Sunday, May 19, 2013

What Does Collapse Tell Us About Resilience?

The adaptve cycle is key to understanding resilience as an integrated ecological and social construct.  The cycle is introduced elsewhere in this Web Log ( as well as briefly defined in the BES Urban Lexicon (  One of the key aspects of the cycle is the movement of systems in a conceptual space defined by the accumulation of capital in the structure of the system, and the increasing complexity of the system at the same time (Figure 1).
Fig. 1. Capital and complexity as two axes of the
adaptive cycle of resilience. r-K contrasts
trace out the blue trajectory.

Ecological Foundation of Increasing Complexity

As an ecologist, I find these these increases easy to understand, since they parallel changes that have long been understood from ecological succession.  One of these shifts is based on resource capture.  Dominance of the plant community shifts from species that specialize in the capture of resources that are freely available in the environment, to dominance by species that specialize in conserving the resources they have already captured.  Think of fast growing, high resource-demanding colonizing species or weeds, compared to slow growing, resource hoarding trees that get by on modest fluxes of nutrients and light.  This kind of contrast is labeled in both plants and animals as r versus K strategies. 

The biological contrast in complexity emerges from the similar successional differences.  For example, later successional communities typically have a larger number of canopy layers, as well as greater spatial heterogeneity.  These patterns result from the growth of long-lived canopy-forming plants, insertion of lower layers dominated by shade-tolerant species, and the emergence of species that spread clonally.  The massive, long-lived, and spatially extensive structures are good at storing and allocating assimilated resources. 

However, the slow growth rates and massive structures associated with dominance in late successional comminities also make those systems vulnerable to external disturbances, such as wind, fire, or disease outbreak.  The same species that manage assimilated resources have evolved structures and processes that ill suit them to deal with environments where resources are freely available.  This is what sets up the adaptive cycle of r-K shift with subsequent release and reorganization.

In social systems, accumulation of capital or wealth is a familiar trajectory.  Settlements are often initiated in sites where resources or the opportunity to concentrate resources is high.  In such situations the external resources, be they rich soil for crops, industrially valuable minerals, or fossil fuels for example, are initially untapped.  As the settlement accumulates more residents and built structure, it assimilates more resources.  Furthermore, urbanization is associated with increasing capacity to assimilate and process more resources.  All this is expressed as wealth embodied in the system.

Driving Complexity in Social Systems

But what strategic contrast might explain the shift in the social complexity of the system?  Joseph Tainter's (1988, 2006) analysis of the collapse of social systems exposes the sources of social complexity.  The built structure of settlements clearly becomes more complex.  In addition to raw density of structures, often the height and heterogeneity of structures increases.  Infrastructure to move people, goods, resources, and wastes is developed.  Specialization of jobs and lifestyles emerges, and the demographic differentiation of the population typically increases as residents are drawn from other settlements or different rural areas.  Of great importance is the elaboration of increasingly layered, spatially extensive administrative and governance structures.  Specialized knowledge and training echo the increasing administrative compelxity.   

This suite of differences, along with many others, consolidate into fixed, self-perpetuating structures that are initially adaptive.  As an already complex society attempts to solve its problems it can only add additional layers or kinds of organizational complexity.  Yet, each new innovation involves a cost that necessarily produces less return on the investment.  Thus, according to Tainter, the growth of complexity in societies will trace out a curve of decreasing marginal return over time.  Once marginal return declines to lower levels, the society is poised to disintegrate because the fixed investment leaves the society vulnerable to such things as resource depletion, invasion, internal unrest, or simply voluntary migration to a less burdensome region.  Environment and resources play a role, but the lens through which the crisis comes into focus is through the economics of marginal return on investment.

Tainter’s model explains the social component of the “front loop” of the adaptive cycle in social-ecological systems.  Many analyses in the literature have focused on the inertia and rigidity that result from high levels of social complexity (Biggs et al. 2010).  What Tainter exposes is the mechanism for the increase in social complexity.  Social complexity results from the accumulation of incremental solutions to the problems that society identifies.  Such complexity may interact with external and internal shocks of either social or biophysical origin to either cause collapse or to generate adaptive reorganization.


Biggs, R., F. R. Westley, and S. R. Carpenter. 2010. Navigating the back loop: fostering social innovation and transformation in ecosystem management. Ecology and Society 15:Article 9.

Tainter, J. A. 1988. The collapse of complex societies. Cambridge University Press, New York.

Tainter, J. A. 2006. Social complexity and sustainability. Ecological Complexity 3:91-103.

Sunday, May 12, 2013

Myth and Memory of Rivers and Shorelines

One of the first things I experienced when learning how to get around Baltimore was the mash up of its multiple street grids.  First I have to admit that most of old Baltimore streets are laid out in a grid pattern, with right angle intersections.  So Baltimore reflects a Renaissance or Enlightenment rational street pattern by and large.  This is a contrast to the famous Medieval and cow-path arrangement Boston is said to exhibit.  Of course Baltimore does have its radial streets that reflect old farm market roads.  And the northwest ray of Reisterstown Road has the hallmarks of an even earlier Native American path that would have followed the high ground of the watershed ridge between the Gwynns Falls and the Jones Falls drainage basins.  But fundamentally, getting around old Baltimore is a matter of navigating a checkerboard of square blocks.  

