Urban Ecology HAS Changed

A Perspective on Points from Ramalho and Hobbs, As Reported by the BBC on 6 December 2011

A news report by the BBC on an article critical of urban ecology appears at http://www.bbc.co.uk/news/science-environment-16032471  I find that the report, though true to the article by Ramalho and Hobbs, should not go without comment.  Urban ecology is not the backward pursuit that the report might lead some to believe.  The original article by Ramalho and Hobbs, entitled “Time for a change: dynamic urban ecology,” appears in TREE at http://www.sciencedirect.com/science/article/pii/S0169534711003028

A published reply, to which I contributed, also exists.  Mark J. McDonnell, Amy K. Hahs, and I have offered a reply to the original article by Ramalho and Hobbs.  The reply has been accepted by TREE, and is published online at http://www.sciencedirect.com/science/article/pii/S0169534712000286

Changed Already

From the BBC report: “The way researchers assess urban ecology needs to change in order to take into account the way modern cities are developing.” 

The discredited Burgess urban ring model.

Urban ecology has in fact already changed drastically over the last two decades, both because of committed long-term support for urban ecological research, and the closer integration of social and biophysical research efforts.  Since the early 1990’s, when urban ecology was reinvigorated both as a component of mainstream ecology and as an important “boundary discipline” capable of linking ecology with social sciences and with urban design, the field has gone well beyond the concepts and approaches that were available in the mid 1980s and early 1990s.  

Furthermore, urban ecology has productively employed spatially realistic and flexible models that recognize urban areas as shifting, patchy mosaics.  Complaining about ring models, such as the holdovers from the Chicago School, or about linear transects as research tools, misses much of the conceptual and empirical progress of two decades of contemporary urban ecology.

Diverse Urban Transformations

Shenzen, China. (c. Brian P. McGrath)

Interaction among bioecological researchers, social scientists, and urban designers, among others, has firmly embedded within ecological thinking the variety of modes by which cities now change.  There are shrinking, post-industrial cities, burgeoning refugee cities and districts, virtually instant cities in Asia and Africa, and even high density settlements far from traditional urban centers but which through dynamic diasporas that ebb and flow, rely on resources, capital, attitudes, and opportunities that originated in the more classically recognized cities.

Non-linear Models

The simplistic way that urban rural gradients have been interpreted by many is a disappointment.  However, there have been repeated efforts to clarify that a linear transect for studying a spatially complex mosaic is not necessarily the same thing as an urban-rural gradient (Cadenasso et al. 2006).  The vintage of the gradient concept in ecology and the sophisticated and well established strategies for studying complex environmental gradients in spatially patchy contexts (Austin 2005, Fox et al. 2011) would seem to make it unnecessary to emphasize the non-congruence of gradients and transects.  Yet, the conflation is a common one. It is no less correct for being common.  Again, the literature has more depth and richness than Ramalho and Hobbs or their BBC correspondent seem to recognize.

Contemporary Patterns

The BBC correspondent states Ramalho “explained that, historically, cities grew slowly in a relatively compact manner, through progressive rings of urban development.”  The ring model, developed in the 1920s, was almost immediately critiqued by social scientists, and improved as a sectoral model even in the 1930s.  So the insight that the concentric ring model of urban development is flawed is not a new discovery.

Contemporary patterns are said to be ‘markedly different’ from the allegedly slow, ring-like march.  The description that then appears is one of a complex, heterogeneous mosaic that includes green, blue, grey, and brown components intermingling spatially.  Ramalho is further quoted in the BBC report: “Cities are growing very rapidly, they are increasingly expansive and dispersed, sprawling in … spider-like configurations across large distances, and embedding fragments of other land uses in the rapidly changing landscape.”  (Note, ellipsis in original BBC quote.)

