Panarchy theory helps us understand how complex systems of all kinds, including social systems, evolve and adapt. Of course, it shares similarities with other theories of adaptation and change. Its core idea-that systems naturally grow, become more brittle, collapse, and then renew themselves in an endless cycle-recurs repeatedly in literature, philosophy, religion, and studies of human history, as well as in the natural and social sciences. But Holling has done much more than just restate this old idea. He has made it far more precise, powerful, and useful by distinguishing between potential, connectivity, and resili­ence; by identifying variations in the system’s pace of change as it moves through its cycle; and by describing the roles of adjacent cycles in the grand hierarchy of cycles.

On the WorldWatch Institute website, Thomas Homer-Dixon presents the ideas of pioneering ecologist Buzz Hollings, the founder of the discipline of panarchy, which studies the growth and collapse patterns of both natural and human systems.

In this excerpt, he presents the paradox of connectivity, while it enhances the efficiency of systems, it undermines their resilience. Think about travel: once the whole world is interconnected, diseases can spread more rapidly. The example given here below concerns forest, but can be applied to society as well. You could call it the dark side of peer to peer, and this is why it should concern us.

During this early phase of growth, the forest ecosystem is steadily accumulating capital. As its total mass grows, so does its quantity of nutrients, along with the amount of information in the genes of its increasingly varied plants and animals. Its organisms are also accumulating mutations in their genes that could be beneficial at some point in the future. And all these changes represent what Holling calls greater “potential” for novel and unexpected developments in the forest’s future.

As the forest’s growth continues, its components become more linked together-the ecosystem’s “connectedness” goes up-and as this happens it evolves more ways of regulating itself and maintaining its stability. The forest develops, for example, a larger number of organisms that “fix” nitrogen-converting the element from its inert form in the air to forms that plants and animals can use-in the specific amounts and in the specific places needed. It becomes home to more worms, beetles, and bacteria that break down the complex organic molecules of rotting plants into useful nutrients. And it produces more negative feedback loops among its various components that keep temperature, rainfall, and chemical concentrations within a range best suited to life in the forest.

Over time as the forest matures and passes into the late part of its growth phase, the mechanisms of self-regulation become highly diverse and finely tuned. Species and organisms are progressively more specialized and efficient in using the energy and nutrients available in their niche. Indeed, the whole forest becomes extremely efficient-in a sense, it effectively adapts to maximize the production of biomass from the flows of sunlight, water, and nutrients it gets from its environment. In the process, redundancies in the forest’s ecological network-like multiple nitrogen fixers-are pruned away. New plants and animals find fewer niches to exploit, so the steady increase in diversity of species and organisms slows and may even decline.

This growth phase can’t go on indefinitely. Holling implies-very much as Tainter argues in his theory-that the forest’s ever-greater connectedness and efficiency eventually produce dim­inishing returns by reducing its capacity to cope with severe outside shocks. Essentially, the ecosystem becomes less resilient. The forest’s interdependent trees, worms, beetles, and the like become so well adapted to a specific range of circumstances-and so well organized as an efficient and productive system-that when a shock pushes the forest far outside that range, it can’t cope. Also, the forest’s high connectedness helps any shock travel faster across the ecosystem. And finally, the forest’s high efficiency makes it harder for it to realize its rising potential for novelty. For instance, the extra nutrients that the forest ecosystem has accumulated aren’t easily available to new species and ecosystem processes because they’re fully expropriated and controlled by existing plants and animals. Overall, then, the forest ecosystem becomes rigid and brittle. It becomes, as Holling says, “an accident waiting to happen.”

So in the late part of the growth phase of any living system like a forest, three things are happening simultaneously: the system’s potential for novelty is increasing, its connectedness and self-regulation are also increasing, but its overall resilience is falling. At this point in the life of a forest, a sudden event such as a windstorm, wildfire, insect outbreak, or drought can trigger the collapse of the whole ecosystem. The results, of course, can be dramatic-large tracts of beautiful forest can be obliterated. The ecosystem loses species and biomass and in the process much of its connectedness and self-regulation.

But the effects on the ecosystem’s overall health may be very positive. A wildfire in a mature forest creates open spaces that allow new species to establish themselves and propagate; it destroys infestations of disease and insects; and it converts vegetation and accumulated debris into nutrients that can be used by plants and animals that reestablish themselves after the fire. The organisms that survive become much less dependent on specific, long-established relationships with each other. Most important, collapse also liberates the ecosystem’s enormous potential for creativity and allows for novel and unpredictable recombination of its elements. It’s as if somebody threw the forest’s remaining plants, animals, nutrients, energy flows, and genetic information into a gigantic mixing bowl and stirred. Once-marginal species can now capture and exploit newly released nutrients, and genetic mutations that were a bane to survival can now be a boon.

And because the system is suddenly far less interconnected and rigid, it’s far more resilient to sudden shock. This is a perfect setting for the forest’s plants and animals to experiment with new behaviors and relationships-a pollinator species like a bee or wasp will try gathering nectar from a type of flower it hadn’t previously visited, or a carnivore might try killing and eating a different kind of prey. If such experiments fail, the damage is less likely to cascade across the entire system.

In these ways the forest ecosystem reorganizes and regenerates itself, quite possibly in a very new form. Put simply, the catastrophe of collapse allows for the birth of something new. And this cycle of growth, collapse, reorganization, and rebirth allows the forest to adapt over the long term to a constantly changing environment. “The adaptive cycle,” Holling writes, “embraces two opposites: growth and stability on one hand, change and variety on the other.” It’s at once conserving and creative-a characteristic of all highly adaptive systems.

Holling and his colleagues use a three-dimensional image to represent the relationship between a system’s rising potential and connectedness and its declining resilience. The shape looks like a distorted figure eight or infinity symbol floating in space. In the foreground is the growth phase-a curve that moves upward as the system’s potential and connectedness increase. At the same time, the curve moves forward in three-dimensional space-toward the observer-as the system’s resilience declines. Holling and his colleagues call this part of the adaptive cycle the “front loop.” It represents a process of incrementally rising complexity. At the top of this curve, the system collapses. Things then happen fast as the system descends into the “back loop,” where it undergoes a rapid process of reorganization before beginning once more the slow process of growth. “