Pleistocene Park
Pleistocene Park () is a nature reserve on the Kolyma River south of Chersky in the Sakha Republic, Russia, in northeastern Siberia, where an attempt is being made to re-create the northern subarctic steppe grassland ecosystem that flourished in the area during the last glacial period. The project is being led by Russian scientists Sergey Zimov and Nikita Zimov, testing the hypothesis that repopulating with large herbivores (and predators) can restore rich grasslands ecosystems, as expected if overhunting, and not climate change, was primarily responsible for the extinction of wildlife and the disappearance of the grasslands at the  end of the Pleistocene epoch. The aim of the project is to research the climatic effects of the expected changes in the ecosystem. Here the hypothesis is that the change from tundra to grassland will result in a raised ratio of energy emission to energy absorption of the area, leading to less thawing of permafrost and thereby less emission of greenhouse gases. It is also thought that removal of snow by large herbivores will further reduce the permafrost's insulation. To study this, large herbivores have been released, and their effect on the local fauna is being monitored. Preliminary results  point at the ecologically low-grade tundra biome being converted into a productive grassland biome and at the energy emission of the area being raised. Goals. Researching the effects of large herbivores on the arctic tundra/grasslands ecosystem. The primary aim of Pleistocene Park is to recreate the mammoth steppe (ancient taiga/tundra grasslands that were widespread in the region during the last ice age). The key concept is that animals, rather than climate, maintained that ecosystem. Reintroducing large herbivores to Siberia would then initiate a positive feedback loop promoting the reestablishment of grassland ecosystems. This argument is the basis  for rewilding Pleistocene Park's landscape with megafauna that were previously abundant in the area, as evidenced by the fossil record. The grassland-steppe ecosystem that dominated Siberia during the Pleistocene disappeared 10,000 years ago and was replaced by a mossy and forested tundra and taiga ecosystem. Concurrently, most of the large herbivores that roamed Siberia during the Pleistocene have vanished from the region. The mainstream explanation for this used to be that at the beginning of the Holocene the arid steppe climate changed into a humid one, and when the steppe vanished so did the steppe's animals. Sergei  Zimov points out that in contradiction to this scenario: Zimov and colleagues argue for a reversed order of environmental change in the mammoth steppe. Humans, with their constantly improving technology, overhunted the large herbivores and led to their extinction and extirpation. Without herbivores grazing and trampling over the land, mosses, shrubs and trees were able to take over and replace the grassland ecosystem. If the grasslands were destroyed because herbivore populations were decimated by human hunting, then "it stands to reason that those landscapes can be reconstituted by the judicious return of appropriate herbivore communities." Researching the effects of large  herbivores on permafrost and global warming. A secondary aim is to research the climatic effects of the expected changes in the ecosystem. Here the key concept is that some of the effects of the large herbivores, such as eradicating trees and shrubs or trampling snow, will result in a stronger cooling of the ground in the winter, leading to less thawing of permafrost during summer and thereby less emission of greenhouse gases. Permafrost is a large global carbon reservoir that has remained frozen throughout much of the Holocene. Due to recent climate change, the permafrost is beginning to thaw, releasing  stored carbon and forming thermokarst lakes. When the thawed permafrost enters the thermokarst lakes, its carbon is converted into carbon dioxide and methane and released into the atmosphere. Methane is a potent greenhouse gas and the methane emissions from thermokarst lakes have the potential to initiate a positive feedback cycle in which increased atmospheric methane concentrations lead to amplified global climate change, which in turn leads to more permafrost thaw and more methane and carbon dioxide emissions. As the combined carbon stored in the world's permafrost (1670 Gt) equals about twice the amount of the carbon currently released in  the atmosphere (720 Gt), the setting in motion of such a positive feedback cycle could potentially lead to a runaway climate change scenario. Even if the ecological situation of the arctic were as it