Is this a new insight?  Hardly.  Consider this quotation from pg 128 from Pickett et al. (2001):

Thimphu, Bhutan. Doubling in 6 yr

“Cities are no longer compact, isodiametric aggregations; rather, they sprawl in fractal or spider-like configurations (Makse et al. 1995). Consequently, urban areas increasingly abut and interdigitate with wild lands. Indeed, even for many rapidly growing metropolitan areas, the suburban zones are growing faster than other zones (Katz & Bradley 1999). The resulting new forms of urban development, including edge cities (Garreau 1991) and housing interspersed in forest, shrubland, and desert habitats, bring people possessing equity generated in urban systems, expressing urban habits, and drawing upon urban experiences, into daily contact with habitats formerly controlled by agriculturalists, foresters, and conservationists (Bradley 1995).”

It is interesting that the early concentric ring model for Chicago was in fact developed to explain and intervene in the explosive development of that city in the early 20th century: Chicago had doubled in population in a decade due to immigration from novel sources: southern and eastern Europe, and African Americans from the southern U.S.  So speed of growth is not in fact a uniquely contemporary phenomenon.  

Simple Categories?

It is manifestly true that just calling something urban, or suburban, or rural, yields little insight into what drivers may actually be in play.  However, the call for using environmentally meaningful and measurable factors to understand the effects of urban structure and urban change is not new (Pickett 1993).  Indeed, we can point to developments that seek to unpack the metaphorical labels often used in urban ecology research (McIntyre et al. 2000).  The concept of the “ecology of prestige” (Grove et al. 2006b), and a novel, integrated conceptualization of urban land covers (Cadenasso et al. 2007) are examples. 

Furthermore, social complexity is recognized as a driver through such things as property regimes (Grove et al. 2005), and through institutional structures and indeed of networks of organizations (Ostrom 1990). 

Urban ecologists and social scientists have also recognized the impact of spatial context on the various patches within urban mosaics, whether they are natural, built, or the still more common hybrid patches (Grove et al. 2006a, Cadenasso and Pickett 2007, Shane 2007).  

A recent approach to factor analysis, based on updating a classical conceptual model originally developed in soil science, also illustrates how urban ecologists have been approaching this problem (Pickett and Cadenasso 2009).  Both social and biophysical factors are addressed in this framework.  Such a hierarchical framework can accommodate the sharper focus, that is, attention to detailed driving variables, as well as the aggregated variables which are sometimes useful for coarse scale analyses and comparisons.  Such a flexible, hierarchical approach has been called for by urban ecologists in the past (Wu and David 2002).

Urban Change

Change landscapes in shifting urban mosaics.

The long-term perspective illustrated by such studies as BES and the Central Arizona Phoenix LTERs has been a crucial addition to contemporary urban ecology (Grimm et al. 2000).  The role of social, political, and biophysical legacies, and the resultant path dependencies are well recognized features of urban systems (Bain and Brush 2004).  Such legacies must be considered when bringing ecological knowledge to bear in understanding and improving urban systems.  The growing data on temporal changes are already an important part of contemporary urban ecology (Boone et al. 2009, Grove 2009).  This information is not only important for conservation of native and managed biodiversity, but for designing and managing for greater urban sustainability in the future (McGrath et al. 2007).

The Bottom Line

While Ramalho and Hobbs identify many positive attributes of a contemporary urban ecology, I believe that these are already in place, and are exemplified by a lot of the work in BES as well as other urban ecology efforts around the world.  The sophistication and evolution of contemporary urban ecology as an integrated, socio-ecological pursuit (Cadenasso and Pickett 2008), but which brings the best of mainstream ecology together with cutting edge social science and urban design should be more widely recognized. 

Literature Cited

Austin, M. P. 2005. Vegetation and environment: discontinuities and continuities. Pages 52-84 in E. van der Maarel, editor. Vegetation ecology. Blackwell Science, Malden, MA.

Bain, D. J. and G. S. Brush. 2004. Placing the pieces: reconstructing the original property mosaic in a warrant and patent watershed. Landscape Ecology 19:843-856.

