Most conservation asks “how do we stop things getting worse?”. Rewilding asks something bolder: can we put the natural processes back and then step out of the way? It is the part of this topic where ESS gets genuinely interesting — and genuinely controversial.
📚 What you need to know
Human activities such as deforestation and overharvesting disrupt, damage and destabilise ecosystems.
Ecosystem-level conservation aims to restore stability by restoring natural ecosystem processes: predator-prey relationships, seed dispersal, nutrient cycling.
This kind of ecosystem restoration project is called rewilding.
The four main strategies are species reintroduction, improving habitat connectivity, stopping agriculture and limiting human influence.
Reintroducing an apex predator can reduce herbivore numbers and let vegetation recover — a trophic cascade.
Reintroducing a keystone species such as the beaver changes the physical structure of the habitat.
The aim overall is to minimise direct human management and let ecosystems self-regulate.
What rewilding actually means
Rewilding is not just “planting some trees”. It is about restarting the processes that used to run the ecosystem, and then letting them do the work.
DefinitionRewilding is ecosystem restoration that aims to bring back natural processes and species, so that the ecosystem can self-regulate with minimal ongoing human management.
The processes that matter most are the ones that shape everything else:
Predator-prey relationships — predators control herbivore numbers and behaviour.
Seed dispersal — animals move plants around, which is how habitats regenerate.
Nutrient cycling — dung, carcasses and decay move nutrients back into the soil.
Notice the difference between this and the reserve management on the last page. There, humans decide what the habitat should look like and keep it there by cutting and burning. Here, humans set the conditions and then accept whatever the ecosystem produces — even if it is not what they expected.
The four rewilding strategies
The order matters. Reintroducing a predator into a fragmented, unconnected landscape rarely works, which is why connectivity usually comes first.
1. Species reintroduction
Putting back an apex predator reduces herbivore populations, which lets damaged vegetation recover, which boosts plant diversity, which raises total biodiversity. That chain is called a trophic cascade.
The famous case is the reintroduction of wolves to Yellowstone National Park in the USA. The wolves helped control deer numbers, and certain types of vegetation recovered as a result.
Each step is a testable claim, which is why cascades like this get argued over. In an evaluation you can note that the size of the Yellowstone effect is still debated by ecologists.
Reintroducing a keystone species works differently — it changes the structure of the habitat rather than the food web. Beavers have been reintroduced to parts of the UK. They build dams, and the dams create large wetland areas that support a wide range of wildlife that was not there before.
2. Improving habitat connectivity
This means joining up fragmented habitats so species can move freely. Wildlife corridors, such as hedgerows across farmland, connect small pockets of habitat.
The logic chain is worth learning: connected habitat means animals can roam over a larger area, which increases the resources available to them, which allows larger populations to establish, which makes those populations less likely to go extinct.
3. Stopping agriculture
Land that was farmed is allowed to return to its natural state. The Knepp Estate in England is the best-known example. The former farmland now supports free-roaming wild ponies, pigs and longhorn cattle, and those animals promote biodiversity by disturbing soil, dispersing seeds and grazing unevenly, so no single plant species takes over.
4. Limiting human influence
This means preventing the harvesting of resources — logging, fishing — and using ecological management techniques such as controlled grazing or burning only where they are needed to get a habitat started. The aim is to minimise direct human management and let the ecosystem self-regulate as far as possible.
Spot the tension. Strategy 4 says minimise human management, but controlled grazing and burning are human management. Rewilding projects constantly argue about how much intervention is acceptable. Saying so in an evaluation question is exactly the kind of critical thinking ESS rewards.
Case study
Restoration of Hinewai Reserve, New Zealand
Location: Banks Peninsula, New Zealand. Once farmland, now privately owned with the aim of restoring the area’s natural ecosystem.
Initial intervention: some human work at the start, mainly removal of non-native species.
Ongoing approach: managed with minimal human intervention so native communities can be restored by succession.
Access: human activity is limited, though the public can walk in the reserve.
Successes: rapid regrowth of native bush, more native birds, and effective control of invasive species.
Hinewai is the cleanest example of the rewilding philosophy: intervene once to remove the blockers, then let succession do the rest.
Notice how succession links straight back to earlier topics. Rewilding is basically deliberate secondary succession — you clear the barriers and let the sere run. If you can make that link in an essay, do it.
Where rewilding gets difficult
Do not write about rewilding as if it always works. The problems are real and examiners want to see them.
What it delivers
Restores biodiversity by bringing back species with important ecological roles.
Improves ecosystem services: carbon storage, flood prevention, water purification.
Creates ecotourism income for local communities.
Cheaper long term than permanent intensive management.
What goes wrong
Land-use conflict: the same land could grow food, which matters most where land is scarce.
Unintended consequences: reintroduced predators may attack livestock.
Economic pressure: governments may prioritise mining or logging over conservation.
Outcomes are unpredictable, which makes funders nervous.
EXAM QUESTION
Explain how reintroducing an apex predator can increase biodiversity in an ecosystem. [4]
Start the chain
The predator reduces the population of herbivores and changes where they graze.
Follow it through
Grazing pressure falls, so vegetation such as trees and shrubs recovers, increasing plant diversity.
Finish it
The recovered vegetation provides habitat and food for other species, so total biodiversity rises.
Named example: wolves reintroduced to Yellowstone National Park controlled deer numbers and allowed vegetation to recover.A full cascade + a named example
EXAM QUESTION
Suggest two reasons why a rewilding project might be opposed by local people. [2]
Reason 1
Land taken out of farming reduces food production and farm income, which matters where land is scarce.
Reason 2
Reintroduced predators may kill livestock, creating direct financial loss and human-wildlife conflict.
Two distinct, concrete reasons
💡 Exam tip
Learn the four strategies as a list. Reintroduction, connectivity, stopping agriculture, limiting human influence.
Use the word self-regulate — it is the defining feature of rewilding compared with normal habitat management.
For cascades, write every link. Jumping from “wolves return” to “biodiversity rises” loses the middle marks.
Have two named projects ready: Yellowstone (predator reintroduction) and Knepp or Hinewai (land returned to nature).
Beavers are the best keystone example because the mechanism is physical and easy to describe: dams create wetland.
Any “discuss” or “evaluate” question needs the land-use conflict argument. It is the strongest counterpoint.
⚠ Common mix-up
Rewilding is not the same as reforestation. Planting trees is one method; rewilding is about restoring processes, and sometimes means not planting anything.
Apex predator and keystone species are not synonyms. Beavers are a keystone species and are not predators at all.
“Minimal management” does not mean “no management”. Most projects start with invasive species removal or fencing.
A trophic cascade is not instant. Vegetation recovery takes years or decades, and results are often contested.
Do not assume reintroduced species will stay put. Home range and connectivity decide that.
Writing “rewilding is good for nature” with no mechanism and no example scores almost nothing.
Up next: Biodiversity as a Planetary Boundary — zooming out from single projects to the global limit we have already crossed.
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