The big idea: Rewilding means helping a damaged ecosystem repair itself by putting back the natural processes that used to run it — and then stepping back to let nature take over.
Instead of managing every detail forever, the aim is a self-sustaining ecosystem that looks after itself.
The headline tool is bringing back a keystone species — a species whose activity shapes the whole community.
Ordinary conservation
- Protects species as they are now
- Often needs ongoing human management
- Aims to stop further loss
Rewilding / restoration
- Restores lost natural processes
- Aims for a self-sustaining ecosystem
- Aims to reverse damage and let nature run it
Two words to be sure of: Keystone species — a species that has a very large effect on its ecosystem relative to its numbers (for example a top predator or a beaver).
Degraded ecosystem — an ecosystem that has been damaged so that it works less well (for example a cleared forest or a drained wetland).
Rewilding works by restoring natural processes — the things that healthy ecosystems do on their own, such as grazing, predation, flooding and seed dispersal.
Once these processes are running again, the ecosystem can maintain itself without constant human input.
- Rewilding
- Restoring natural processes to a degraded ecosystem so it becomes self-sustaining, often by reintroducing a keystone species.
- Reintroduction
- Releasing a species back into an area where it used to live but had died out locally.
- Ecosystem restoration
- Repairing a damaged ecosystem so its natural processes and biodiversity recover.
- Natural process
- A self-running ecosystem activity such as grazing, predation, flooding or seed dispersal.
| Rewilding method | What it does | Example process restored |
|---|---|---|
| Reintroduce a keystone species | Puts back a species whose activity shapes the community | predation / dam-building |
| Re-establish natural grazing | Lets large herbivores keep vegetation open and varied | grazing |
| Restore natural water flow | Removes drainage or dams so wetlands and rivers behave naturally | flooding |
| Remove human controls | Stops fences, culling or planting so the system self-regulates | self-regulation |
| Replant / let native plants return | Rebuilds the plant community that supports everything else | seed dispersal |
| Reconnect habitats (corridors) | Lets species move and spread between patches | dispersal / gene flow |
The keystone idea: A keystone species has an effect far bigger than its numbers.
Bring beavers back and they build dams → wetlands form → many other species return. Bring a top predator back and it controls grazers → plants recover → the whole food web shifts.
That is why reintroducing one keystone species can restart a chain of natural processes across the ecosystem.
Reintroducing a keystone species sets off a cascade that restores biodiversity.
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How this is tested: On Paper 1A (multiple choice) you are asked to identify an action that counts as rewilding or that minimises biodiversity loss (rewilding a degraded ecosystem).
On Paper 2 a 2-mark Outline question can ask you to give rewilding methods that restore natural processes — and may say other than reintroducing a keystone species, so you must know more than one method.
IB-style question — outline rewilding methods
A nature charity is rewilding a degraded river valley. Outline two rewilding methods, other than reintroducing a keystone species, that could help restore its natural ecosystem processes. [2]
How to score both marks
- Pick methods that restore a NATURAL PROCESS, not a single species. The question rules out the keystone reintroduction, so name methods that bring back grazing, water flow, native plants or connectivity.
- Method 1 — restore natural water flow. Remove old drains or artificial banks so the river can flood the valley naturally, recreating wetland habitat.
- Method 2 — let native vegetation return. Stop intensive farming/planting and allow native plants to recolonise, rebuilding the plant community that supports the food web.
- Answer the command term (Outline): Two valid methods are restoring natural water flow (re-flooding) and allowing native vegetation to return — each restores a natural process so the ecosystem can sustain itself. (1 mark per correct method.)
Final answer
Any two of: restore natural water flow / re-flooding; allow native vegetation to return; re-establish natural grazing by herbivores; reconnect habitats with corridors; remove human controls (fencing, culling) so the system self-regulates. (Not the keystone reintroduction, which is excluded.)
✓ What a 2-mark answer looks like: Two different methods, each clearly restoring a natural process — for example re-flooding the valley and letting native plants return.
Listing two versions of the same idea, or naming the excluded keystone reintroduction, would only score once or not at all.