Boone, C. G., M. L. Cadenasso, J. M. Grove, K. Schwarz, and G. L. Buckley. 2009. Landscape, vegetation characteristics, and group identity in an urban and suburban watershed: why the 60s matter. Urban Ecosystems 13:255-271.

Cadenasso, M. L. and S. T. A. Pickett. 2007. Boundaries as structural and functional entities in landscapes: understanding flows in ecology and urban design. Pages 116-131 in B. McGrath, V. Marshall, M. L. Cadenasso, J. M. Grove, S. T. A. Pickett, R. Plunz, and J. Towers, editors. Designing patch dynamics. Columbia, Graduate School of Architecture, Planning and Preservation, New York, NY.

Cadenasso, M. L. and S. T. A. Pickett. 2008. Urban principles for ecological landscape design and management: scientific fundamentals. Cities and the Environment 1:Article 4.

Cadenasso, M. L., S. T. A. Pickett, and J. M. Grove. 2006. Integrative approaches to investigating human-natural systems: the Baltimore Ecosystem Study. Natures, Sciences, Soci‚t‚s 14:1-14.

Cadenasso, M. L., S. T. A. Pickett, and K. Schwarz. 2007. Spatial heterogeneity in urban ecosystems: reconceptualizing land cover and a framework for classification. Frontiers in Ecology and Environment 5:80-88.

Fox, G. A., S. M. Scheiner, and M. R. Willig. 2011. Ecological gradient theory: a framework for aligning data and models. Pages 283-307 in S. M. Scheiner and M. R. Willig, editors. The theory of ecology. University of Chicago Press, Chicago.

Grimm, N. B., J. M. Grove, S. T. A. Pickett, and C. L. Redman. 2000. Integrated approaches to long-term studies of urban ecological systems. BioScience 50:571-584.

Grove, J. M. 2009. Cities: managing densely settled social-ecological systems. Pages 281-294 in F. S. Chapin, III, G. P. Kofinas, and C. Folke, editors. Principles of ecosystem stewardship: resilience-based natural resource management in a changing world. Springer, New York.

Grove, J. M., W. R. Burch, Jr., and S. T. A. Pickett. 2005. Social mosaics and urban community forestry in Baltimore, Maryland. Pages 249-273 in R. G. Lee and D. R. Field, editors. Communities and forests: where people meet the land. Oregon State University Press, Crovallis.

Grove, J. M., M. L. Cadenasso, W. R. Burch, Jr., S. T. A. Pickett, K. Schwarz, J. P. M. O'Neill-Dunne, M. A. Wilson, A. Troy, and C. G. Boone. 2006a. Data and methods comparing social structure and vegetation structure of urban neighborhoods in Baltimore, Maryland. Society & Natural Resources 19:117-136.

Grove, J. M., A. R. Troy, J. P. M. O'Neill-Dunne, W. R. Burch, Jr., M. L. Cadenasso, and S. T. A. Pickett. 2006b. Characterization of households and its implications for the vegetation of urban ecosystems. Ecosystems 9:578-597.

McGrath, B. P., V. Marshall, M. L. Cadenasso, J. M. Grove, S. T. A. Pickett, R. Plunz, and J. Towers, editors. 2007. Designing patch dynamics. Columbia University Graduate School of Architecture, Preservation and Planning, New York.

McIntyre, N. E., K. Knowles-Yanez, and D. Hope. 2000. Urban ecology as an interdisciplinary field: differences in the use of "urban" between the social and natural sciences. Urban Ecosystems 4:5-24.

Ostrom, E. 1990. Governing the commons: the evolution of institutions for collective action. Cambridge University Press, New York.

Pickett, S. T. A. 1993. An ecological perspective on population change and land use. Pages 37-41 in C. L. Jolly and B. B. Torrey, editors. Population and land use in developing countries: report of a workshop. National Academy Press, Washington, DC.

