In September 2018 I had the opportunity to visit Pleistocene Park, and project in the far north-east Siberian Arctic (with my colleagues Marc Macias-Fauria and Paul Jepson), where large wild animals are being introduced in an attempt to shift the existing tundra into an extinct ecosystem, the mammoth steppe.
The landscape of the region is vast and sparsely populated, one of northern taiga larch forests grading into willow tundra, and interspersed with innumerable thermokarst lakes. In September the deciduous larch forests blazed a brilliant gold, framed by red alder and birch understory.
The landscape is littered with relics of the collapse of the Soviet Union, when this remote high Arctic region was heavily depopulated and abandoned.
Our base is the wonderful North East Science Station, sitting on the banks of the river and centred on an abandoned TV satellite station. It provided good food, genial company, bountiful supply of coffee, chocolates (and vodka!), and a sauna by the river bank. On the nights around my birthday the night sky was laced with vast shimmering auroral storms.
At places such as Duvany Yar, the permafrost-frozen river banks erode into the meandering Kolyma River. High banks of carbon-rich yedoma soils are exposed, the result of slow-frozen accumulation of thousands of years of plant productivity.
Walking along the beach, a surprisingly large number of large bones pop out: horse, bison, rhinoceros and mammoth, frozen in the Pleistocene tens of thousands of years ago. From transects of the beach it is possible to work out the density of these numbers, and the numbers are high. The landscape was a northern Serengeti, rich in mammoths, bison, horses, camels bears and lions, all deriving food and nutrition from a highly productive grassland. Yet all this occurred in the high Arctic during the ice ages. How was such a cold climate able to support such high productivity and biomass? The hypothesis underpinning Pleistocene Park is that it was the animals that made the steppe ecosystem, by accelerating the nutrient cycle many hundredfold through eating and egestion.
Pleistocene Park is an attempt to rebuild this lost grassland ecosystem. Sergey and Nikita Zimov have introduced a range of large and cold-tolerant mammals, including horses, yaks, bison, sheep, musk oxen, local reindeer and soon cattle. In fenced patches where the grazing in intense, the system is shifting into a grassy willow savanna. By the lake floodplains are grasslands that provide vital and reliable grazing lands while the system is in transition.
This experiment it not just about animals and ecosystems. A key hypothesis is that the high biomass of animals would have trampled with winter snow layer, preventing it from being an insulating blanket, and thereby freezing the soils deeper in winter. This is turn would reduce the risk and depth of summer melt. As the regional climate warms, this may be a key tool to keep the carbon-rich soils frozen, and thereby preventing a dangerous feedback on climate change.
Thank you to Nikita Zimov and his family and staff for hosting us with endless good humour and many tales. Thanks to the Oxford University John Fell Fund and the School of Geography and the Environment for supporting this visit.
Yadvinder Malhi is an ecosytem ecologist and Professor of Ecosystem Science at Oxford University