was 400,000 years ago (i.e., grasslands instead of tundra), a global temperature rise of 1.5 °C (2.7 °F) relative to the pre-industrial level would be enough to start the thawing of permafrost in Siberia. An increased cooling of the ground during winter would raise the current tipping point, potentially delaying such a scenario. Implementation. Background: regional Pleistocene ecoregions. It has been proposed that  the introduction of a variety of large herbivores will recreate their ancient ecological niches in Siberia and regenerate the Pleistocene terrain with its different ecological habitats such as taiga, tundra, steppe and alpine terrain. The main objective, however, is to recreate the extensive grasslands that covered the Beringia region in the late Pleistocene. This form of grassland (also known as mammoth steppe) was inhabited by a diverse set of large and medium herbivores. Back in the Pleistocene the area was populated by many species of grazers that assembled in large herds similar in size to those in Africa and Asia  today. Species that roamed the great grasslands included the woolly mammoth, woolly rhino, steppe wisent, Lena Horse, muskox, and reindeer. Another herbivore that was abundant in this region during the Pleistocene but now faces possible extinction in its remaining habitats is the saiga antelope, which can form massive herds that keep the vegetation down. At the edges of these large stretches of grassland could be found more shrub-like terrain and dry conifer forests (similar to taiga). In this terrain the browsers of the Pleistocene were to be found. This group of megafauna included woolly rhinoceros, moose, wapiti, Yukon wild  ass, and camels. The more mountainous terrain was occupied by several species of mountain-going animals like the snow sheep. During the Pleistocene there was a great variety of carnivorous mammals as well. On the plains there were prides of Beringian cave lion. These large cats were the apex predators of the region, but also shared their habitat with other predators such as grey wolf, cave hyena, "Homotherium", brown bear, wolverine, and Arctic fox, which all occupied a distinct ecological niche essential for the balance of their respective ecosystems. On the edges of the grasslands (in the shrubs and forests ) there were also brown bears, wolverines, cave bears, lynxes, tigers, leopards, and red foxes. The Siberian tiger and Amur leopard occupied the southern part of the steppe biome and surviving populations are still found along the present Russian-Sino border in the Amur and Primorye regions. Proposed procedure. In present-day Siberia only a few of the former species of megafauna are left; and their population density is extremely low, too low to affect the environment. To reach the desired effects, the density has to be raised artificially by fencing in and concentrating the existing large herbivores. A large variety  of species is important as each species affects the environment differently and as the overall stability of the ecosystem increases with the variety of species (compare "Biodiversity and ecological services"). Their numbers will be raised by reintroducing species that became locally extinct (e.g., muskoxen). For species that became completely extinct, suitable replacements will be introduced if possible (e.g., wild Bactrian camels for the extinct Pleistocene camels of the genus Paracamelus). As the number of herbivores increases, the enclosure will be expanded. While this is taking place, the effects will be monitored. This concerns for example the effects on the flora  (are the mosses being replaced by grasses, etc.), the effects on the atmosphere (changes in levels of methane, carbon dioxide, water vapor) and the effects on the permafrost. Finally, once a high density of herbivores over a vast area has been reached, predators larger than the wolves will have to be introduced to keep the megafauna in check. The first grazing experiments began in 1988 at the Northeast Science Station in Chersky with Yakutian horses. In 1996 a 50 ha (125 acre) enclosure was built in Pleistocene Park. As a first step in recreating the ancient landscape, the Yakutian horses  were introduced, as horses had been the most abundant ungulates on the northeastern Siberian mammoth steppe. Of the first 40 horses, 15 were killed by predators and 12 died of eating poisonous plants. More horses were imported, and they learned to cope with the environment. In 2006 approximately 20 horses lived in the park, and by 2007 more horses were being born annually than died. By 2013, the number had risen to about 30. Moose, already present in the region, were also introduced. The