Pickett, S. T. A. and M. L. Cadenasso. 2009. Altered resources, disturbance, and heterogeneity: a framework for comparing urban and non-urban soils. Urban Ecosystems 12:23-44.

Pickett, S. T. A., M. L. Cadenasso, J. M. Grove, C. H. Nilon, R. V. Pouyat, W. C. Zipperer, and R. Costanza. 2001. Urban ecological systems: linking terrestrial ecological, physical, and socioeconomic components of metropolitan areas. Annual Review of Ecology and Systematics 32:127-157.

Shane, D. G. 2007. Urban patches: granulation, patterns and patchworks. Pages 94-103 in B. McGrath, V. Marshall, M. L. Cadenasso, J. M. Grove, S. T. A. Pickett, R. Plunz, and J. Towers, editors. Designing patch dynamics. Columbia, Graduate School of Architecture, Planning, and Preservation, New York, NY.

Wu, J. G. and J. L. David. 2002. A spatially explicit hierarchical approach to modeling complex ecological systems: theory and applications. Ecological Modelling 153:7-26.

Post-Industrial Baltimore

Baltimore is often called a “post-industrial” urban region.  What set of cultural and theoretical assumptions does this label invoke?  The industrial and post-industrial tag emerges from the Modernist program and discontent with it.

What is Modernism?

The industry window at Zion Church

The cultural program of Modernism, which like any cultural program is a mix of theoretical assumptions, assertions of boosters, and a vernacular mythology, is a view that held sway from the late 19th through mid-20th centuries.  Modernism involves assumptions that progress, driven by industrialization and urbanization, improve society and result in a sequence of development.  At the pinnacle of that development was the north temperate, industrial metropolis.  Although initial examples of industrial development led to dangerous, polluted, and disease ridden settlements, the leavening of progressive urban reformers in the late 19th century ushered in the “sanitary city.”  The sanitary city ideal mitigated the ills of the industrial city, and is most often what people think of when they envision a “modern” city.  Such cities suffer less from local pollution, treat wastes released downstream and downwind, provide effective infrastructure for transportation and sanitation, and ideally contain some natural amenities for the benefit of citizens, for example.

Discontent with Modernism

There are at least two problems with the Modernist development model.  One is that there has proven to be something “after” the modern.  Of course that doesn’t mean something beyond time, but it does suggest that the development model has shortcomings.  The Modernist, industrial city was assumed to be the epitome of national and regional development.  Perhaps people thought that once achieved, such a modern city would persist indefinitely.  Now it is clear that is not the case.  Industrial, sanitary cities in many north temperate regions have retreated from the high economic activity, population density, and investment in infrastructure and buildings that they enjoyed at their zeniths.  Former industrial powerhouses in the Midwestern and Northeastern US, or in eastern Germany and Europe, have slipped in size, productivity, and prestige.  They have become post-industrial.

An Opening for Sustainability

Baltimore City's Sustainability Website

Of course, the wisest cities, including Baltimore, are poised and actively attempting to take advantage of this shift as an opportunity to become more sustainable and to provide an attractive and safe social, economic, and biophysical environment for old and new citizens.  So there can be positive outcomes of the shift from the industrial ideal.

Global Failure of Modernism

The second shortcoming of the Modernist development model is its application on the global scale.  It appears in the damning phrase, “developing country.”  This application seems to assume that all human settlements will evolve through some deterministic sequence, for example, from bucolic agricultural commodity markets, through raucous trading centers, and ultimately to efficient industrial production machines.  Associated with this shift is the human demographic transition, in which the initially high birth and mortality rates associated with more agricultural life styles are gradually replaced by low birth and death rates per capita with improved sanitation, medical care, access to education, and the shift from farm to diverse forms of industrial labor.  

A Capetown, South Africa township.

