The short answer is "Not just
in Baltimore." Let's explore this
more deeply. A school of thought is a
broad way of thinking, a strategy for research, and an approach to problem solving that
applies across a topic area. A school of
thought may be named for a particular place where it originated while applying
to any place where its assumptions are met.
So the Baltimore School of Urban Ecological Science is a way of thinking
that potentially applies to urban, urbanizing, and changing urban places
anyplace on Earth.
Four Broad Propositions of the
Baltimore School
To examine the potential for broad
application, the nature of the Baltimore School must be described. According to Grove and colleagues (2015), the
Baltimore School rests on four big theoretical propositions.
- Urban ecological science addresses
the whole urban mosaic, not just the green spots.
- Urban systems are complex in
space, time, and organization.
- It is an integrative pursuit
dealing with whole urban areas as human-ecological-technological systems.
- Ecology of cities is useful for
both scientific understanding and decision making.
The first three propositions embody
many more specific scientific assumptions, frameworks, and concepts, while the
fourth emphasizes the integration of science with decision making as a
co-produced goal and outcome. These four propositions and their more specific assumptions together show
what the Baltimore School is and why it can apply so broadly.
The task of testing the broad relevance
of the Baltimore School rests on the meaning and applicability of the four
theoretical propositions. The Baltimore
School would be relevant wherever these four propositions or tenets hold.
Comprehensive mosaics
 |
| Union Square corner |
Although urban places were for
centuries walled and distinct features of landscapes and regions, differing in
structure and activities from surrounding rural, pastoral, or wild lands, this
distinction has virtually dissolved over the last century (Lefebvre
2003, Gandy 2014). Of course even
ancient, Medieval, or Baroque cities had contrasting districts within them,
represented by the familiar term "quarter" still heard in many
cities. But to this fine scale and
confined mosaic of structure and use, contemporary cities add many layers of
heterogeneity. And such heterogeneity is
seen in various aspects of urban form, for example. It is common now to speak of various
"shades" of infrastructure -- green for vegetation, blue for water
and wetlands, gray for buildings or pavement.
There are also spatially distributed social structures and
infrastructures, and of course some technological infrastructures such as wires
and wireless aren't usually represented by a color, being virtually invisible
to most urbanites. Yet these various
constructed, biological, and social elements are combined in different ways
across a city, suburban, and exurban region.
Indeed urban infrastructures in the largest sense also reach into
seemingly rural parts of urban regions.
Urban systems are therefore now
mosaics of all these various features, and their patchy structures 1) exhibit
different kinds and degrees of connection, 2) support or dampen flows of
materials, energy, organisms, and information, and 3) change over various time
scales (McGrath and Shane 2012, Boone et al. 2014). These extensive mosaics are the subject of
urban science and are the motivation for investigating the ecology of the city (Pickett
et al. 1997, Grimm et al. 2000), where the term city stands for all the
kinds and locations of elements listed above.
Complex in Space, Time,
and Organization
A comprehensive mosaic such as that
described under proposition one must be considered a complex system in the
sense of encompassing different scales, of possessing non-linear interactions
and feedbacks, undergoing adaptation and learning, and exhibiting open ended
trajectories of change. Complexity is
thus different from complicatedness, which characterizes systems that may have
many interacting parts, but in which the interactions are fixed and functions,
goals, or end points are clear (Allen and Hoekstra 2015). Cities are clearly systems of the complex
type.
Complexity can be conceived of as
having three conceptual dimensions (Cadenasso et al. 2006). Space, time, and organization. Each dimension can be represented by a nested
hierarchy ranging from relatively less to relatively more complex
situations.
