Stability and balance decrease ecosystem resilience

Stability is something nearly all managers seek.  We want systems which perk along reliably, doing what we want them to do.

Balance is something most of us strive for in our lives, our work, our relationships.

Unstable, unbalanced people are usually to be avoided.

We are attracted to concepts like balance of nature and climax communities because they tell us that balance and stability are good and natural in the world and its ecosystems.  These concepts continue to be popular though abandoned by ecologists in favor of chaos theory and, more recently, complex adaptive systems theory.

Before the concepts of balance of nature and climax communities were discredited in ecology, some eminent ecologists such as Howard Odum viewed the mature climax community, e.g. an oak-hickory forest in the American Midwest, as a steady-state system which is far more sustainable than a growth-oriented ecosystem[1].  Many modern agroecologists seem to also see the most sustainable system as a well-developed, stable, mature system which recovers from disturbance and adapts to change.[2]

This view of sustainability and resilience does not encompass the fact that all ecosystems have adaptive cycles characterized by phases of rapid growth, mature stability, release and disorganization, and reassembly and reorganization leading back to rapid growth, stability, release and reassembly ad infinitum.

In fact, stability undermines ecological resilience.  This was learned early in forest management.   A stable, mature forest in which fires are suppressed will eventually become a raging inferno which scours the landscape.  The result is often massive erosion and destruction of seeds and roots.  Enforced stability of the forest results in reduced capacity of the system to regenerate.  An unstable, more chaotic ecosystem, with small fires and other disturbances occurring every year, maintains a variety of systems from meadow to savanna to forest.  Disturbance is required to maintain the diversity needed for resilience.

Every system has a temporal dimension which requires both phases of rapid growth and phases of disassembly.  The mature forest seen as a natural climax community by early ecologists and held up today as a model for sustainable systems by some agroecologists was known by both aboriginal Americans and Australians to be a much less productive phase than the grasslands and savannas which precede it.  Consequently they each regularly burned their landscapes creating more open areas for pasture and deeper soils through the incorporation of manure from the increased populations of ruminants. Disruption and disassembly is required to induce a new growth phase.  These ecosystems, temporally composed of a series of growth and disassembly-release phases, may actually be more productive, increase soil quality and water conservation capacity, and store more carbon than systems permitted to progress to steady-state maturation.  Aborigines found that the technology of fire enabled them to maintain their ecosystem predominately in a growth phase.

Today’s ecosystem managers are similarly using technology to continue rapid growth phases instead of settling for mature, steady-state phases.  However, these technologies often destroy resources (soil and water) instead of enhancing them as the system converts the increased productivity into extracted profit.

The conventional wisdom in many sustainability circles that stability and balance are good and growth is problematic should be leavened with the reality of ecosystems.  In fact, trying to maintain stability and a particular type of agroecosystem may actually erode resilience.  By keeping one particular system stable, the resilience of the larger system may crash.  U.S. agricultural commodity policy–promoting stability while decreasing diversity, redundancy and flexibility—is widely believed to undermine ecological resilience of our agricultural system.[3]

Ecological resilience, however, is not resilience in the sense used in most sustainable agriculture circles.  Resilience in sustainability circles is often the materials science sense is the ability to bounce back from disturbance and maintain key functions and components.  In that sense our commodity production system is very resilient.  By maintaining commodity support payments through effective lobbying efforts, the system continues to bounce back and retain all its key functions and components.

As resilience becomes more widely bandied about, we can be sure the materials science definition of resilience will be most attractive for those trying to uphold the status quo—just as ag administrators in the early 1990s declared that “everything our college does is sustainable agriculture.”

Some sustainable agriculture advocates are also intent on preserving particular practices and systems.  As such advocates become more familiar with adaptive cycles and ecosystem resilience, they may embrace the creative destruction at the heart of all resilient ecosystems.  If we cast off the normative proscriptions often attached to sustainability, we’ll be able to see our agroecosystems more clearly.



[2] Gliessman, S., 2004. Agroecology and Agroecosystems.  In Agroecosystems Analysis, http://www.canunite.org/sites/default/files/agroecology%20and%20agroecosystems2004.pdf

[3] Berardi, et al., 2011. Stability, sustainability, and catastrophe. Human Ecology Review, 18: 115-125.

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