Sunday, September 12, 2010
I recently attended the Ecological Society of America’s annual meeting in Pittsburgh, where the theme was global warming. Eminent ecologists presented models that projected climate change into a bleak future, where species that require unique habitat may be unable to persist. According to conservation biologist Paul Ehrlich, with an extinction rate 200 times normal expected to continue apace, twenty years from now biodiversity will have plummeted. And fifty years from now—well within our children’s lifespans—life as we know it on our blue-green planet will be immeasurably transformed. That these ideas were being presented at the annual meeting of an organization considered a bastion of scientific integrity, such as ESA, made them all the more sobering.
But as I listened to presentation after presentation, I realized that nobody had made the connection between climate change and wolves. Here’s how this can work: Balanced at the apex of an arch, the keystone locks all the other stones in place. Remove it and the arch collapses. Keystone predators, such as wolves, are similarly structurally critical, holding ecosystems together from the top down in food web relationships called trophic cascades.
Keystone predators control elk numbers and behavior. On the lookout for wolves, wary elk eat more sparingly. This releases shrubs and saplings from browsing pressure, improves habitat for other species, and increases biodiversity. These cascading effects, termed the ecology of fear, are based on powerful evolutionary relationships that were in place until we eliminated large predators in the early part of the twentieth century.
While wolves won’t slow climate change, they certainly can help create ecosystems better able to withstand it. However, trophic cascades have yet to make it into the lexicon of climate change solutions. Could this be because combating climate change with wolves is too implausible or costly? Some ecologists think so. But nearly ninety years ago at least one person was advancing the notion of wolf conservation as a means of creating more stable ecosystems in the face of drought and other ecological stressors. That person was the father of contemporary conservation, Aldo Leopold.
A few years ago, I came upon an obscure journal article by Leopold. Written in 1923 and posthumously published in 1979, “Some Fundamentals of Conservation in the Southwest” reached far beyond the ambit of the known. “Is our climate changing?” he asked in this essay. He suggested that ecological stability “varies inversely with aridity,” and that water, soil, animals, and plants, “bear a delicately balanced interrelation to each other.” He urged scientists to parse out these relationships and managers to apply scientific findings. One decade later in the essay “A Conservationist in Mexico,” he asked, “Would not our rougher mountains be better off and might we not have more normalcy in our deer herds, if we let wolves come back in reasonable numbers?”
These intriguing ideas inspired my PhD research in the northern Rocky Mountains on how wolves affect ecosystems. My data is telling the compelling story of how this essential piece—the keystone predator—indeed touches everything, creating habitat for many more species and more resilient ecosystems.
That predation was integral to healthy ecosystems was a radical notion in the 1920s and 30s, when Westerners and the federal government were hard at work wiping out predators. It’s still radical. Managers during Leopold’s era as well as many managers today focus on habitat and see predators as something to be controlled. Leopold suggested a holistic ecological perspective that can enable us to develop better solutions and more ethical relationships with nature. He believed that these relationships and solutions included wolves.
These arguments are far from settled today. In August 2010 wolves were put back on the endangered species list in the northern Rocky Mountains. Central to the intense tug-of-war over the listing is the definition of a recovered wolf population and how it should be managed. But aside from population issues, we have yet to fully consider keystone effects and how wolves can help restore ecosystems.
I live in the rural West in a place where wolves have returned, and I come from a ranching background. Accordingly, I realize that large carnivore debates will not be resolved easily. As I write this it is late summer. Looking out my window at the flush of growth in our pasture that has arisen since wolves returned to this place, and observing the richness of songbirds perched in what were formerly depauperate knee-high shrubs, I think how splendid and apposite these cascading relationships can be.
Leopold was on the right track. If we are serious about adapting to climate change by creating more resilient ecosystems, turning some of them over to wolves may be the most enlightened course of action.
Cristina Eisenberg is an author, conservation biologist, and Boone and Crockett Fellow who studies how wolves affect forest ecosystems throughout the West.