effects of large animals (mammoths and wisents) on nature were artificially created by using an engineering  tank and an 8 wheel drive Argo all-terrain vehicle to crush pathways through the willow shrub. Progress and plans. The vegetation in the park started to change. In the areas where the horses grazed, the soil has been compacted and mosses, weeds and willow shrub were replaced by grasses. Flat grassland is now the dominating landscape inside the park. The permafrost was also influenced by the grazers. When air temperature sank to −40 °C (−40 °F) in winter, the temperature of the ground was found to be only –5 °C (+23 °F) under an intact  cover of snow, but −30 °C (−22 °F) where the animals had trampled down the snow. The grazers thus help keep permafrost intact, thereby lessening the amount of methane released by the tundra. In the years 2004–2005 a new fence was erected, creating an enclosure of 16 km (6 sq mi). The new enclosure finally allowed a more rapid development of the project. After the fence was completed, reindeer were brought into the park from herds in the region and are now the most numerous ungulates in the park. To increase moose density in the park, special constructions  were added to the fence in several places that allow animals outside the fenced area to enter the park, while not allowing them to leave. Besides that, wild moose calves were caught in other regions and transported to the park. In 2007 a 32 meter (105 foot) high tower was erected in the park that constantly monitors the levels of methane, carbon dioxide and water vapor in the park's atmosphere. In September 2010, 6 male muskox from Wrangel Island were reintroduced, but 2 muskoxen died in the first months: one from for unknown causes, and the other from infighting  among the muskoxen. Seven months later, in April 2011, 6 Altai wapiti and 5 wisents arrived at the park, the wapiti were from the Altai mountains and the wisents from Prioksko-Terrasny Nature Reserve, near Moscow. The enclosing fence proved too low for the wapiti, and by the end of 2012 all 6 had jumped the fence and run off. In the years 2011–2016 progress slowed down as most energy was put into the construction of a 150 ha (370 ac) branch of Pleistocene Park near the city of Tula in Tula Oblast in Europe, see below ( section). A few  more reindeer and moose were introduced into Pleistocene Park during this time, and a monitoring system for measuring the energy balance (ratio of energy emission and energy absorption) of the pasture was installed. Attention has now been shifted back to the further development of Pleistocene Park. A successful crowdfunding effort in early 2017 provided funding for further animal acquisitions. Later that year 12 domestic yak and 30 domestic sheep were brought to the park. and the introduction of more muskoxen was planned for 2020. For the near future the focus in animal introductions will generally be placed on browsers, not  grazers, i.e., bison, muskoxen, horses, and domestic yaks. Their role in this phase will be to diminish the amount of shrubs and trees and enlarge the grassy areas. Only when these areas have sufficiently increased will grazers like saiga and wild Bactrian camels be introduced. Reception. Controversial aspects. Critics admonish that introducing alien species could damage the fragile ecosystem of the existing tundra. To this criticism Sergey Zimov replied: "Tundra – that is not an ecosystem. Such systems had not existed on the planet [before the disappearance of the megafauna], and there is nothing to cherish in the tundra. Of course , it would be silly to create a desert instead of the tundra, but if the same site would evolve into a steppe, then it certainly would improve the environment. If deer, foxes, bovines were more abundant, nature would only benefit from this. And people too. However, the danger still exists, of course, you have to be very careful. If it is a revival of the steppes, then, for example, small animals are really dangerous to release without control. As for large herbivores – no danger, as they are very easy to remove again." Another point of concern is doubt that the  majority of species can be introduced in such harsh conditions. For example, according to some critics, the Yakutian horses, although they have been living in the park for several generations, would not have survived without human intervention. They normally tolerate –60 °C, but are said to cope poorly with an abundance of snow and possibly would have died of starvation in the first snowy winter. However, horses of much less primitive stock abandoned by the Japanese Army have been living feral on some uninhabited Kuril