Posts Tagged ‘diversity’

Community Resilience, Diversity and Feedback Loops

Tuesday, July 10th, 2012

This is the second in a series of three articles on community resilience and building a sustainable economy (first article, third article). It is a modified version of an article originally appearing in my syndicated newspaper column “Your Ecological House.”


What can communities and local governments do to help ensure the well-being of their citizens as we face an uncertain future?

Many communities are discussing “community resilience strategies,” policies and programs that can help them bounce back from “perturbations” (problems) caused by widely anticipated global environmental and economic stress. And it’s a good bet that those communities that actually develop and invest in community resilience strategies will greatly increase their chances of surviving or even prospering in an era of dwindling resources, unpredictable economic fluctuations and rapid climate change.

Community resilience planning (as preparation for environmental and economic emergencies, no ordinary “natural disasters) is a fairly new concept being developed by environmental/economic think tanks such as the Post Carbon Institute ( While the think tanks focus on solutions for human communities and economies — investing in sustainable local businesses, developing community energy systems and so on —  their work is rooted in a decades-old branch of ecology that studies resilience in ecosystems.

In the first article in this series, I discussed how learning about the resilience of natural ecosystems — which have survived and, mostly, thrived on this planet for over three billion years — can inform our own efforts at community resilience planning. I discussed how ecosystems conserve energy through seamless integration with their abiotic (non-living) environment and by closing food loops, thus circulating the solar energy initially captured by plants throughout the system.

While those basic energy-conservation mechanisms — amounting to “reduce, reuse, recycle” in human terms — provide ecosystems with a stable basis for continuance (sustainability), they are not resilience mechanisms as such. However, nature has provided additional mechanisms  — including biological diversity and tight feedback loops — that allow ecosystems to recover from perturbations such as forest fires, eventually returning to their pre-disturbance state.

Species diversity ensures that if the population of an organism such as an insect pollinator that plays a critical role in an ecosystem is greatly reduced or eliminated — victimized, say, by predation, disease or human-made pollution — another pollinator’s numbers will increase to at least partially fill the role of the first. Thus the plants that depend on pollination for reproduction will survive — possibly preventing a general collapse of the ecosystem and eventually allowing it to recover to its previous state of dynamic equilibrium.

But what if there are no “other” pollinators to take the place of the original?

When diversity is reduced in natural or human systems, they become less resilient and more vulnerable to collapse. For example, monocultural farming has repeatedly led to crop failures that can induce famines such as the famous Irish potato famine of the 19th century. Similarly, economic systems dominated by a few “too-big-to-fail” players are far less resilient than economies that distribute wealth among many smaller institutions.

Thus communities are wise to encourage and invest in local diversity, funding or assisting small businesses, family farms and the like wherever they can. It is unwise to “put all your eggs in one basket,” for example by inviting giant corporations into your community, only to watch them pack up and outsource themselves a few years later.

Feedback loops control energy flows and populations in ecosystems and the ecosphere as a whole. Feedback can be accelerating or diminishing (positive or negative), and can destabilize or strengthen a system, depending on their relationship to the system’s components.

If that seems a bit abstract, think of a forest fire as a destructive accelerating feedback event — it feeds on itself until it consumes the forest. In response, forests have evolved resilience mechanisms that involve reseeding themselves after a fire to take advantage of the nutrients left in the fire’s wake.

This process has been termed “creative destruction” — creative in the sense that the destruction allows for new opportunities — for new organisms to thrive that were crowded out by the original, mature forest.

While creative destruction works in nature — which can rise again from the ashes of a former environmental “regime” — the implied sacrifice of the existing order is unacceptable for human civilization.

Therefore part of the challenge of community resilience planning is identifying destructive and affirmative feedback loops, and learning how they affect human “ecosystems”and how we can make them work for us — a critical topic we’ll explore in the next article in this series.