Pleistocene Park

Pleistocene Park

During the last Ice Age, known as the Pleistocene epoch,large herds of herbivores roamed the vast grasslands that covered nearly half the Earth’s land mass.As the woolly mammoths, woolly rhinoceroses, bison, yaks, deer, elk, and musk oxen grazed, they deposited tons of manure, fertilizing and reseeding the soil. These shaggy bulldozers suppressed forests and kept the grasslands open as they trampled trees and shrubs, allowing sunlight and rainfall to reach grasses. In the winter,grazers in search of food dugthrough the insulating snow cover with their hooves, exposing the ground to the cold and helping to keep the permafrost frozen.Wolves and massive cave lions fed on the herbivores and kept their numbers in balance.With the spread of humans, however, with their deadly and efficient hunting technology, these creatures vanished, and with them the grasslands. Trees began to move in.

Today, the plains of northern Siberia still occupy a climate that is optimal for pastoral grassland ecosystems. In the far northeast corner of Eurasia, Russian scientist Sergei Zimov is building a40,000-acre preserve known as Pleistocene Park, working to transform larch forests and willow shrub land to grasslands in order to reestablish the working ecosystem of the mammoth steppe. Zimov is striving to reproduce the conditions of the Pleistocene grasslands, not to copy the details one-to-one but to reestablish the processes and functions that kept the steppes open and the permafrost frozen. The first step has been to reintroduce small herds of musk oxen, bison, deer, and Yakutian horses.Targeted bulldozing with a tank simulates the disturbance that a pair of adult mammoths might have produced. Zimov says, “Today we have no mammoths, so I use a tank” (Wolf 2008, 69). Once herbivore populations become stable and begin to grow, he will reintroduce predators, including foxes, wolves, and Siberian tigers.There may be fluctuations in populations for a time, but eventually it is expected that the ecosystem will be self-maintaining. When the reserve reaches that state, the nonprofit Pleistocene Park foundation will work to expand the park (Davis 2011).

Zimov believes that restoring a stable mammoth steppe ecosystem across northern Siberia could play a significant role in preventing runaway climate catastrophe, bykeeping
500 billion tons of Pleistocene carbon frozen in the permafrost (Wolf 2008, 67). According to Zimov, Siberianpermafrost is among the world’s largest reservoirs of organic carbon, holding 150 percent more carbon than allthe world’srainforests (Zimov 2007, 111). If this permafrost melts it will trigger releases of huge quantities of methane, a greenhouse gas with 25 times the global warming potential of carbon dioxide.

In the summertime, grasslands are light in color and have a much higher albedo than dark forests, keeping the ground cooler.In addition, research shows that what determines the accumulation or thawing of permafrost in the first weeks of spring is whether the grassland surface is blanketed by white snow, or whether black tree trunks reach above the surface, absorbing sunlight (Wolf 2008, 67).In the wintertime, it is actually the absence of snow that helps protect permafrost. Herds of herbivores will trample through the wintertime snow cover, exposing the ground to colder temperatures and preventing the permafrost from melting.

Thus the urgent and primary goal of the work at Pleistocene Park is not just ecosystem restoration but the prevention of runaway global warming. Zimov and his research partners continue to live and work in one of the harshest climates on Earth because they believe that restoring mammoth steppes may offer the best chanceof preventing climate catastrophe.

Sources

Davis, Marcy. “Pleistocene Park.” Field Notes: The Polar Field Services Newsletter,January 18, 2011.

Donlan, C. Josh. “Restoring America’s Big, Wild Animals.” Scientific American, June 2007: 70–77.

Fraser, Caroline. Rewilding the World: Dispatches from the Conservation Revolution, 298–99. New York: Metropolitan Books, 2009.

Wolf, Adam. “The Big Thaw.” Stanford, September/October 2008: 63–69.

Zimov, Sergei. “Pleistocene Park: Return of the Mammoth’s Ecosystem.” Science,vol. 308 (May 6, 2005): 796–98.

Zimov, Sergei. “Mammoth Steppes and Future Climate.” Science in Russia, 2007: 105–12.