The assumptions of deterministic development seem to poorly match the reality in many parts of the world.  Northern hemisphere industrial and labor development in fact exploited locally equable climates, abundant water for drinking, power, and transport, and drew on resources and people from elsewhere.  In particular, industrial production continues to draw on globally distributed oil, gas, and now even biomass stocks.  Do the “developing” countries have access to this kind of resource base?  By what vulnerabilities are settlements in the Global South, located as they often are in arid and semi-arid regions, or low lying coastal zones, constrained?  Are contemporary populations in the “developing” world fixed or mobile relative to regional economic opportunities?  The differences, some just now emerging, between the tidy model of development derived from the Global North, and the novelty and diversity of motivations and forms of urbanization in the Global South, suggest that the Modernist narrative, and the mercantile to industrial to sanitary city transition, has limits in understanding urbanization as it now exists throughout the world.

Understanding Urbanization without Modernism

Our post-industrial city, and improved understanding by comparing it with the diverse forms, social, and ecological implications of urbanization throughout the world, can both benefit by acknowledging the limits of the Modernist development model.  Our participation in the Research Coordination Network for Urban Sustainability is one tool to advance the theory and practice of urbanism without recourse to the Modernist conceptual and political model.

The Year of Adaptive Processes

The new theme for research in BES emphasizes adaptive processes as a key to understanding and working with urban sustainability.  Because of its importance, the intellectual theme for BES this year will be socio-ecological adaptive processes.

From Sanitary to Sustainable: The Guiding Idea

To review a bit, BES III takes the transformation from the sanitary to the sustainable city as a major ongoing environmental shift that has the potential to affect all aspects of the city-suburban-exurban system of Baltimore.  Sustainability is a socially agreed upon set of goals that accounts for environmental, social, and economic health of the total urban ecosystem.  It necessarily incorporates social values.  

The Science Supporting Sustainability

But what scientific information is needed to advance sustainability, and to evaluate the degree of success in achieving sustainability?  The concept of resilience, which is both a powerful metaphor of change and adjustment is the next link in the intellectual path to understanding and working with sustainability.  Resilience, as mentioned earlier in this Web Log (http://besdirector.blogspot.com/2011/01/resilience-ecology-evolution-and.html) is the ability of a system to experience internal and external shocks and still adjust and persist in a dynamic form.  Resilience can have socially desirable and socially undesirable outcomes, and that is judged against the three-pronged sustainability goals chosen.  The system of automobile based transport in metropolitan America is resilient, but in some ways, an environmentally unfortunate one.  Wetlands are a resilient aspect of coastal systems affected by hurricanes and storm surges.  Resilience per se is neither good nor bad.  Sustainability, when the goals are well chosen, may admittedly involve trade offs, but at least those trade offs must not neglect off hand such things as social equity and ecological function.

Making Resilience Work

Figure 1: The Adaptive Cycle

Resilience is on the one hand, a metaphorical conception, and on the other a very general theoretical framework cast in the form of the “adaptive cycle” (Figure 1).  How does such a general concept get translated into something that can be measured and tracked?  The answer is to use adaptive processes to fill in the details of how systems develop, how they react to stresses and disturbances, and how they periodically reorganize.

Resilience Depends on Adaptation

What are adaptive processes?  They are the structures, fluxes, and interactions that allow systems to adjust to sudden or gradual changes.  Social and biogeophysical features can contribute to the adaptive capacity of urban systems.  The literature suggests a number of general kinds of adaptive processes (Figure 2).  It is these features which BES needs to concentrate on in the coming year.  How do our ongoing, long-term measurements support the scheme of adaptive processes?  What kinds of trends can be determined and can they be interpreted in terms of the resilience cycle and socially described sustainability goals?  What new measurements or analyses might be required?  Are there clear parallels between various social and biophysical adaptive processes?

Figure 2. The determinants of adaptive capacity, shown as adaptive processes in social and biophysical realms.  Of course the processes in the two realms interact.

