Wandering through taiga, tromping through thick underbrush of willow and birch in Siberia, it is easy to imagine yourself transported back to the last ice age. Bison could be browsing over the next hill; cave lions napping across the river. The Arctic feels wild and untamed, even though humans have left indelible marks on the landscape.
Northeast Siberia is a historically important place - infamous during the Soviet Era, home to gold-mining industries and gulags. Scientists now study the Kolyma because of a much more distant past, however. During the Pleistocene, too little snow fell in the region to accumulate ice sheets. The Kolyma remained largely unglaciated, unlike much of North America and northern Eurasia. Instead, windblown dust deposits accumulated, burying the steppe-tundra ecosystem, and then freezing to form permafrost. Slowly, these deposits, called yedoma, built layers of organic rich permafrost tens or even hundreds of meters thick. They are still there today, storing carbon from 15,000 years ago and more. However, yedoma no longer accumulates. The ecosystem has changed drastically, from grassland to boreal forest. A clue as to why can be found along the eroding Kolyma river bank at Duvannyi Yar.
At Duvannyi Yar, scientists have studied the exposed and thawing permafrost. They’ve found ancient seeds, 30,000 years old, and germinated them in the lab. And anyone can walk along the shore and find bones exposed by slumping permafrost as it degrades and falls into the river. These bones reveal the rich ecosystem that thrived here during the Pleistocene, home to bison and musk ox. Horses and reindeer. Wolves and moose. And, of course, mammoth.
These megafauna roamed the landscape, grazing and fertilizing grasslands. Their high densities prevented trees from encroaching on the steppe tundra from the south by trampling any seedlings. Much as the many grazers of the African savannah maintain that tropical ecosystem, their high-latitude counterparts performed the same function.
Then, humans migrated north and east, eventually reaching the far corners of Eurasia. With them, they brought a wave of localized extinctions (and some not so localized). The great herds of bison and mammoth and horses disappeared from the Kolyma. And with them, the steppe-tundra ecosystem. A recent paper in PNAS describes this process, globally. The dense, diverse populations of large herbivores from yesteryear were fundamental to maintaining open woodlands and grasslands. Remove those species, and the entire landscapes becomes more forested.
However, a few Russian scientists are trying to recreate the steppe-tundra, at a place called Pleistocene Park. They have built fences to hem in their herds. They traveled to the Wrangell Islands for musk ox and western Russia for bison and wapiti (a type of deer). They lured horse herds with salt licks and captured baby moose to release into the park.
And, of course, they have a Soviet-era transporter to knock down trees, in lieu of a mammoth.
It’s all very well to try to re-establish a lost ecosystem, but why? Sure, there is inherent value in “re-wilding”, but there are also more practical reasons. Namely, the steppe-tundra was much better at storing carbon in the ground than the current larch forests of the Kolyma. Forests and mossy tundra that now dominate much of northeastern Siberia insulate the ground. Snow accumulates more easily, and the bitter cold air temperatures do not penetrate as deeply into the permafrost. The permafrost underneath taiga or moist, mossy tundra, while still frozen, is less cold than might have been the case in a steppe-tundra ecosystem. Thus, the permafrost – and the millions of tons of carbon stored within it – can thaw more easily in today’s modern ecosystem than might have been the case if mammoth still walked.
Pleistocene Park and its founder, Sergei Zimov, been featured in a number of recent articles and papers about global extinctions of ice age megafauna. I’ve enjoyed reading journalists’ descriptions of the places I’ve been, and the people we work with, but I think my favorite discussion of Pleistocene Park was in a recent book. Beth Shapiro’s How to Clone a Mammoth discusses the science and ethics of “de-extinction”. We might – emphasis on might – be able to raise some sort of mammoth from the grave, but what happens then? Will it survive? Should it survive? Pleistocene Park is an obvious place where new mammoths might be kept, but that doesn’t mean de-extinction is advisable. Still, I was delighted to scratch the ears of a baby moose while there. I can only imagine what it would have been like to, instead, give a baby mammoth a pat on the head.