Wednesday, May 5, 2010

Elephants roaming America? A big idea for rebooting nature

A new theory suggests that the thick forests that we think of as wild may actually be an effect of human settlement.

Image: Evamariakintzel / Wikimedia Commons

By Andrew Curry
From the March 2010 issue; published online for subscribers only on May 5, 2010

On the train headed north from Amsterdam’s Central Station, be sure to sit to the left. Just past the town of Almere, as you round a right-hand bend, you will find a sight unseen in Europe for centuries, if not millennia: hundreds of red deer, plodding groups of long-horned wild cattle, and skittish herds of low-slung brown horses, all moving through the open landscape like something out of a cave painting. This place goes by the name of Oostvaardersplassen. It is a nature reserve, yes, but it is also a far-reaching experiment. Biologists worldwide are increasingly talking about using large herbivores like the ones sharp-eyed passengers can spot from the train to re-create prehistoric, and sometimes even prehuman, ecosystems.

When keystone species—from ancient mammoths, woolly rhinos, and giant bears to more prosaic grazers like bison, horses, and deer—are wiped out, ecosystems that had sustained themselves in perpetuity collapse. The result is a severe loss of biodiversity. By reintroducing approximations of extinct animals to modern habitats, rewilding advocates want to reestablish dynamic systems that have not existed since the rise of human settlement in Europe. This reserve is the first place where they have done more than talk. Just a short train ride from downtown Amsterdam, nearly 3,000 wild horses, deer, and descendants of prehistoric cattle roam a landscape that is being dramatically shaped by their presence.

The brainchild of a pugnacious Dutch ecologist named Frans Vera, Oostvaardersplassen is challenging some of our most basic assumptions about wildness. Today thick, dense forests are considered synonymous with unspoiled nature. “The current idea is that when you have an area and you do nothing with it, it turns into a forest,” Vera says. Ecologists call this one-way process “succession” and say it rules the unfolding of ecosystems much as natural selection rules evolution. The theory has dominated conservation for centuries, virtually unchallenged.

Until now. Vera says his experiment in rewilding has revealed succession as a human artifact: an unnatural, unbalanced outcome created when people killed off the woolly mammoth and corralled wild horses and cattle. Without free-roaming herds of grazing animals to hold them back, closed-canopy forests took over the land wherever humans did not intervene. The result is a crippled collection of ecosystems that need constant human help to limp along. But Oost­vaardersplassen, some 25 years in the making, stands as a test case of what the wild animals that once roamed Europe might create when left to their own devices. …

Elephants Roaming America? A Big Idea for Rebooting Nature

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