July 5, 2006

Seeding North America with Large Vertebrates; Erudition #9

Conservationists have been debating about whether or not they know enough to begin rebuilding long-lost ecosystems by replacing extinct large vertebrates with analogues from other areas.

From "Restoring Nature's Backbone" by Henry Nicholls for PLoS Biology:
Rather than trying to simply ring-fence what wildlife remains, conservationists need to be restoring whole ecologies to something of their former glory, says Josh Donlan, an ecologist at Cornell University (Ithaca, New York, United States). Last year, he and a long list of high-profile conservation biologists penned a controversial commentary in Nature in which they laid out the case for rewilding North America seeding the continent with suitable stand-ins for species that went extinct thousands of years ago [2].

Donlan's world would see carefully chosen slivers of North America grazed by giant tortoises, horses, and camels; the stamping ground of elephants in place of five species of mammoth; and African lions in lieu of the extinct American lion that once stalked the continent.

The benefits, they argued, are obvious. It would restore ecological processes that have gone by the wayside, mend broken evolutionary relationships, create a back-up population of some of the planet's most endangered species, and raise huge awareness for the conservation cause. The obstacles are substantial and the risks are not trivial, but we can no longer accept a hands-off approach to wilderness preservation, they wrote of their optimistic vision.

Optimistic is an appropriate term. I can see the attraction of a program like this; conservation biologists are often ignored, and seem to be relegated to passive measures of protection. This seeding method is an active approach, where they can use their knowledge to manipulate ecological systems in order to save certain environments.

But is there enough knowledge of these systems to be able to manipulate these environments effectively? Ecosystems are incredibly complex, and if their data are incomplete, if
one organism or mechanism in the system is missing from ecological models, manipulation enters a dangerous zone.

In other words, do we know enough about nature to rebuild it?

The same question can be asked of drug companies. How many pharmaceuticals are pulled from the market because of unforeseen consequences? And this comes after years of research and testing.

Administering drugs to the body is an inelegant process, like tossing a wrench into a car engine and hoping it will fix itself. I'm exaggerating of course, the body automatically distributes chemicals along certain paths, but the paths themselves are not fully understood.

My point is, there are trillions of chemical factors extant in one human being, and one person's chemical environment is sometimes drastically different from the next.

The same can be said of ecosystems. Each one runs analogous to another in certain ways, with different organisms filling certain niches, but there are certain distinctions that need to be fully understood before administering new organisms that never existed in that particular system before.

All I'm saying is this: Ecologists need to make sure that the African lion is truly analogous to the extinct American lion before the animal is introduced to the North American landscape, and the system that exists now, thousands of years after the American lion's extinction, can support such a predator.


  1. Anonymous10:57 AM

    This reminds me of a debate that has been going on in Europe for some time now. That is the extent to which we can or should try to re-create habitats that would be here without humans managing the landscape? and can we even work out what those habitats would be given the amount of human influence inthe past few thousand years?

  2. David Harmon2:10 PM

    We definitely do not have the knowledge to just toss together a bunch of lifeforms and build an ecosystem -- indeed, that may be flatly impossible.

    But of course, that's not how the original ecosystems were created, is it? It's not that somebody decided "well, this top predator needs some herbivores to eat, and they'll need grass...". Rather, over time, those species which happened to be present, settled into dynamic equilibria stable enough to last at least a few kiloyears. Until a bunch of rapacious ground-apes came slaughtering their way across the continent....

    I'd say the question of knowledge is really irrelevant. This isn't something we can do by precalculation, it takes ongoing effort and monitoring.

    I doubt we have the patience or the humility, to let "our" introduced species settle into an equilibrium, let alone to protect them from the appetites of our own kind.

  3. I agree, Dave. It's a bit egotistical to think that we have the necessary techniques to "heal" lost ecosystems.

    The fruit of the efforts of ecologists are data and eventually knowledge. It takes knowledge to properly monitor anything scientifically, especially an ecosystem. But it is far from the time where we should be shipping megafauna to and fro on a relatively unresearched whim.

    Thanks for commenting.

  4. We don't have the knowledge. Personally, I'm glad we don't have lions or giant man-eating moas in North America. And look at the fuss about re-introducing a few wolves to Yellowstone National Park. The first time a lion ate someone... Besides, they might wipe out the wolves. There aren't a lot of large dog-like predators in Africa. OTOH, a limited lion reserve might be interesting. The real trick would be in re-creating dire wolves.