Baltimore's Grids

Actually, it’s a matter of navigating several different checkerboards that meet at odd angles. Why doesn’t Baltimore have just ONE street grid.  It is clear that the early layouts of Baltimore weren’t worried about following topography, with the exception of some of those radial roads.  Such willful application of the rationalist grid ignores the rolling hills and the occasional valleys of a location that straddles the Coastal Plain and Piedmont geomorphic provinces.  Attemps from the early 20th century on have only partially obliterated the clash of grids in Baltimore.  But the question remains: “Why several grids rather than one grid?”

1864 Baltimore. 
Baltimore has several grids because each of them was oriented to a different shoreline.  Baltimore’s original shoreline was extremely heterogeneous.  In the territory that would become the city, three major streams came down to the harbor in three separate valleys.  The larger Patapsco River entered the Harbor from the west, and established its own complex shoreline patterns.  Jones Falls entered the Harbor as a marshy estuary which extended well upstream.  The grid of Little Italy is anchored to the old edge of Jones Falls.  So too, farther upstream, is the northwest angled grid that incorporates such neighborhoods as Bolton Hill, Penn North, and Druid Heights.  This anchoring is likely a reflection of the importance of the water powered industry along the Jones Falls.

Anchoring Grids

The anchoring of grids along diverse stream and harbor shores is a physical memory of the intersection of water and land.  But the physical nature of that intersection is affected by how people think about shores.  In other words, there are perceptions that might be called the mythology of shores.  Grace Brush earlier in this Web Log (, noted that the original shore lines of streams and estuaries would have included extensive marshes and forested wetlands.  Along streams, peripatetic populations of beaver would have created shifting mosaics of wetlands, pools, and dams as a result of their feeding and denning.  Shores not engineered by people are ragged in outline and mucky.  Tidal action in the coastal marshes would have made a habitat unsuitable for trees, and have maintained broad areas dominated by grasses and sedges, and would have made excellent habitat for larval fish and crabs.

1792 Shoreline in blue, today in green.
Baltimore Watershed Partnership
The historical reality and ecological complexity of unsettled shorelines are not the way that people represent or, in fact inhabit, shores.  A comparison of the map of the coast around Baltimore with a less urbanized shoreline elsewhere on the Chesapeake Bay reveals the power of our shore mythology.  Baltimore’s shore has largely been straightened to accommodate the piers required by industry and shipping, promenades for people, the waterfront condos of the wealthy, and the bars and restaurants overlooking the harbor enjoyed by tourists and residents.  Even in residential suburbs abutting the water, marshes and riparian forests have been replaced by gently sloping lawns of introduced turfgrass.  But beyond the urban and the urbanized outposts of wealth, the maps reveal shorelines of streams and the Bay that are jagged, wrinkled lines.  On the ground, muck and wet soils, marsh plants, or riparian trees that are adapted to wet soils having low levels of oxygen, form the suture between land and water.  These sutures are hybrid habitats that are in no way well represented by the boundary lines that people so readily draw at the edges of their towns and cities.

Using the history of Philadelphia’s establishment and growth, Dilip da Cunha ( has shown how people mythologize city streams and rivers.  Philadelphia is famously taken as an ideal of the gridded colonial city, rationally housing the centers of power and opportunities for settlement, and the relationship to defining features.  Philadelphia is said to be centered on city hall, and its grid fits the – supposedly straight – frame of the Schuylkill and Delaware Rivers.  da Cunha shows that it was in fact the rivers that were the first anchors of Philadelphia.  Even here, though, the relationship of the rivers was simplified – mythologized – into straight lines.

The Mythology of Straight Shores

The Rockland millrace, Pennsylvania.
The current reality of city shores is, however, often a series of straight lines. Think of the Embankment along London’s Thames, the sea wall in Sydney, or Louisville’s cobblestone wharf dating from the days of steamboats.  In many cases, such straight lines are not merely a matter of controlling flooding from upstream, or of mowing grass or cutting trees.  But in most cases, urban shorelines are now literally constructed features.  Millraces and dams on creeks and large streams have existed since the early industrial revolution as constructed linear features that alter the relationship of water to shore.  More extensive shore features such as Baltimore’s piers and docks are also constructed.  A great deal of Baltimore’s current shoreline is the result of filling and draining.  After the Great Fire of 1904, for example, the rubble from clearing the debris from the 64 acre conflagration was used as fill along the Harbor.  The myth and the reality become congruence.  Then the reality reinforces the myth.

So neither in Baltimore, Philadelphia, nor any other river or shore city, are straight lines reflective of the form of the rivers that first invited settlement.  All have lost curvy, swampy or marshy, productive and protective shorelines.  And we have lost the public understanding that land and water have a sloshy, fluctuating and porous relationship.  The sea level rise occasioned by climate change, the retreat of waters during drought, the upland flooding from hurricane rains, and the inundation by coastal storm surges are all reminders that land and water still have a relationship of flux, in spite of the linear tendencies of our clashing grids.