Ecological restoration is impossible
Why on earth would an ecologist, much less one employed by the Ecological Society of America, say such a thing? Hundreds, perhaps thousands, of papers and books have been devoted to the subject, not to mention numerous meetings and at least one professional society (the Society for Ecological Restoration International, a partner in ESAâ€™s 2002 and 2007 annual meetings.) The phrase â€œecological restorationâ€ generates 772,000 hits on Google, the phrase â€œecological restoration is impossibleâ€ six. So this would appear to be a minority opinion. But perhaps some explication will produce broader agreement than the current three-quarter million to one ratio would imply.
The problem, as I see it, has elements of both science and semantics. The word restoration itself implies something that modern ecology denies. The American Heritage Dictionary defines â€œrestorationâ€ as â€œthe action of restoring,â€ â€œrestoreâ€ as â€œto bring back into existence or useâ€ or â€œto bring back to an original condition.â€ In recent decades, ecologists have established that ecosystems simply donâ€™t work that way â€“ steady states or equilibria rarely persist for long, and irreversible directional change is the rule, not the exception, in living systems. Further, even if ecosystems could persist in a defined steady state for some length of time, it is not possible in a constantly changing world to recreate and maintain the conditions that produced that steady state in the first place. You canâ€™t get there from here.
Semantic arguments (in contrast to scientific ones, we hope) are often dismissed as â€œjust semantics.â€ But words matter, because they affect how we as scientists think about things and how the general public perceives what we tell them. â€œRestorationâ€ raises important semantic arguments. First (ignoring the science arguments), restoration to what? Humans have modifying ecosystems at least since the dawn of agriculture, and recent evidence indicates that the influence of ancient modifications is still detectable. The more we look, the more we find that pristine ecosystems unmodified by human activity have probably not existed for millennia, so how do we choose the state to which we would restore them? Second, even if viewed in a nuanced way by scientists, I fear the public will take us at our words â€“ if we say we are restoring ecosystems, people will believe that such a thing is possible in principle and maybe will believe that we can actually do so. And neither of these is true, for the scientific reasons stated previously. Words matter.
So if ecological restoration is impossible both scientifically and semantically, how do we talk about whatever it is weâ€™re doing when we try to put back some functions or species that have been altered or lost from an ecosystem? The answer, I propose, is straightforward, albeit challenging. First, we recognize, and make sure we tell the public and policy makers, that there is no balance of nature and no way to â€œrestoreâ€ ecosystems in the popular, dictionary sense. Second, we accept the pervasiveness of human influence on the planet and the fact that that influence is as ancient as it is persistent. Having thus defined the philosophical boundaries of the task, we consciously take on the challenge of globally managing ecosystems â€“ all of them. A few we will choose to keep as free of human influence as possible, both for esthetic reasons and because they provide useful controls for our effects on the rest of the planet. Most we will manage intensively, making explicit choices about the kinds of ecosystem services we need and desire, and making policy decisions accordingly. But we will not assume that we will be able to restore these systems and they will then run themselves without continuing management. Because ecological restoration is impossible, but thoughtful, science-based ecological management is not.
Contributed by Cliff Duke, Director of Science Programs, Ecological Society of America