Passive rewilding refers to actively unmanaged environments that are allowed to regain natural dominance, typically after their abandonment. A type of rewilding, passive rewilding aims to restore natural ecosystem processes via minimal or the total withdrawal of direct human management of the landscape,Gillson L, Ladle RJ, Araújo MB. 2011. Baselines, patterns and process. In: Ladle RJ, Whittaker RJ, Eds. Conservation biogeography. Oxford: Wiley-Blackwell. p 31–44. https://doi.org/10.1002/9781444390001.ch3 Passive rewilding allows natural processes to restore themselves, and enables a particular level of chaos as woodlands reclaim land, species return and ecological disturbances like wildfires, pests and floods contribute to the area.
Sometimes referred to as natural regeneration, spontaneous regeneration, and, informally, as nature's reclamation, it differs from other forms of rewilding in that direct human management or intervention is absent, whereby the environment is subsequently overgrown and occupied by natural elements on its own. In 1998, science fiction author Bruce Sterling coined the term involuntary park to describe previously inhabited areas that for environmental, economic, or political reasons have lost their value for technological functionalism and been allowed to return to an overgrown, feral state.
Passive rewilding includes abandoned human settlements and developments, such as post-agricultural lands for instance, that are intentionally left undisturbed and later become spontaneously overtaken by foliage and wild animals. Such occurrences are known to exist in numerous locations around the world. Degraded or abandoned land is actually the forefront of a global reforestation.
Ecological processes
There are three important factors to passive rewilding; Reviving trophic complexity, or biodiversity, by allowing wildlife to return (such as by limiting hunting), though in other cases it may involve resettlement. The second factor is allowing landscapes to rejoin, so in a way that plants and animals can travel around. The third component is permitting erratic disturbances such as fires, pests and floods. However, allowing nature run haphazardly and being left to chance is unacceptable to the traditional methods of ecological restoration and can be a complicated matter to accept for westerners. Passive rewilding may also expand to any area of formerly actively managed land (either rural or urban) that is currently experiencing extremely limited active management or none at all. Structures occupying urban areas that have been demolished, leaving patchy areas of green space that are usually untended and unmanaged, form an involuntary park.
Passive rewilding is a capable method for expanding tree cover and restoring biodiversity through the means of abandoning land management and permitting natural vegetation succession to occur for the restoration of natural habitats and biodiversity, expand native forest, and to increase ecosystem services and strength, and as well as for scientific research. Land is abandoned to passive rewilding either purposely, or due to socio-economic change. A strong argument in favor of passive rewilding is the minimal cost approaches to restoration, particularly on a large scale. Though widespread forest growth can transform into a homogenous landscape, and biodiversity is generally against homogeneity. Garden plants escaping gardens and rewilding the surrounding areas are called escaped plants, although these have detrimental effects on native species and communities, in addition to being weedy and invasive.
Natural forest regeneration Forest recovery has been occurring in abandoned pastures, scrubby bush and forest margins throughout Europe and North America, since nature abhors an ecological vacuum and therefore hastily fills it. Passive rewilding as de-management may benefit ecosystems in the United Kingdom as it liberates resources and leads to ecological consequences which benefit both wild nature and society. Evidence allows for short-medium term prognoses in passive rewilding sites in Western Europe. The abandonment of agricultural land use practices drives the natural establishment of forests through ecological succession in Spain. This spontaneous forest establishment has several consequences for society and nature, such as increase of fire risk and frequency and biodiversity loss. Regarding biodiversity loss, research findings from the Mediterranean basin showed that this is very site-dependent. More recently, the abandonment of land is also discussed by some as an opportunity for rewilding in rural areas in Spain.
Removing sheep is one of the first steps in passive rewilding in Britain, as they can eradicate wildflowers and other essential species. Though old pig breeds can remain as a substitute for wild boars. If there is a scarcity of plants, these species are replanted to promote their spread. Fences are also removed and wetlands are created, in addition to removing non-native species. In Portugal, grazing animals such as the bison can clear land and establish open areas where biodiversity can thrive, whereas wild boars may disturb the soil as they search for food. In Britain, farmland bird species decreased as passive rewilding progressed, although woodland birds increased. In the process of passive rewilding, thorny shrub bushes covered 53% of the site in Britain, and former hedges became degraded. Passive rewilding may also occur in an urban prairie, which is a vacant urban land that has been restored to green space, although rewilding here is not always passive as many urban prairies tend to be managed.
