Research shows that many lakes can exist in one of two stable states, depending on how much of a chemical called phosphorus is in them.
For humans, the oligotrophic state – in which the water has submerged vegetation and allows swimming and water sports – is the good state.
The eutrophic state – in which nutrients in the water lead to cloudiness and toxic algal blooms – is the bad one. But that’s just from a human perspective. From the perspective of algae, the eutrophic state is good – and it’s stable.
There’s also a brief transitional state between those two. Evidence shows that many other ecosystems also can be described using this three-state classification.
The goal of policy should be to keep the lake in the oligotrophic state for as long as possible or, alternately, to keep this lake in the eutrophic state for as little time as possible.
In other words, policymakers should want the lake to be maximally Holling resilient in the “good” oligotrophic state, and minimally Holling resilient in the “bad” eutrophic state.
Lessons for system management
Here are three key takeaways:
First, the concept of resilience – since it’s integrally tied to the state of a system – can be good or bad. It all depends on the state of the system that a policymaker is seeking to affect.
Second, talking about the Pimm or engineering resilience of the lake is unhelpful because the lake – and many other systems – can exist in more than one stable state. Relatedly, the question of how quickly a shocked system returns to its equilibrium state can’t be answered meaningfully because once the shock is removed, the system may not return to its pre-shocked state.
And finally, keeping our lake in the human-friendly oligotrophic state for as long as possible directly brings time into the management problem. Since sustainable development and sustainability are both about dynamics or phenomena happening over time, there’s a definite connection between resilience and sustainability.
Specifically, the sustainability of a system requires that this system be resilient in the sense of Holling. We could also say that a necessary condition for sustaining a system is that it be resilient. This is also what the researcher Charles Perrings has in mind when he says that a development strategy isn’t sustainable if it isn’t resilient.
Environmental policymakers like to talk about sustainability and resilience. But in my experience, not enough of them know what these words mean. To get better results, they can start by defining their terms.
Amitrajeet A. Batabyal does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
Source: The Conversation