems.  Hybridity or social-ecological-technological system structure means that the forces may have material and social momentum. 

What does such hybridity of forces mean in concrete terms?  If disturbance is an event that disrupts system structure, what counts as an effective event depends very much on what the model of the system is.  The requirement that an explicit model be used to determine what is and what is not a disturbance is an often neglected fundamental of disturbance studies.  Models of hybrid systems can express very different kinds of structures, all of which are important facets of the larger, more inclusive urban ecosystem.  The models state what components the system contains, and how the components of the system are networked together.  For example, social-ecological systems can have structures that serve to transfer information, or transmit social expectations.  Information may include the flows of capital or credit, and expectations may be transmitted in the form of such things as social norms or neighborhood cohesion. 

What can alter the such a socially inflected structure?  Of course, the physical disruption of communication infrastructure can be a disturbance.  This is very much like classical disturbance in ecology.  Alternatively, the physical networks may persist while the capacity of the social network to transfer information may break down due to the removal of an institutional node in the flow of information.  Or restriction of loans in specific areas may disrupt the financial resources that permits people to maintain and refurbish housing stock; ultimately this disruption of the financial system may appear as a material disruption in the urban fabric as buildings are abandoned and perhaps demolished. 

Examples of social features of structure can be labeled a "social contract," or an "ecology of prestige," each of which communicates expectations that influence how people interact in particular places.  A social contract in a African American neighborhood is a structure that can be disrupted by the novel, and perhaps conflicting, expectations about how public space is used and regulated that are put in place by gentrification.  The ecology of prestige is a place-specific social structure expressing a shared aesthetic that directly affects environmental form and management.

Figure 2. Illustration of emergence of disturbance as the intersection of a trajectory of lightning strkes and increasing density of wood stems.  Below a certain threshold density an ignition will not result in fire spread. Hence, there would be no disturbance of the larger landscape.

Disturbances of this kind are particularly complex, and may be more readily discovered by examining the trajectories of change in urban systems than by focusing on specific kinds of physical events (Figure 2).  Trajectories in important biophysical features of urban systems should of course be monitored, as should drivers from outside the system that can cause structural disruption.  However, the events that contribute to disturbance as a process can also arise within the system due to the interaction of changes in various system components. 

The fact that disturbance can arise in two ways in social-ecological-technological systems is a part of the complexity of urban ecology that has helped refine the understanding of one of ecology's basic phenomena.  The fact that the Long-Term Ecological Research program listed disturbance as one of the five core areas for research in its study sites is a symbol of the importance of disturbance across a range of system conceptions including populations, communities, landscapes, and ecosystems.  Disturbance can be hypothesized a priori in for some kinds of models, but must be detected analytically in others.

Steward Pickett

Literature Cited

Grimm, N. B., Pickett, S. T. A., Hale, R. L., & Cadenasso, M. L. (2017). Does the ecological concept of disturbance have utility in urban social-ecological-technological systems? Ecosystem Health and Sustainability, 3(1). doi:10.1002/ehs2.1255

Peters, D. P. C., Lugo, A. E., Chapin, F. S., III, Pickett, S. T. A., Duniway, M., Rocha, A. V., … Jones, J. (2011). Cross-system comparisons elucidate distrubance complexities and generalities. Ecosphere, 2, art 81. doi:10.1890/ES11-00115.1

Pickett, S. T. A., Cadenasso, M. L., & Jones, C. G. (2000). Generation of heterogeneity by organisms: creation, maintenance, and transformation. In M. L. Hutchings, E. A. John, & A. J. A. Stewart (Eds.), Ecological consequences of habitat heterogeneity. Malden, MA: Blackwell.

Pickett, S. T. A., Kolasa, J., Armesto, J. J., & Collins, S. L. (1989). The Ecological Concept of Disturbance and Its Expression at Various Hierarchical Levels. Oikos, 54(2), 129–136. doi:10.2307/3565258

Pickett, S. T. A., & White, P. S. (Eds.). (1985). The Ecology of Natural Disturbance and Patch Dynamics. Orlando: Academic Press.

Wiens, J. (2000). Ecological heterogeneity: an ontogeny of concepts and approaches. In M. J. Hutchins & A. J. A. Stewart (Eds.), The ecological consequences of environmental heterogeneity. Malden, MA: Blackwell.

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 Science of Connection in a Disconnected Place

The news from Baltimore has been sad and disturbing over the past few weeks.  Urban ecologists, like all ecologists, I think, love the places where they work.  So I must remark on what is happening in Baltimore and what it means to me, as a scientist who has committed more than two decades to research on the ecology of metropolitan Baltimore. 

