Due to the current shortage of mammoths, Sergey also periodically takes matters into his own hands: He drives his Soviet [era] personnel carrier, which he describes as the equivalent to two male mammoths, through the forest. His only complaint about this substitution is that it does not produce any excrement, an essential component.—joint blog post for the NSF-funded Polaris Project by Anya Suslova, student, Yakutsk State University; and Tyler Llewellyn, student, Western Washington University. (Max Holmes, Woods Hole, PI.)
During the Pleistocene Epoch between about 10,000 and 2,000,000 years ago, nearly half the world’s land mass was covered with tundra-steppe, a cold, dry grassland spanning the distance between forest and desert ecosystems. In these grasslands lived large herbivore populations—mammoth, bison, and musk oxen. These behemoths naturally maintained the landscape through grazing, fertilizing, and tilling the soil with their hooves.
But as the Pleistocene reached its end, the animals died off and less productive forest ecosystems took hold. Scientists have long maintained that climate change caused the die-off, but Russian scientist Sergey Zimov believes otherwise.
Sergey Zimov, who founded and directs the Northeast Science Station in Cherskiy in northeastern Siberia, believes the animals were overhunted, which led to extinction. Just as human actions may be responsible for the steppe transformation, Zimov hopes human actions will return the landscape to its prehistoric state.
Specifically, since 1989 he has worked to restore the grassland ecosystem that existed in Siberia during the Pleistocene by eradicating larch trees and reintroducing the animals that thrived during Pleistocene time. Zimov hopes to transform more than 40,000 acres of forest and shrub land along the Kolyma River to grassland steppe.
Located 25 miles from the Northeast Science Station and surrounded by 150,000 acres of Siberian wilderness, Pleistocene Park is accessible only by boat in summer and snow vehicles in winter. The limited Park infrastructure includes a small cabin that houses two caretakers, a couple of storage outbuildings, and a personnel carrier.
A potential benefit of grassland restoration across northern Siberia, Zimov says, is that it could prevent permafrost from thawing and the subsequent release of stored carbon dioxide, a primary greenhouse gas, due to a warming climate. To help test this hypothesis at Pleistocene Park, Zimov constructed a 105-foot tower with instrumentation that takes constant methane, carbon dioxide, and water vapor readings. In addition to Zimov’s own database, readings are fed into a global CO2 monitoring system maintained by the National Oceanic and Atmospheric Administration.
“Preventing this [global warming] scenario from happening could be facilitated by restoring Pleistocene-like conditions in which grasses and their root systems stabilize the soil. The albedo—or ability to reflect incoming sunlight skyward—of such ecosystems is high, so warming from solar radiation also is reduced,” Zimov wrote in a 2005 essay. “And with lots of herbivores present, much of the wintertime snow would be trampled, exposing the ground to colder temperatures that prevent ice from melting. All of this suggests that reconstructed grassland ecosystems, such as the ones we are working on in Pleistocene Park, could prevent permafrost from thawing and thereby mitigate some negative consequences of climate warming.”
It’s a gargantuan task. Using controlled burns and targeted bulldozing (simulating mammoths), Zimov clears larch trees and willow shrubs. The labor-intensive process allows sunlight and rainfall to reach grasses while returning nutrients to the poor soils.
Next come the megafauna – large animals typical of the Pleistocene Epoch. Large herbivores like mammoths, horses, moose, caribou, bison, and musk oxen kept grasslands healthy; when these animals devoured older grasses, new shoots could grow. These mammals deposited tons of dung, naturally fertilizing and reseeding the land throughout the year. They trampled trees and shrubs, stunting their growth, and cold winter months exposed the ground to the cold, which helped keep permafrost frozen.
While some of the animals are extinct, Zimov has found the closest living relative to repopulate his emerging steppe. So far, he has successfully reintroduced small numbers of moose, musk ox, bison and Yakutian horses, a small, native breed well-adapted to harsh Siberian winters with the ability to locate vegetation under deep snow. Smaller mammals including hares, marmots, and squirrels have also been introduced.
Once populations stabilize, Zimov plans to bring in predators like wolves, bear, larynxes, and polar foxes to keep herbivore populations in check. Once the Park reaches proper animal densities, Zimov expects the ecosystem will maintain itself and flourish; the Russian will then begin expanding the park boundary.—Marcy Davis