Rewilding abandoned sites
Involuntary parks where human presence is severely limited can host animal species that are otherwise extremely threatened in their range. When such parks develop in an urban or formerly urban location, it may become the target of urban exploration for hobbyists. The aesthetics of nature's reclamation of urban buildings has acquired the attention of artists, photographers and architects alike. Observers are attracted to seeing nature rewilding decaying structures such as broken windows, cracks on the walls, and other spaces built by man. Enthusiasts view such natural reclamation of neglected areas as inspirational and poetic, as it serves as a reminder of impermanence and how beauty exists even in decay. Regarding involuntary parks, Sterling states:
The continent's imperiled rims has become a new kind of landscape — the involuntary park. They are not representations of untouched nature, but of vengeful nature... Abandoned areas of the planet can no longer "revert to Nature" as they once supposedly did. Instead, they must revert to Next Nature, becoming weird "involuntary parks" such as the Cypriot Green Line, a long, human-free strip of flammable weeds and weed-trees, junkyards and landmines.
Abandoned towns, villages, farmlands, disused railways, mines, quarries and airfields, or areas experiencing urban decay and deindustrialization, may be subject to a resurgence in ecological proliferation and rewilding as human presence is reduced. Wildlife will rebound and reclaim abandoned human structures in such zones, when given the chance. This opportunity is as basic as humans leaving a place to be regenerated by nature. While Bruce Sterling's original vision of an involuntary park was of places abandoned due to collapse of economy or rising sea level, the term has come to be used on any land where human inhabitation or use for one reason or another has been stopped.Cascio, J. (2005): The Green Ribbon , from WorldchangingFor an example of the term used with land-mines, see Landmines and Involuntary parks
Other man-made environments that can be swarming with new ecosystems include temple ruins, areas considered dangerous due to pollution, abandoned theme parks, shipwrecks, military exclusion zones/exclusion zones and abandoned vehicles. In urban areas, moss covers disintegrating buildings, sand dunes or vegetation engulf entire houses, and trees and animals scramble over former walkways. After a lack of maintenance in buildings, the elements freely impact the structures, therefore roofs degenerate and permit rain to seep in, and walls fracture, allowing roots to permeate, and spaces open up to create fortuities for seeds to root. The walls and floors ultimately become habitats for wildlife, while windows and roofs turn into sanctuaries.
Regional examples Africa
The ruins of Sabratha in Libya are undergoing severe coastal erosion, with the public baths, the olive-press building, and the 'harbor' showing the most damage as their structures have crumbled due to storms and unsettled seas, while rising sea levels further compromise the integrity of the site. Wildflowers have overgrown the Timgad ruins in Algeria. Olive trees and wildflowers have reclaimed the Roman ruins of Dougga in Tunisia.
After Kolmanskop and Elizabeth Bay in Namibia were abandoned by 1956, the homes in the villages became filled and eventually submerged in sand. The wreck of the Eduard Bohlen in Namibia has been largely engulfed by sand. Plaatjieskraal in South Africa, once farmland, has since been overtaken by sand dunes, with renosterveld flora now dominating the area.
Oceania Gladesville Mental Hospital (formerly the Tarban Creek Lunatic Asylum) on the Lower North Shore features vegetation that cloaks its decaying walls. The marooned wreck of SS Ayrfield in Parramatta River in Homebush has become a mangrove forest, and is therefore a protected marine vegetation critical for fish habitat. Paronella Park in Queensland is an involuntary park featuring a concrete castle now overrun by trees and weeds. The remains of SS Yongala off the coast of Queensland is now home to hundreds of various species, that include loggerhead turtles, marbled electric rays, bull sharks and moray eels. The Montebello Islands, the site of three British atmospheric nuclear weapons tests in 1952 and 1956, are now involuntary parks that underwent passive rewilding.
In a village at Mangapurua Valley, New Zealand, historical farming and gardening efforts by soldiers and families indicates that most of the homes, culverts and farms in the Valley are now overrun with grass and marshes, with some fruit and rose trees surviving, indicating historical human presence. Land Information New Zealand (LINZ) permits the vacant residential red zone—now functioning as an involuntary park—in Christchurch, which suffered severe damage in the 2010 and 2011 Christchurch earthquakes, to be used temporarily (for up to five years) for activities such as community gardening, mountain biking, and beekeeping.
Asia
Abandoned homes in the Fukushima Exclusion Zone are reclaimed by plant life, and the fauna there include Japanese macaques, common raccoon dogs, Japanese serow and red foxes. Apartment blocks in Hashima Island, Japan are now overwhelmed with weeds, and dense vegetation hang off their dilapidated balconies. Hachijo Royal Resort on Hachijō-jima is an abandoned luxury hotel built in the 1960s that is now overgrown and severely dilapidated.Anika Burgess, "Japan's Abandoned Hotels Are Being Reclaimed by Nature ", Atlas Obscura, 6 September 2017. Retrieved 16 November 2025. The Korean Demilitarized Zone is hypothesized to house not only Korean tigers, but also the critically endangered Amur leopard, although neither have been photographed there since the late 20th century. The once-bustling village of Houtouwan in China has been entirely reclaimed by foliage plants after residents began to leave it in the 1990s. The village is also a tourist site now, where visitors can tour the abandoned, museum-like buildings.