But this post is not the usual kind of thing for this web log, which typically intends to note conceptual issues for the BES community, or provide alerts and background for important project activities, or stimulate interactions of BES with other projects conducting urban ecology research, education and community engagement.  This post is more like an editorial, in which I explore my own reactions as a scientist and as an African American to the troubling recent events in Baltimore.  Like the playwright Eugene Ionesco, I write here “to find out what I think.”  These opinions are my own and do not reflect those of other researchers, educators, or funders of BES.  Here goes.

The Science of Connection

Ecology can be thought of as a science of connections.  In fact connections, in the form of interactions, are enshrined in the early definition of the science: The study of interactions between organisms and their environment.  A more fleshed out version expands this, but keeps interaction and processes as key: The scientific study of the processes influencing the distribution and abundance of organisms, the interactions among organisms, and the interactions between organisms and the transformation and flux of energy and matter. 

This fundamental interest is sometimes trivially reduced to the idea that everything is connected to everything else.  But what makes the ecological world work is not that everything is connected, but that things – organisms, processes, places – are differentially connected.  That is, some connections are strong, others are weak, and some don’t exist.  Some connections are brief, some persistent, and some change strength over time.   Some connections happen through close contact while others are transmitted by signals, materials, or cascades of effects over great distances. 

It is the job of ecological science to understand the nature and effect of such differential connectivity and exchanges in the systems it studies.  The connectivity principles of ecology might be better summarized like this: 1) everything is connected to something else; 2) connections change over space; 3) connections change over time including being created anew and disappearing; 4) connections are the glue in ecosystems, linking organisms, biological processes, and physical structures.  In urban ecosystems, social structures and processes, and infrastructures are included as nodes of connection.

Baltimore as a Differentially Connected Mosaic

Baltimore, including the chartered city and several nearby counties of equivalent jurisdictional level, is a hugely heterogeneous, patchy ecosystem.  The patchiness reflects the underlying geology and soils, the vegetation types, and the contrasts between wet and dry places.  It reflects where buildings and infrastructure have been installed, and where they have been replaced or abandoned.  It reflects the things that people plant for agriculture or for decoration, as well as plants that disperse, establish, and grow spontaneously.  It reflects how and where all these plants are managed – or not.  Patchiness reflects the habitats that people intentionally or accidentally make for animals, and the fact that people move animals around.  It reflects where people choose to settle and live, and where firms locate or leave from, and where people with different resources and social characteristics have access.  It reflects policy that govern zoning, transportation, financial investment, taxation, and public versus private expenditure. 

Many more sources of spatial differentiation could be mentioned.  But key is the idea that such patchiness sets up a field of differentials for connectedness in the Baltimore region and in its subsystems.  Like all American urban regions, Baltimore’s heterogeneity appears in the form of contrasting neighborhoods, social relations, wealth, and ecology.  BES has spent 18 years applying interdisciplinary methods to understand how this complex, differentially connected system works.

Disconnection in Baltimore

The sad fact and circumstances of the death of Mr. Freddie Gray point to some of the deep and persistent disconnections that exist in parts of Baltimore.  Certainly, the kinds of disconnection in evidence here are shared with many American urban systems – old and new, majority African American or not.  And certainly, not all neighborhoods in Baltimore are disconnected.

Sandtown,the neighborhood where Mr. Gray was born and in which he apparently suffered the wounds that led to his death a week later, is one in which we work.  It is a part of Watershed 263, a watershed defined by a stormwater drainage catchment.  Mr. Gray’s Sandtown is at the northern headwaters of this drainage catchment.  We use the drainage network – the watershed – as a tool to study connections between built infrastructure, household and institutional decision making, community activities aimed at environmental quality, and the amount and quality of the water draining different parts of the larger Watershed 263.  We use the same concept of watershed throughout the Baltimore region to understand how the rich diversity of patch types and their social, built, and biological conditions affect the water quality and flow across the entire Baltimore region.

Social Disconnection

While our watershed ecology research uses a conceptual tool emphasizing connection via water, it has become clear that Sandtown is a place of profound social disconnection.  There are many people within Sandtown and the 10 other neighborhoods of Watershed 263 that are deeply committed to improving people’s lives, through access to knowledge, gainful employment, healthy food, and a clean, stimulating, and comfortable green environment.  Seeing these dedicated people at work, and being able to support them through partnerships, including those with city agencies, public schools, private institutions, community groups, and NGO’s such as the Parks & People Foundation, has been one of the unalloyed pleasures of ecological research in Baltimore.