Toward Improved Understanding of Adaptive Processes

Over the coming year, discussion of adaptive processes should suffuse all our activities and research discussions.  Then, during our annual meeting in October, we may be in a better position to evaluate the state of adaptive processes, and to understand how they affect the transition from the sanitary to the sustainable city.  Addressing this issue will undoubtedly take a long time.  It’s a good time to start.

Natural Experiments of History

The title of this essay is the same as a book edited by Jared Diamond and James A. Robinson, published in 2010 by Harvard University Press.  The book explores the general method of natural experiments applied to human societies and history.  It was tempting to title this essay "Cultural Experiments," because the emphasis of their book is on inhabited places, social institutions, and human actions.  But the cognitive dissonance of natural, experiment, and history in one title is an appropriate mental stimulus for the message they present. 

Experiments are controlled comparisons deliberately set up to expose the effect on one or a very few variables on some structure or process.  Greatest confidence is afforded by laboratory experiments where all external conditions can be held constant, or field experiments where even the conditions outdoors are kept as constant as possible while varying the presumed cause.  A randomized comparison between a treatment and a control is still the statistically most unassailable approach.  However, even with this paragon of knowledge creation, great creativity must be brought to bear to ensure that the external conditions are indeed well known and no causative factors are left unaccounted for.  Furthermore, there is a trade off between rigor and realism in experiments.  The more controlled a situation is the greater the distance from messy reality.

Patterson Park, Baltimore

Experiments in Culture and History

What are researchers to do if they can't control the environment and vary one or two factors at a time?  After all, history can't be redone, and there are ethical constraints to manipulation in inhabited systems.  Many people have assumed that this means the power of experimentation is unavailable in such situations.  This would disadvantage those who are interested in complex systems, in much of human agency, and in historical causation.  What influence do the conditions of the past have on the outcomes in the present?  

This is the problem that Diamond and Robinson address.  They open and close the book with chapters outlining the issues and summarizing the successful strategies for dealing with found or natural experiments.  Indeed, the cultural and historical comparisons, and the comparisons of socio-ecological conditions that the book presents are far from some haphazard stumbling across a good comparison that has the hallmarks of an experiment.  Great care is taken in evaluating the similarities and differences among the control and the treatment historical or initial conditions.

In addition to the introductory and closing chapters, the book addresses several cases:

• ·         Polynesian cultural evolution,

• ·         Frontier boom/bust cycles,

• ·         Banking institutions and development,

• ·         Comparisons of environment and social controls on Pacific islands,

• ·         The consequences of the slave trade in Africa,

• ·         How colonial land tenure practices influences current public goods,

• ·         The role of the French revolution in speeding the transition to capitalism.

Baltimore: Boom and Bust on Frontier?

The chapters are written in a very approachable style while at the same time explaining the rigorous assessment of conditions to ensure the validity of the comparisons.  All repay attention.  However, perhaps of greatest relevance to the Baltimore Ecosystem Study, with our new emphasis on the transition from the sanitary to the sustainable city, is the chapter by James Belich on "Exploding Wests: Boom and Bust in Nineteenth-Century Settler Societies" (pages 53-87).  The chapter covers the American West, and the British "West" consisting of Canada, Australia, New Zealand, and South Africa.  The transfer of human, financial, and material capital from an established metropolitan area to a frontier, with an associated increase in vectors of mass transfer; media and modes of communication; and booster institutions and businesses characterize booms.  The creation of local infrastructure during a boom is a major commitment.  Busts, crashes, or panics, on the other hand are characterized by reduced human population growth and reduced economic growth.  They can last for two to ten years, and generate by an economy dominated by new or increased exports.  The "conquest of distance" is a feature of successful export recoveries.

There are repeated cycles of boom and bust throughout the global, Anglo-American Wests.  What relevance does this kind of thinking have for the transition from the post-industrial, sanitary city to the sustainable city of the future?  It's a question we should consider.  And attention to the methodology of cultural or natural experiments in an urban LTER is also an important matter.  So this book has double relevance to BES.