Friday, November 5, 2010
Can ecosystem engineering prevent ecological catastrophe?
For over a decade, University of Arizona ecologist Michael Rosenzweig has preached a gospel of what he calls reconciliation ecology: designing everyday landscapes to support as many plants and animals as possible.
He says it’s the only way of averting ecological catastrophe, which standard approaches to preserving nature will only slow. Some conservationists have embraced the idea. Others think it’s rose-tinted dreaming. With a computer program directing the design, reconciliation ecology will get its test in Tucson, Arizona.
“We decided to turn Tucson into a lab of a million people,” said Rosenzweig, who spoke on reconciliation ecology Aug. 3 at the Ecological Society of America meeting in Pittsburgh. “We’re not trying to restore old habitats. We’re trying to invent new ones.”
The project’s roots extend back to 1995, when Rosenzweig wrote a textbook on island biogeography, a field of research describing ecological dynamics on ocean islands. Over the last several decades, the research had been applied to terrestrial islands formed by human development. The findings were discouraging. Ecologists predicted the loss of 40 to 50 percent of all species. After reviewing the literature, Rosenzweig thought they were optimistic. He put the figure at 90 percent.
More island-like preserves and parks wouldn’t fix this, he reasoned. It required a “reconciliation” with nature inside human-dominated biomes that were largely ignored by conservationists, and cover almost every piece of non-tundra, non-desert land.
Rosenzweig pointed to piecemeal examples of this approach, like ecosystems flourishing amidst shade-grown coffee canopies, or the wetlands of southern Czechoslovakia’s fish farms. The strategy took shape in his 2003 Win-Win Ecology: How The Earth’s Species Can Survive In The Midst of Human Enterprise.
Reviews were mixed. There wasn’t much doubt about Rosenzeig’s diagnosis, but his solution was questioned. Wrote then-Conservation International ecologist Thomas Brooks in a review, “I genuinely fear that Michael Rosenzweig’s theories and examples are less broadly applicable than he argues. And yet I want to believe that he is right.”
In the intervening years, Rosenzweig hasn’t backed down. “The attitude we’ve had for 100 years is, let’s save habitats. We’ll have remnant patches and call them national parks and wildlife refuges. That slows extinction down, but it doesn’t change the endpoint,” he said. Mass extinctions won’t be avoided “unless we turn our attention to the habitats we haven’t paid attention to, that we haven’t even called habitats.”
In Tucson, those ignored habitats are backyards, schoolyards and the mosaic of neighbourhoods and businesses typical of America’s suburban sprawl. Rosenzweig wants to arrange their habitats with a program built on a database of life-history characteristics on 300 local plant species, plus natural history records gathered from a century of research on Tumamoc Hill, an 870-acre island of relatively undisturbed desert west of downtown.
People can decide what species they want to have. The algorithms tell them what other species they’ll need. “It calculates what the relationships are, and which need to be maintained in order for species of interest to live,” said Rosenzweig. Calculations are modified according to local soil type and topography.
Rosenzweig plans to do an “alpha test” at sites on Tumamoc Hill. Another is now taking place in the Barrio Kroeger Lane, a poor neighbourhood set in the Santa Cruz River floodplain. Native, rainwater-harvesting Sonoran Desert vegetation is being planted to lessen summer floods. It should also bring back four local hummingbird species.
If that works, other Tucson neighbourhoods could follow suit.
“There is so much potential to harmonise people and nature” in this approach, wrote ecologist Gretchen Daily in an email. As head of Stanford University’s conservation biology centre, she studies how to predict ecological changes in human-directed landscapes, a research branch known as “countryside biogeography.”
“There is a fair amount of scepticism about reconciliation being a viable model, which is why this is an important experiment,” said Madhu Khatti, an urban ecologist at California State University, Fresno.
Rosenzweig envisions the tested program becoming a tool for developers, neighborhood associations, businesses, anybody with a backyard -- first in Tucson, then elsewhere, as other ecologists localise the code.
“I can’t put out a general rule to fit every toon, but I can put out a general method, and program it,” he said. “That’s what we’ve done. This has to be done for every area.”
Of course, computer-aided ecosystem design is far from what John Muir or Edward Abbey had in mind, and old-fashioned preserves are needed for true wilderness. But as Khatti noted, “there’s very few places in the world where humans can be completely removed.”
“If you produce an ecological theatre that meets the animals halfway, they’ll do the rest,” said Rosenzweig.
Text by Brandon Keim, 16 August 2010.