All these worthy activities and hard work can be seen as antidotes to the profound disconnectedness that many of these neighborhoods experience.  I draw my roster of disconnections from the writings of social researchers and journalists who have summarized these especially forcefully in recent days.  People in many old city neighborhoods, and in older suburbs, are disconnected from jobs.  Baltimore was a magnet for unskilled but willing workers in its industrial heyday.  Such jobs are largely gone.  Families are disconnected due to laws that stipulate incarceration for even some non-violent crimes.  Students are disconnected from effective learning by the social demands placed on public schools, and by the funding of public schools by the local property tax base.  Homeowners and would-be homeowners are disconnected from access to capital at reasonable rates by predatory lending and by the legacy of early 20th century mortgage restrictions.  Lack of capital or property-based profits affects ownership, repair and maintenance by occupants, and the willingness of absentee landlords to invest in their properties. 

Of particular relevance to the situation in which Mr. Gray found himself is a disconnection from the police.  Other events over the past few years may have left people with the idea that disconnections between the police and communities is a matter of race.  Clearly that is not the case in Baltimore, given the demographics of the city’s population and its police department.  However, there is disconnection nonetheless.  Ta-Nehesi Coates, Baltimore native, memoirist, and social critic, calls out the difference between policing based on authority versus that based purely on power.  Authority would arise from mutual respect and engagement (a rather Lincolnian – of, by, and for).  Power, in contrast, resides in distance and force.  This is not to deny that legitimate authority must sometimes draw upon force.  Others, better suited than I, should be consulted for the nature and significance of this kind of disconnection, which is coming to wider attention these days due to a well publicized litany of harm and mortality arising in the gap between power and authority.  But it is the disconnection currently most obvious on the nightly news beamed from Baltimore at convenient helicopter height.

The Deep Roots of Disconnection

As researchers of the long-term, the deep history of disconnection

An abandoned rowhouse
in Sandtown. The graffito
reads "Sadtown."

becomes apparent in such places as Sandtown.  The riots following Mr. Gray’s funeral are a contemporary echo of literally centuries of disconnection weighing on the population of Sandtown (or Watts, or the South Side, or Hough, or name-the-disconnected-areas in any number of other towns and cities).  Baltimore’s history of differential disconnection is storied, but not unique.  As a thumbnail sketch: 

First, of course, is the long fact and persistent shadow of slavery.  The period of slavery in the United States is much longer than the period of emancipation.  The commodification and capitalization of individual humans of African or mixed African and other descent, was simply the largest single source of wealth in the Antebellum United States.  The brief hope of Reconstruction after the Civil War gave way to a retaking of power (yes, power, as defined above), by those whose economic interests and social status had been damaged by the Civil War and its outcome.  The terrorism, legal exclusion, and absence of opportunity in the South in part fueled the Great Migration, the largest movement of people in the history of the United States.  Lasting, according to some scholars, from the 1880s through the 1960s, the Great Migration saw the exodus of African Americans from the South to cities to the north and west.  Washington DC, and Baltimore, although thought of as southern cities, were destinations in the Great Migration.  

The resulting changes in urban demography, employment patterns, and settlement patterns were major and sometimes long lasting events in the receiving cities.  For example, the creation of American sociology at the University of Chicago had as one of its foci the mechanisms and patterns of change occasioned by the migration of new residents from the American South and Eastern and Southern Europe.  The previous experience of cities and urbanists with such change had been with the relatively more homogeneous and familiar immigrations from Northern and Western Europe.  The unfamiliar arrivals, who were not schooled in urban living, seemed to discomfit the Chicago scholars, whose early writing embodied, to my reading a kind of racist reaction. 

In Baltimore at the beginning of the Great Migration, the city was, at the coarse scale, relatively integrated.  African Americans did experience fine scale segregation, being housed in meager alley houses, while their employers lived in more capacious and well appointed dwellings fronting larger streets.  The arrival of new migrants from the South caused a disruption of Baltimore’s racial patterns.  A series of policies and practices were put in place to purposefully segregate the growing African American population.  First, was the ordinance forbidding integration at the city block level.  Although the ordinance was declared unconstitutional by the Supreme Court a few years after it was established, the replacement activities were harder to dismantle.  Among these was exclusionary zoning, in which industrial zoning was concentrated in areas from which the removal of African Americans or other recent immigrants was desired.  Also in the tool kit were deed covenants which forbade selling to African Americans or Jews.  Neighborhood Associations were established to help prevent “incursions” of African Americans.  And perhaps most notorious of these prejudicial tools was the Federal Home Owners Loan Corporation (HOLC) rating of neighborhoods by credit worthiness.  Mortgages were not encouraged in areas receiving low ratings.  Low grades were bestowed, by definition, on the presence or risk of incursion by African Americans.  Age and size of housing stock were also included.  Even after World War II, with its segregation of the Armed Forces, the benefits of service were effectively preferentially available to white veterans.  The GI Bill, and access to mortgage tax credits are two such benefits, and these benefits opened the suburbs with their subsidized expressways, to those who qualified demographically.