Spatial
complexity begins with a focus on individual locations or patches. The simplest description of a spatial mosaic
is to enumerate the kinds of patches or spatial units it contains. Increasing complexity emerges from
understanding the frequency of each of the types of units. Further complexity appears when the spatial
configuration or adjacencies of the patches are accounted for. The next step of spatial complexity is to
document patch change, which may involve appearance of new patch types,
disappearance of existing patch types, or the merging or splitting of different
patches. Finally, accounting for all
these lower levels of complexity the shifting mosaic or fully patch dynamic
system can be addressed. This dimension
of complexity might also be called complexity
of configuration since that idea encompasses and depends upon the specific
steps of complexity laid out just above.
 |
| W 29th Street, Baltimore |
Temporal
complexity exists when research and practical concern extends from focus on
the here and now, with the interactions that occur instantaneously in that
scope, to increasing depths of time and history. As complexity addresses additional time
periods, such things as echoes of past events or conditions, legacies of prior
social or biophysical regimes, and finally the emergence of interactions that
take a long time to come to fruition appear for analysis and may impact
management (Boone 2007, Grove et al. 2017). Scenario building takes temporal complexity
as a reality that can be explored via alternative trajectories of change into
the future (Carpenter et al. 2006,
Larondelle et al. 2016). This
complexity can also be labeled complexity of contingency.
Organizational
complexity acknowledges that the control of individual components or
networks of components in an urban system depend on how those units
interact. Along the organizational
dimension, complexity increases a step when neighboring patches come under
consideration. This step implies a third
possible step, the nature of the boundaries between patches, which invokes a
fourth step of flow from patch to patch.
Flows as well as changes within the individual patches are the next step
in complexity, which ends in the capstone consideration of entire spatial patch
mosaics as hosting connectivity and change.
This dimension of complexity suggests several urban applications,
including nested hierarchies of households, neighborhoods, districts,
municipality, and so on, up to a megaregion (Harrison
and Hoyler 2014). The
complexities of space and connection also extend to the entire urbanized globe
through material, energetic, and informational teleconnections (Seto
et al. 2012). Human migration
also knits the spatially complex global urban realm together in increasingly
intimate and sometimes problematic ways.
This dimension of complexity could also be labeled complexity of
connectivity.
Urban systems can exhibit all three
kinds of complexity and may do so over vast extents, involving many social,
political, economic, and technological as well as biophysical conditions. This suggests that urban ecological science
is an interdisciplinary field that engages with many others (McIntyre
et al. 2000, McPhearson et al. 2016).
This idea is made explicit in the next proposition of the Baltimore
School.
Integrated
Social-Ecological-Technological Systems
Ecology has been since its birth as
a scientific field a preeminently integrative, synthetic, and process oriented
one (Kingsland 2005). When applied to urban systems, this
integrative motive is extraordinarily important. Among the many integrative concepts in
ecology, the idea of the ecosystem may express this motivation most
fundamentally. The core term "system"
requires there to be components, interactions, feedbacks, and a stated
boundary. Notably, the boundary may not
be "hard" (Cadenasso et al. 2003). Adding "ecological" to this idea,
represented by the now nearly ubiquitous prefix "eco," took these
requirements into the biological realm.
The ecosystem is defined as the interaction
between a biotic complex, that is, a community of all kinds of organisms, with
a physical complex, that is all the resources, regulating factors, stresses,
and physical signals in a particular space (Pickett
and Cadenasso 2009). Ecological
space was therefore conceived from the beginning as process-based and
integrative. This is quite helpful in
the urban realm, where social scientists and philosophers have for a long time
spoken of the social creation of space in urban areas (Lefebvre
1991). We can now see that there
is also ecological creation of space to go along with that, and the ecosystem
concept carries that conceptual weight successfully. In other words, urban space is co-produced by social and biophysical processes (Rademacher
et al. 2018).
 |
| Ecological Society of America SEEDS student field trip to Balto, 2003 |
Applying the ecosystem idea to
urban systems is important for several reasons.
First, it helps translate the ideas of complex systems to urban
areas. Second, it reminds everybody that
organisms in addition to people are present in all urban places. Third, it invites everybody to recognize and
exploit the work -- both beneficial and burdensome -- that the organisms do in
urban systems. This last point is
important even if the organisms aren't obvious or visible to all.
There are some caveats in using the
ecosystem idea to apply to urban systems.
First, some people have attributed to the ecosystem idea in general what
are actually specific assumptions of particular models or narrow uses of the
general idea. Although these assumptions
may hold in some specific situations, it is not wise to assume that all
ecosystems are in equilibrium, are resistant to change, are self regulating, or
alternatively, that they are delicate and ephemeral, or that they necessarily have
some desired social goal. There are lots
of other kinds of baggage that the term ecosystem sometimes carries, but those
bags are really carried by and should be evaluated in the context of the specific
models that translate the general term to clearly stated situations. This insight comes from a hierarchical view of
general theory, that is supported by more less general or specific models where
the special assumptions actually reside (Cadwallader
1988, Pickett et al. 2007).
