The planet that humans inhabit is changing. Human populations are increasing at an ever quicker rate. Biodiversity is being lost at an ever increasing rate since modern humans evolved; a rate that many argue now exceeds the normal background rate of extinction. The pressures causing much of the declines in biodiversity are increasing. Anthropogenic climate change is overtaking the previously dominant pressures of habitat degradation and fragmentation, pollution and disease. The impacts of climate change are only set to get worse. The current situation of biodiversity loss, known as defaunation requires a call to arms for conservationists.
One method in the conservationists toolbox that some argue can help stem the impending onset of doom outlined above are wildlife translocations. Translocations come in a range of intensities from reinforcement and reintroduction of species within the historic range to assisted colonisation and ecological replacement of species outside of the indigenous range of a species to an area of suitable habitat. The latter two represent conservation introductions and were first proposed in 1985 (Seddon et al, 2014). Conservationists are increasingly considering introductions as many difficulties arise in establishing reintroductions in a rapidly changing world. Not a new concept but one that has recently undergone increasing flare in the media and conservation literature is rewilding. I will illustrate this concept and discuss it as a potentially useful conservation tool
Rewilding encompasses all aspects of translocations. However the main focus is on restoring ecological processes especially with respect to top-down trophic cascades. The Wilderness Act (1964) of the USA is based on a similar “rewilding” philosophy however the original concept of rewilding really came into its’ own in 1991 with Wildlands Network (formerly Wildlands Project). Three key principles outline rewilding; large protected regions, habitat connectivity, bolstering ecosystem processes. Restoration of ecosystem function can increase biodiversity of the restored site by as much as 44% and boost ecosystem services output by as much as 25% (Sandom et al, 2013).
The concept of rewilding is attractive. The journalist George Monbiot has taken a special interest in the rewilding debate. He provides an eloquent manifesto of rewilding and what it means. Individuals have even taken ecosystem restoration into their own hands. Germaine Greer invested in a disused agricultural plot, stripping out invasive flora and replanting only native flora so that the native fauna can eventually takeover to restore a section of long-lost rainforest ecosystem in south-east Queensland.
Numerous rewilding projects have been established across the globe. Wild Europe represents an international level approach to restoring degraded habitats therefore overcoming a problem of piecemeal conservation initiatives at the local level. The Rewilding Europe initiative was established in 2009 based on the principles of wildness. It hopes to restore 1 million hectares of land across 10 sites throughout Europe. An important aspect of Rewilding Europe is to ensure the sustainability of wilder lands with rich biodiversity in an increasingly populated world. A benefit to humans economically and culturally is at the heart of the programme.
The concept of rewilding is not strictly defined. Approaches to rewilding differ. Additionally rewilding is highly context dependent in terms of geography and taxa involved. The Oostvaardersplassen in the Netherlands is a controversial example of a “wild experiment” (Lorimer and Driessen, 2013). The programme underway at Oostvaardersplassen is based on the opinion of the ecologist Frans Vera as to what a Pleistocene ecological baseline would look like. The consensus view that a natural Europe would be covered in closed-canopy forest views the achievements of Oostvaarsdersplassen somewhat negatively, where the climax ecosystem is one of ungulate dominated grassland. An undeniable benefit of the Oostvaardersplassen Natural Park is that it has established an element of wildness in an area stripped of wilderness. However could it be argued that it is better to follow a more focused approach to ecological restoration?
The textbook example of rewilding is the Yellowstone National Park. The Gray wolf (Canis lupus) has faced local extinction across large parts of its historic range. Gray wolves were reintroduced into Yellowstone National Park in 1995-1996. This has had far reaching ecological impacts on regulation of ungulate populations and the growth of woody vegetation. Arguably rewilding in Yellowstone National Park via the reintroduction of the Gray wolf for purposes of ecosystem restoration rather than wolf recovery has increased the ecological function of Yellowstone making it a richer, more biodiverse ecosystem. Recent work has questioned however whether wolves are having a causative effect on Aspen growth in Yellowstone.
Looking to the future
The examples above demonstrate that rewilding can be used as a tool for protecting species with a dwindling population and increasing damaged ecosystem function. It is worth noting that wildlife reintroductions have a success rate of only 28%. Despite this, rewilding does offer a cheaper and arguably more sustainable form of ecosystem management. However there needs to be a coherent conservation focus, with an established baseline for effective monitoring. This would avoid problems and controversies as have arisen in the Oostvaardersplassen. This can be overcome by having a large knowledge base and using a case by case approach.
One constant achievement across different rewilding projects is that such projects raise public awareness of nature and wildness. This will be increasingly important in a world with 7 billion people and counting. Perhaps in the future we will see collaborations between rewilding projects and the developing Red List of Ecosystems to achieve specified targets.
1. Lorimer, J. and Driessen, C. (2013) Wild experiments at the Oostvaardersplassen: rethinking environmentalism in the Anthropocene. Transactions of the Institute of British Geographers 39 169-181.
2. Monbiot, G (May, 2013) A manifesto for rewilding the world. At http://www.monbiot.com/2013/05/27/a-manifesto-for-rewilding-the-world/ (Accessed: 10/12/2014).
3. Sandom, C. et al. (2013) Rewilding in Key Topics in Conservation Biology 2 Eds. Macdonald, D.W. and Willis, K.J. (John Wiley and Sons, Ltd) pp 430-451.
4. Seddon, P.J. Griffiths, C.J. Soorae, P.S. Armstrong, D.P. (2014) Reversing defaunation: Restoring species in a changing world. Science 345 406-412.