The neighborhoods in Baltimore city clustered near downtown are some of the most conspicuous loci of the disconnections sketched above.  I think it is legitimate to call all of this the long shadow of slavery – the originally constitutional commodification of most African Americans, and the purposeful and continual disconnection of this group of persons from access to the organs of state, of policy, of capital, and of mobility. 

Seeing Connection

As desperate as the need for multifaceted connection in Sandtown and other neighborhoods continues to be, what does ecology have to contribute?  Little on the list of disconnection is under our control.  But, perhaps part of what ecology can do is honor the residents of all neighborhoods in Baltimore with knowledge and experience in the kinds of connection that we study and understand. This may seem like Gahndian idealism, and count for little in the face of accumulated anger and fear, sudden death and riot.  But perhaps the science of connection can help people to envision change, to see how they are linked to a larger and longer world, in which their future matters. 

Analysis of potential areas
available to plant trees (left panel),
a scenario for increasing tree
cover (right panel).

Part of that larger world is the unseen urban ecology, that is the underappreciated role of water, air, organisms, substrates – and differential connections – in the urban matrix.  Part of that larger world is social and historical.  We have shared findings that can help people move beyond myths that trees are associated with crime, and have documented how environmental inequities were created by the zoning process when Baltimore city was majority white, and have shown how amenities and hazards are currently differentially distributed in Baltimore’s underserved white and African American neighborhoods.  We have helped people understand the buried streams in their neighborhoods, and the relationship of what they plant to a milder local climate and the quality of water flowing toward their beloved bay – and crabs. 

Our contributions may help people whose horizons are painfully close, to see some connections to the larger world.  Maybe that’s a step in empowering people to claim more of the roster of connections that can overcome the long shadow of exclusion that falls so oppressively on people and places we love in Baltimore.

Some Background Sources

Boone, Christopher G. 2002. An assessment and explanation of environmental inequity in Baltimore. Urban Geography 23  581-595.

Boone, Christopher G., G. B. Buckley, J. M. Grove, and C. Sister. 2010. Parks and people: an environmental justice inquiry in Baltimore, Maryland. Annals of the Association of American Geographers.

Coates, Ta-Nehesi.  2015. “The Myth of Police Reform”

http://www.theatlantic.com/politics/archive/2015/04/the-myth-of-police-reform/390057/

Coates, Ta-Nehesi. 2009. The Beautiful Struggle: A Father, Two Sons, and an Unlikely Road to Manhood.  Spiegel & Grau.

Coates, Ta-Nehesi.  2014. “The Case for Reparations”

http://www.theatlantic.com/features/archive/2014/05/the-case-for-reparations/361631/

Friedersdorf, Connor. 2015. “Two States of Emergency in Baltimore”

http://www.theatlantic.com/politics/archive/2015/04/what-policing-justice-in-baltimore-requires/391598/

Geldenhuys, Odette. 1995.  “Housing Segregation: Apartheid in Baltimore.” Baltimore Sun. Tribunedigital-Baltimoresun, March 17, 1995. http://articles.baltimoresun.com/1995-03-17/news/1995076191_1_racial-segregation-zoning-ordinance-apartheid.

Graham, David.  2015. “The Paradox at the Heart of Police Brutality Protests”

http://www.theatlantic.com/politics/archive/2015/04/the-paradox-at-the-heart-of-police-brutality-protests/391637/

Light, Jennifer S. 2009. The nature of cities: ecological visions and the American urban professions 1920-1960. Johns Hopkins University Press, Baltimore.

Lord, Charles and K. Norquist. 2010. Cities as emergent systems: race as a rule in organized complexity. Environmental Law 40:551-596.

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 Home to ‘Lot of Fries’

New York Times.  2015.  “Hard but Hopeful Home to ‘Lot of Freddies’”

http://www.nytimes.com/2015/05/03/us/sandtown-winchester-baltimore-home-to-a-lot-of-freddie-grays.html

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