So now we can summarize what, in
general terms, an urban ecosystem is following the tenets of the Baltimore
School. This brings together thinking
that has been exercised in various projects and institutions (e.g., Grove 2015,
Pickett et al. 2011, 2019). An urban ecosystem is the interaction among
a biotic component, a physical component, a social component, and a constructed
component. These four components are
very high level generalizations that must be further unpacked or specified to
create a rigorous model of an urban place at any particular scale or
location. Social, as used here, includes
such things as human demography and group identities, economics, power and
politics, culture, and governance. Many
other specific features of the social component could be given. The constructed includes the reshaping of the
land surface, modification of soils and substrates, shifts in hydrological
flows, pipes, wires, buildings, and roads.
Again, more detail of the constructed component can be given in any
particular place. The biotic and the
physical in the urban ecosystem have the same broad meaning as they do in the
original ecosystem definition. But it is
well known that biota and physical features of urban systems can be and very
often are profoundly modified by human products and activities (Pouyat
et al. 2010, Swan et al. 2011).
But to neglect the persistent role of organisms and the deep physical
context is to fail to take advantage of cities at least in part as ecological
systems (Spirn 1984, 2012). Among other things, neglecting the biological
and the physical:
- reduces the likelihood of successful
"nature based solutions" to urban problems,
- neglects the biological capacities to reduce the
work required of gray infrastructure,
- neglects people's delight in the biota of their
city, suburban, and exurban places, or
- obscures the impact of rare extreme natural
events.
Use-Inspired Basic
Research: Ecology For the City
Discussing how the ecosystem
concept resonates with the ancient architectural criteria of "firmness,
commodity, and delight" (translated from the Roman architect and engineer,
Vitruvius, 1st century BCE). These three desiderata of the built environment have implications for how we view a city
through an ecological lens, and highlight the proposition that urban ecological
science has contributions to make to solving practical problems in urban
areas. This ancient triumvirate of
characteristics from architecture points to some appropriate desires for the four
components -- biotic, physical, social, and constructed -- of urban
ecosystems. Firmness of course means that the components will be safe, sound,
and reliable. How does this apply to the
biotic and the constructed components of urban systems? The concepts of resilience and robustness
link this to contemporary urban concerns.
These ecological aspects of the ecosystem components point to the fact
that firmness does not mean unchanging. Commodity refers to the utility,
function, or outcomes of the parts of the urban ecosystem. Here contemporary parlance might speak of the
social program of designed or planned parts of a city-suburb-exurb. But the three pillars of sustainability help
spotlight economic vitality, environmental benefits, and social equitability of
urban features and plans. Delight or beauty, clearly in the eyes
of the beholders, speaks to such things as cultural and restorative ecosystem
services, psychological well being, and other contributions of all components
of urban ecosystems to quality of human and other-than-human lives in urban
regions.
The Baltimore School emerged in
part from the desire to address the practical and pressing concerns to improve
the quality of life throughout the city region -- but not neglecting underserved,
minority and poor neighborhoods -- to improve the quality of environment
downstream in the impaired waters of the Chesapeake Bay, and to provide
non-governmental organizations, government agencies, and the local school
systems with reliable scientific information.
It is clear that similar goals can be found for old and emerging cities
around the globe. In meeting these
practical goals, the Baltimore School became a trusted venue -- not necessarily
always a physical location -- but an intellectually open community, to
facilitate conversations among organizations and agencies in the region that
sometimes were siloed and isolated.
This tenet can be summarized in the
phrase "ecology for the city" (Childers
et al. 2015). Two caveats: First
city, as throughout this essay, refers to all parts of a large, comprehensive
urban region. Second, "for"
does not mean a top down, one size fits all, or paternalistic approach to
generating and applying ecological insights in urban areas. Rather for means with. With implies that some
research questions, study approaches, analyses, and interpretations will be
co-produced by scientists working with communities, civic organizations, and
government agencies (Muñoz-Erickson et al. 2017). Educational curricula will likewise be
developed in collaboration with teachers and school administrators.
