Pleistocene rewilding
With the loss of large herbivores and predator species, niches important for ecosystem functioning were left unoccupied.
[2] In the words of the biologist Tim Flannery, "ever since the extinction of the megafauna 13,000 years ago, the continent has had a seriously unbalanced fauna".
[3] Paul S. Martin (originator of the Pleistocene overkill hypothesis[4]) states that present ecological communities in North America do not function appropriately in the absence of megafauna, because much of the native flora and fauna evolved under the influence of large mammals.
Communities where species evolved in response to Pleistocene megafauna (but now lack large mammals) may be in danger of collapse.
[10] Sergey Zimov, a Russian scientist and proponent of Pleistocene rewilding, argues that it could restore the mammoth steppe ecosystem and thus slow the melting of the Arctic permafrost and give the world more time to respond to climate change.
The main criticism of the Pleistocene rewilding is that it is unrealistic to assume that communities today are functionally similar to their state 10,000 years ago.
Opponents argue that there has been more than enough time for communities to evolve in the absence of megafauna, and thus the reintroduction of large mammals could thwart ecosystem dynamics and possibly cause collapse.
Under this argument, the prospective taxa for reintroduction are considered exotic and could potentially harm natives of North America through invasion, disease, or other factors.
[15] This plan was considered by Josh Donlan and Jens-C. Svenning, and involves (as in rewilding North America) creating a Pleistocene habitat in portions of Europe.
[citation needed] Incidentally, an independent "Rewilding Europe" initiative was established in the Netherlands in 2011, with the western Iberian Peninsula, Velebit, the Danube delta and the eastern and southern Carpathians as particular targets.
In 1988, researcher Sergey Zimov created Pleistocene Park – a nature reserve in northeastern Siberia for full-scale megafauna rewilding.
[24] Reindeer, Siberian roe deer and moose were already present; Yakutian horses, muskox, Altai wapiti and wisent were reintroduced.
The plains bison has made a recovery in many regions of its former range, and is involved in several local rewilding projects across the Midwestern United States.
Mountain goats are already being introduced to areas formerly occupied by Oreamnos haringtoni, a more southern relative that went extinct at the end of the Pleistocene.
Horses originated in North America and spread to Asia via the Ice Age land bridge, but became extinct in their evolutionary homeland alongside the mammoth and ground sloth.
Although small in numbers, there are feral or semi-feral camelids in North America such as Dromedary in Texas and its vicinity[36][37] and llamas among Hoh Rainforest on the Olympic Peninsula.
During the Pleistocene, large populations of Proboscideans lived in North America, such as the Woolly, Columbian and Pygmy mammoths, and the American mastodon.
It now resides only in tropical southeastern Asia, but the fossil record shows that it was much more widespread, living in temperate northern China as well as the Middle East (an area bearing an ecological similarity to the southern and central United States).
Some carnivores and omnivores survived the end of the Pleistocene era and were widespread in North America until Europeans arrived, such as grizzly bears, cougars, jaguars, grey and red wolves, bobcats, and coyotes.
He suggested the introduction of elephants (and other analogues for extinct megafauna) to private lands in the Brazilian Cerrado and other parts of the Americas.
The grazing habits of these tortoises control and reduce the spread of invasive plants, and promote the growth of native flora.
