What Is Rewilding: Restoring Ecosystems, Key Projects, and Controversies

What Is Rewilding?

Rewilding is a large-scale conservation strategy that aims to restore self-regulating, biodiverse ecosystems by reintroducing missing species (particularly large predators and herbivores), reconnecting habitat fragments, and allowing natural processes — predation, grazing, disturbance, decomposition — to govern ecosystem dynamics rather than active human management. Unlike traditional conservation, which often focuses on preserving specific species or habitats in a particular historical state, rewilding envisions ecosystems as dynamic, self-organizing systems capable of determining their own structure and function if given the space and the species they need.

The term "rewilding" was introduced by conservation biologists Michael Soulé and Reed Noss in their influential 1998 paper, which proposed a framework centered on the "3 Cs": Cores (large wilderness areas), Corridors (habitat linkages between core areas), and Carnivores (apex predators whose restoration can trigger cascading ecological benefits). The concept has since expanded and diversified, encompassing both the passive rewilding of agricultural land abandoned due to rural depopulation and the active reintroduction of extirpated species.

Ecological Foundations: Trophic Cascades

The scientific foundation of rewilding rests heavily on the concept of trophic cascades — the indirect effects that apex predators have on ecosystem structure and function by regulating the behavior and populations of herbivores, which in turn affects vegetation, soils, and waterways. The most famous documented trophic cascade is the effect of wolf reintroduction in Yellowstone National Park.

Before wolves were extirpated from Yellowstone in the early 20th century, elk herds had grazed heavily in riparian (streamside) areas, preventing the establishment of willows, aspens, and cottonwoods — trees critical to bank stability and to species like beavers. After wolves were reintroduced in 1995–1996, elk behavior changed significantly: elk avoided prolonged grazing in open river valleys where they were most vulnerable to predation. This behavioral shift — called the "landscape of fear" — allowed vegetation recovery along stream banks. Increased vegetative cover stabilized banks, reducing erosion; beaver populations rebounded, creating ponds that further transformed hydrology; songbird diversity increased; and river channel morphology measurably changed. The phrase "how wolves change rivers" entered conservation discourse as a metaphor for trophic cascade effects.

Types of Rewilding

Rewilding encompasses several distinct approaches that differ in ambition, methodology, and scale:

• Trophic rewilding: Focused on restoring missing trophic levels — particularly apex predators and megaherbivores — to reactivate ecological processes. Emphasizes top-down regulation of ecosystems.
• Passive rewilding: Simply removing human management pressure (stopping grazing, mowing, or agricultural cultivation) and allowing ecosystems to spontaneously regenerate. Common on abandoned agricultural land in Europe, particularly in depopulating rural areas of Spain, Portugal, and Eastern Europe.
• Pleistocene rewilding: The most radical proposal — reintroducing large mammals (or their ecological proxies) to fill roles lost when megafauna were extirpated during the Pleistocene-Holocene extinctions (~10,000–15,000 years ago). Proposals include introducing African and Asian elephants to Russia's Siberia as proxies for extinct woolly mammoths (the "Pleistocene Park" project of Sergey Zimov).

Major Rewilding Projects

Controversies and Challenges

Conflicts with Agriculture and Livestock

The most contentious aspect of rewilding is the reintroduction of large carnivores — wolves, bears, lynx — into landscapes that include farming and livestock operations. Farmers and pastoral communities bear the direct costs (livestock predation, behavioral disruption of herds, psychological stress) while the ecological benefits are diffuse and often accrue to broader society and distant stakeholders. In Europe, the legal protection given to recovering wolf populations under the EU Habitats Directive has generated bitter political conflict in rural communities across France, Germany, Sweden, Italy, and the Netherlands, where wolf populations are expanding naturally rather than through managed reintroduction.

The Baseline Problem

Rewilding initiatives must decide which historical state they are aiming to restore — a choice that is inherently value-laden. Should the target be the ecosystem before European colonization? Before agricultural intensification? Before the Pleistocene extinctions? Different choices produce radically different prescriptions. Critics argue that ecosystems have changed continuously throughout history and that selecting any particular baseline as the "natural" state to restore is arbitrary.

Indigenous Land Rights

Large-scale rewilding initiatives — particularly proposals to create vast "wilderness corridors" — have been criticized for potentially displacing indigenous and local communities from their traditional lands in the name of ecological restoration. Conservation organizations have increasingly recognized the importance of Free, Prior, and Informed Consent (FPIC) from indigenous communities and of integrating traditional ecological knowledge into rewilding design, but tensions between conservation and land rights remain.

Rewilding and Climate Change

Rewilding has attracted increasing attention as a natural climate solution. Restored grassland ecosystems with large herbivores (like the Pleistocene Park model) could potentially help preserve permafrost soils in the Arctic by increasing snow compaction and reducing soil insulation — preventing the release of the vast carbon stores frozen in permafrost. Forest restoration absorbs carbon; restored wetlands sequester carbon in peat. Intact, biodiverse ecosystems are also inherently more resilient to climate change impacts than degraded ones. The potential of large-scale rewilding to contribute meaningfully to both biodiversity restoration and climate mitigation has made it an increasingly prominent topic in international conservation and climate policy discussions.