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The effects of global warming, habitat loss, and alien species are pushing extinction rates to
new heights (Thomas et al. 2004, Barnosky et al. 2011, Dirzo et al. 2014) and the argument for
re-wilding is strengthened in cases where humans are known to be the major driver of extinc-
tion (Donlan et al. 2006). The palaeoecological record shows that many species survived
warmer conditions in past interglacials and that suitable climate space still exists for many
Pleistocene species, thereby supporting claims that humans were at least in part responsible
for megafaunal extinctions (Koch and Barnosky 2006).
Re-wilding projects range in scope and ambition from full-scale Pleistocene parks, through
woodland restoration projects, to re-introduction of locally extinct species, or the replace-
ment of extinct species with taxon substitutes. Pleistocene parks have been hailed by some as
a vision of bold optimism, in a conservation landscape that is all too often mired in crisis and
reactivity. In Siberia, there is strong evidence that humans played a role in megafaunal extinc-
tions and there is compelling palaeoecological evidence that herbivore extinctions have neg-
atively affected steppe ecosystems, potentially leading to the release of massive amounts of
carbon (Zimov 2005, Zimov et al. 2006). In North America, however, Pleistocene Parks are
more controversial, utilizing combinations of animals from Asian and Africa with no past
analogue and with questionable evolutionary potential. In Europe, a Pleistocene park in the
Netherlands contains mainly domestic animals and no carnivores, necessitating ongoing
intervention by managers.
European woodland restoration is benefitting from a re-wilding approach (Vera 2000). It
seems likely that European 'wildwoods, with dense, closed canopies, may have been a prod-
uct of megafaunal attrition in the early-mid Holocene, and that a more heterogeneous wood-
pasture structure was present in the last interglacial, returning in the late Holocene, when
human management increased the abundance of light demanding plants (Sandom et al.
2014). Therefore, re-wilding of European woodlands with large herbivores like deer, ponies,
wild boar, and ancient breeds of cattle is in accord with conservation and cultural aspirations,
and new opportunities for re-wilding are emerging as marginal farming areas are abandoned
(see Chapter 7).
Islands are special cases for re-wilding, because they have been devastated by extinctions
in historic times, and have many endemic species. Large animals have been lost relatively
recently, so the ecological connections have not had time to diverge through evolution. Fur-
thermore, there is good knowledge of how many island landscapes looked when megafauna
were still around, and palaeoecological records can further inform restoration and re-wilding
initiatives. Palaeoecology can identify the former ranges of currently rare species, guiding
inter-situ conservation efforts that reintroduce species from nearby islands or mainland pop-
ulations (Burney and Burney 2007). In some cases, extinct taxa are being replaced by func-
tional equivalents that restore ecosystem services, and enhance ecological and genetic
connectivity (Hansen 2010). The case for re-wilding with alien species is stronger on islands,
because their high degree of endemicity makes it more likely that functional equivalents will
be needed to restore essential ecological processes like pollination and seed dispersal.
Despite the controversies, there is no question that re-wilding can potentially contribute to
ecological restoration and the provision of ecosystem services, in the process providing
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