Where The Wild Things Were: Re-wilding and the Sixth Extinction - Biodiversity Conservation and Environmental Change - page 31

forms of re-wilding argues for recreating assemblages of animals and associated vegetation
structures that resemble as far as possible their Pleistocene counterparts (Donlan 2005,
Zimov 2005).
It is argued that re-wilding provides an optimistic conservation agenda that allows locally
extinct species to be returned to their historic range (Donlan et al. 2006). Furthermore, re-
wilding could offer opportunities for restoring ecosystem structure and function by replacing
extinct species with relatives that are functionally equivalent, thereby restoring essential eco-
system services like pollination and seed dispersal (Donlan et al. 2006). Re-wilding is also
controversial, however, with critics arguing that we cannot turn back the clock, and that the
new assemblages created would be 'Frankenstein' ecosystems (Dinerstein and Irvin 2005,
Oliveira‐Santos and Fernandez 2010). Palaeoecology and other long-term data can provide a
window into the effects of extinction and clues as to how landscapes would have looked when
animal populations were still intact. This information is critical to the success and feasibility
of re-wilding plans, offering the opportunity to re-create landscapes that benefit wildlife,
restore ecological health and nurture the love of nature that provides inspiration and solace
to so many people (Monbiot 2013a, b).
Late Quaternary extinctions
In the late quaternary period, between 50,000 and 3,000 years ago, two-thirds of mammal
genera and one-half of megafaunal species—the species that weighed more than 44 kg—
became extinct (Nogués‐Bravo et al. 2010). At the same time, climate changed dramatically
from the cold, arid Pleistocene, to warm interglacial conditions of the Holocene from c. 11,000
years ago. Against the backdrop of environmental change, there is a remarkable co-incidence
between the timing of extinctions and the arrival of modern humans (Koch and Barnosky
2006). Outside of the African continent, most areas have lost their Pleistocene megafauna
(Figure 3.1), and in recent centuries, carnivores and island species have been particularly
hard hit. These large animals are the 'keystone species' that maintain essential ecological
processes and structure biological communities (Ripple and Van Valkenburgh 2010, Galetti
and Dirzo 2013, Seddon et al. 2014). As a result, many present-day ecosystems are likely to be
artefacts of today's impoverished fauna and there are moves to re-wild ecosystems, restoring
both ecological function and the spiritual and aesthetic qualities of wilderness areas, where
wild animals are free to roam. For this to be realistic, we need to understand the causes and
consequences of megafaunal extinctions. A purely climatic explanation for megafaunal losses
might preclude options for ecosystem restoration because environmental conditions are no
longer suitable. On the other hand, an anthropogenic driver of extinction might reinforce the
ethical arguments for re-wilding, while at the same time providing grounds for optimism that
suitable environments could be recreated (Donlan et al. 2006).
The period between 50,000 and 10,000 years ago was a time of rapid climate change when
the earth moved from full glacial conditions of the Pleistocene into the warmer climates of
the Holocene. During this time period, pulses of mega-faunal extinctions took place, in