Islands since 1945. Despite the deep snows (two to three times deeper than in  Yakutia), they have successfully survived all the winters without feeding. And in Pleistocene Park, while some of the Yakutian horses accept supplementary feeding, others keep away and survive on their own. Positive reception. The Zimovs' concept of Pleistocene Park and repopulating the mammoth steppe is listed as one of the “100 most substantive solutions to global warming” by Project Drawdown. The list, encompassing only technologically viable, existing solutions, was compiled by a team of over 200 scholars, scientists, policymakers, business leaders and activists; for each solution the carbon impact through the year 2050, the total and net cost to society , and the total lifetime savings were measured and modelled. In January 2020, a study from the University of Oxford assessed the viability of the park's goals when implemented on a larger scale. It was estimated that if three large-scale experimental areas were set up, each containing 1000 animals and costing 114 million US dollars over a ten year period, that 72,000 metric tons of carbon could be held and generate 360,000 US dollars in carbon revenues. Visitors. The park is a hub for international scientists and students, who come from around the world to conduct their own ecological  research and experiments. The Polaris Project was a yearly visitor from 2009 to 2015, sending American students on excursions to the park each summer. Another group of visitors are journalists. The park is steadily gaining more media attention and while most journalists do not come to the park itself the number of visitors is increasing. In 2016 for example, the park was visited by a filmmaker, two print media (Swiss "24 Heures" and American "The Atlantic"), and two TV broadcasting companies (German "ARD" and American "HBO"). The total of visitors for 2016 (summer months only) was 45. Size and administration . Pleistocene Park is a 160 km scientific nature reserve ("zakaznik") consisting of willow brush, grasslands, swamps, forests and a multitude of lakes. The average temperature in January is about –33 °C and in July +12 °C; annual precipitation is 200–250 mm. Pleistocene Park is owned and administered by a non-profit corporation, the Pleistocene Park Association, consisting of the ecologists from the Northeast Science Station in Chersky and the Grassland Institute in Yakutsk. The present park area was signed over to the association by the state and is exempt from land tax. The reserve is surrounded by a  600 km buffer zone that will be added to the park by the regional government once the animals have successfully established themselves. In July 2015 the was founded, a non-profit organization (registered in Pennsylvania, USA, with 501(c)(3) status) dedicated to acquiring private donations for funding Pleistocene Park. Hitherto Pleistocene Park had been financed solely through the funds of the founders, a practice that grew increasingly insufficient. In 2019 the was founded in Germany by Michael Kurzeja and Bernd Zehentbauer and serves as a bridge between science, politics, companies, and society. It takes care of the project's financing, seeks  donations in kind such as tractors, utility vehicles, and pick-ups to build the park, and funds further research projects with the Max Planck Institute. and are involved as ambassadors. Southern branch of Pleistocene Park: The Wild Field wilderness reserve. In 2012 to 2014 a branch of Pleistocene Park named "Wild Field" (, ) was constructed near the city of Tula in Tula Oblast in the European part of Russia, approximately 250 km (150 mi) south of Moscow. Unlike Pleistocene Park, Wild Field's primary purpose is not scientific research but public outreach, i.e., it will provide a model of what an  unregulated steppe ecosystem looked like before the advent of humans. It is situated near a federal road and a railway station and will be accessible to the general public. Wild Field comprises 300 ha (740 ac) of which 280 ha have been fenced off and stocked with animals. Already present in the park are nine species of large herbivores and one omnivore species: Bashkir horses (a strain of "Equus ferus caballus") from the southern part of the Ural Mountains, Altai maral/Altai wapiti ("Cervus canadensis sibiricus"), Edilbaevskaya sheep (a strain of "Ovis orientalis aries"), roe deer ("Capreolus spec."), Kalmykian cattle  (a strain of "Bos primigenius taurus"), domestic yaks ("Bos mutus grunniens"), wild boar ("Sus scrofa"), one female elk/moose ("Alces alces"), four reindeer ("Rangifer tarandus") and 73 domestic Pridonskaya goats (a strain of "Capra aegagrus hircus").