Difference From Other
Urban Schools.
This section is something of an interlude. The cymbal crash has occurred just
above. This essay has endeavored to show
that the Baltimore School is not just a child or advocate of one metropolitan
region in one country. Rather, it is a
way of thinking that can be used anywhere.
But how does it differ from other schools of urban ecology? This discussion isn't meant to identify all
possible named schools of urban ecology.
In fact, some schools might be considered schools of urbanism, which often
rest on architectural, planning, design, social, and economic concerns rather
than environmental or ecological ones (e.g., Ellin 2006, McGrath 2013).
The Chicago School
The reason that most people talk
about urban schools at all is the Chicago School of Urban Sociology. Some sources call this a school of urban
ecology, however. This was the
pioneering school of urban sociology in the United States, flourishing in the
first two decades of the twentieth century (Burgess
1925). A product of the first
department of sociology in the United States, the professors borrowed many
analogies from the predominant plant ecology of the time (Light
2009). Communities as units,
succession or linear, deterministic dynamics of communities through time, and a
distinct spatial zonation of human communities in Chicago were some of the most
important ideas of the Chicago School (Cadenasso and Pickett 2013). As early as the 1930s and continuing into the
mid-twentieth century, the Chicagoans were criticized for over-idealizing the
spatial and deterministic transitions, and for neglecting human behavior, for
example (Hawley 1986, Burch et al. 2017). Critics thought that space was being used as
a determinant, rather than a stage for more subtle, open-ended human
interactions. In addition, the idea of
urban life cycles, brought in by analogy from ecology, was used as late as the
1960s to justify federal funding of massive neighborhood replacement and
highway building that has often disadvantaged poor and minority groups. Unfortunately, the fact that the term ecology
is sometimes used for this school has led the more recent explorations of
ecologists into the city to be tarred with the same broad brush (e.g., Gottdiener
and Hutchison 2000). The
invention of the term Baltimore School was intended to offer a counterweight to
this misinterpretation of urban ecological science.
The Los Angeles School
First articulated in the 1990s, the
Los Angeles School is not primarily an environmental view of the city. However, it does offer an alternative to the
paradigm of modernism that was the context for the formation and legacies of
the Chicago School (Dear and Flusty 1998). It suggested that contemporary structures and
dynamics in large city regions, especially those which emerged predominantly
after World War II, should be understood in terms of post-modernism. Dear and Flusty, for example, highlight the
spatial complexity of post-modern urbanism, the importance of local-global
connections, the strong social differentiation in cities, and the shift of
control from core cities to suburban and exurban institutions and
processes. Although these urbanistic
shifts have environmental implications, making those connections remains a task
for urban ecological science and the interdisciplinary nexus it participates in
(McHale et al. 2015).
Applying the Baltimore School: Summary and Prospects
This essay has drawn on a broad
foundation of urbanist thinking, which is referenced elsewhere (Shane
2005, Pickett et al. 2011, McGrath 2013, Grove et al. 2015). Here we have made three key points.
1. The Baltimore School of Urban
Ecological Science emerged from work, experience, and practice in Baltimore,
but it applies to any situation where its tenets hold. It addresses places where systems are
co-produced by social and biophysical processes.
2. The tenets are that first urban areas are comprehensive and
extensive urban ecosystems, best studied as complete mosaics of land, cover,
and habitat types; second urban
systems are complex in the technical sense along dimensions of space, time, and
organization (that is configuration, contingency, and connectivity); third they are integrated social
ecological systems (equivalently labeled as human ecosystems or
social-ecological-technological systems); and fourth the perspectives above and the empirical understanding they
support is useful for co-produced decision making by individuals, households,
organizations, and government agencies.
3. These tenets, as theoretical
propositions and paradigmatic assumptions, are clearly broadly relevant to
urban areas across the globe, and at any scale of settlement structure and
connectivity. Therefore the Baltimore
School stands for a universal social-ecological conceptual and epistemological
device that can structure urban ecological science in any location.
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For an earlier post with background
information, see also https://besdirector.blogspot.com/2015/12/a-new-school-of-urban-ecology.html
Steward Pickett, Director Emeritus
