Nature’s limits

Contributor: Paul Basken

The gorgeous red tomatoes, piled high in the hot West African sunshine, suggested a huge success.

Just two years after the region’s economically vital crop was decimated by a fly-borne virus, university experts found a gene that conferred resistance and bred it into the tomato seeds.

The science was so efficient that the tomatoes quickly overwhelmed the local canning facility in Mali’s capital, Bamako. But in the same two years, European buyers found other providers. Mounds of tomatoes, and with them the labor of numerous poor African villagers, sat and rotted.

“At that point in 2007,” says one of the researchers, Molly Miller Jahn, then with Cornell University and now a professor of agronomy at the University of Wisconsin at Madison, “I just said, I am never doing this again.”

By failing to take full account of all aspects of what the community and its crop needed to rebound—to be “resilient”—the researchers and their U.S.-government sponsors failed the people they had come to help, Jahn says.

Michael R. Springborn has seen the ways that diverse factors affect resilience. An assistant professor of environmental science and policy at the University of California at Davis, he works on helping to save the chinook salmon that spawn in the Sacramento River before heading out to the ocean.

He has found that strategies that help the most salmon arrive at the ocean during optimal feeding conditions can give the population a sharp boost. But helping to space their arrival may be the better long-term strategy for ensuring a resilient population, given the likelihood of seasonal variations in those optimal conditions.

Stephen R. Palumbi, a professor of biology at Stanford University, is trying to find the key to resilience of coral threatened by a warming Pacific Ocean. A crucial breeding ground at the bottom of the food chain for fish and other species, coral is dying off at alarming rates, but a patch in American Samoa is faring surprisingly well. The key to its resilience may be genetic, says Palumbi, which raises hopes that traits found in the Samoan reef could be incorporated into other corals.

Forty years after the ecologist C.S. Holling coined the term “resilience,” the concept appears to have its most solid grounding in his discipline. Ecologists looking for the best way to manage natural resources have adopted Holling’s notion that they should develop and encourage systems that, in his words, “can absorb and accommodate future events in whatever unexpected form they may take.”

To do that, they attempt to keep options open, view ecosystems in the context of their regions, and emphasize variability.

Agriculture in the United States provides good examples, says F. Stuart Chapin III, a professor emeritus of ecology at the University of Alaska at Fairbanks. Much of the corn and wheat planted domestically has been bred for maximum efficiency in terms of grain volume, water use, and disease resistance. That, however, leaves the crops with little natural variability, meaning a new design is needed each time a pest finds a way to break through the genetic defenses, Chapin says.

“So they’re always sort of working against the laws of nature,” he says.

There is, of course, a belief that the natural world knows best what it needs, and that people shouldn’t be trying to shape it at all. As such, theories that value resilience automatically have at least one fundamentally subjective component: Researchers and policy makers generally don’t see the earth that predates humans as an optimal original state. “Obviously the best thing for the environment is to kill ourselves,” Jahn says.

With that option ruled out, resilience theory can be seen as a modern chapter in the continuing attempt by humans to better understand and preserve the world around them—especially the parts they need to keep themselves alive and healthy.

The value of studying resilience includes figuring out why some things keep functioning under certain stresses and others do not. That kind of approach can help policy makers understand which environmental stresses are most important to avoid; what characteristics are especially important to maintain, encourage, or incorporate into a system; and what systems should get priority in efforts to save them.

For coral, Palumbi is pushing ecologists to help him create a “resilience map,” identifying exactly what species of coral and in what locations fare best in the face of warming ocean temperatures. Realizing that climate change may not be stopped soon, he says, ecologists are transplanting coral from locations outside American Samoa into the more resilient variety found there.

The mapping process might help those researchers identify the genes and molecular processes that could help coral survive longer. One component of resilience suggested by the coral, Palumbi says, is the possibility that organisms have genes with functions that are hidden, and are expressed only when a need for them arises.

Even if scientists can’t help more coral survive, the resilience map could help set priorities for preservation efforts, like blocking construction projects or other activities that might damage the most resilient coral.

“These really robust and resilient corals are still in danger from all kinds of other things” beyond climate change, Palumbi says. “The most heat-resistant coral is still not resilient to bulldozers, for example.”

But even ecologists have some disagreement over the term. Holling has emphasized the idea of a “tipping point” beyond which a system is irreversibly changed—its new state being defined as resilient regardless of whether the change is positive or negative from the human perspective. The fertile soil that follows a volcanic eruption is fortuitous, for example, but the persistent, hypoxic dead zone at the mouth of the Mississippi River is also “resilient.” Others have defined resilience as a measurement of how long it takes a system to return to its original state—the more quickly it does, the more resilient it is.

Holling’s tipping-point concept is “a very dangerous notion,” says Stuart L. Pimm, a professor of conservation ecology at Duke University. That’s because it suggests—especially to policy makers—that scientists can calculate a point up to which human effects like pollution are fully reversible, he says.

Others aren’t sure the term “resilience” adds any real heft to existing methodological approaches. Richard J.T. Klein, a senior research fellow at the Stockholm Environment Institute specializing in climate change, says he prefers to think of the “vulnerability” of people, communities, infrastructure, and human activities to temperature and other climatic variations. Considerations of “resilience” don’t seem useful without any proven strategies for enhancing it, he says.

“‘Resilience’ is a poorly defined flavor-of-the-month kind of term with a cuddly feel-good factor that development and research funders happen to like,” Klein says.

After he pointed out in a 2003 article that cities like New Orleans or New York, while showing resilience following hurricanes, are no less exposed to a repeat disaster, some of the theory’s defenders answered him by saying that resilience means other things, like learning and adapting.

“So it seems like the definition of resilience changes every month or every few months, depending on what else needs to be considered,” he wrote. “It sort of becomes the catchword for everything that’s good.” (See related article, Page B16.)

Even the researchers who helped generate the piles of tomatoes in Mali don’t agree on what resilience means to the affected local farmers. Robert L. Gilbertson, a professor of plant pathology at the University of California at Davis who battled the fly-borne virus, says any problems with the overproduction described by Jahn were minor compared with the overall benefits.

Mali’s farmers certainly face more complications than squelching a virus, Gilbertson says, including a long-running regional competition involving other West African tomato producers, and now the war involving Islamists in northern Mali. But the increased production has let many Malian farmers feed their families, buy new equipment, and send their children to school, he notes.

“This overproduction situation was a blip in the overall progress toward food security,” Gilbertson says.

Much work remains to take resilience from theory to practice. “Research on resilience, especially in the social-ecological context, has been fairly theoretical,” Chapin says.

That doesn’t discount the need to keep trying, says Christo Fabricius, a professor of environmental science at Nelson Mandela Metropolitan University, in South Africa. The earth’s natural resources are being pushed to the absolute limit by a combination of carbon emissions, overconsumption, and population growth, says Fabricius, a leader, along with Holling, in the Resilience Alliance, an international network of universities and governmental and nongovernmental agencies.

“The way we learn to interact with the natural resources of our planet, and our ability to regulate these three factors over the next decade,” he says, “will be the key to both our resilience and that of our planet’s natural systems.”

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