Drawing a line on a map does not protect anything on its own. Whether a reserve works depends on how big it is, what shape it is, what sits around it, and whether anyone is actively managing it. This is one of the most reliable long-answer topics in the whole unit.
📚 What you need to know
Habitat conservation works either by protecting wild areas (leave it alone) or by active management (intervene to keep it in a chosen state).
Active management includes controlled burning, reforestation and invasive species control.
Good design depends on knowing the biology of the target species and choosing the right size and shape.
The five design factors are size, shape, edge effects, corridors and proximity to human influence.
Edge effects are the changes that happen at the boundary between two habitats or land uses.
A high edge-to-area ratio is bad: more disturbance, more invasive species, more variable microclimate.
Many reserves use a core / buffer / transition zoning model to cut edge effects and protect the most vulnerable species.
Two ways to manage a habitat
Habitat conservation strategies aim to protect species by looking after the places they live. Broadly there are two philosophies, and they suit different situations.
Protection of wild areas
Set land aside, leave it in its natural state, and keep it free from significant human interference so ecosystems can function naturally.
Best where the ecosystem is still largely intact.
Cheap to run once the land is secured.
Example: large protected blocks of the Amazon Rainforest.
Active management
Human intervention to maintain or restore a habitat to a desired condition. Needed where the habitat is semi-natural or already damaged.
Controlled burning to manage grassland and forest and favour chosen plants.
Reforestation to restore deforested land.
Invasive species control to remove non-natives that threaten local biodiversity.
A question worth thinking about: if you have to burn, cut and weed a habitat every year to keep it the way you want, is it really “natural”? Many European habitats are semi-natural — they only exist because people have managed them for centuries. Saying that in an evaluation answer shows real understanding.
Biodiversity: a wide range of wildlife including rare and endangered plants, birds and insects, such as bitterns, marsh harriers and swallowtail butterflies.
Water level control: sluices and pumps keep levels right for wetland plants and animals, stopping areas becoming too dry or too flooded.
Reed cutting: stops the wetland becoming overgrown and keeps open water, which some species need.
Wildlife monitoring: regular surveys of populations, plus removal of non-native species that could take over.
Surrounding land use: mainly agricultural, so nutrient runoff and water use have to be managed carefully.
Case study
Zealandia ecosanctuary, Wellington, New Zealand
Habitat: forest and scrubland, right next to a city.
Pest-exclusion fencing: a predator-proof fence rings the sanctuary and keeps out rats, stoats and possums — the main threats to New Zealand’s native species.
Reintroduction: species such as the little spotted kiwi and the tuatara have been put back into the area, and populations that had crashed because of predation have recovered.
Surrounding land use: urban, but the fence isolates the sanctuary, creating a safe island of habitat inside the city.
Zealandia is a useful example because it shows a reserve can succeed close to a city — but only with expensive, continuous active management.
Knowing the target species first
Before you design anything, you need to know what the species actually needs. The syllabus lists four things:
🧩 Biology you need before you draw the boundary
Habitat requirements — the specific conditions needed to thrive: food, water, shelter, breeding sites.
Home range — how much area an individual or group needs to roam and find resources.
Life cycle — different life stages often need different habitats, so a reserve must cover all of them.
Home range is the one that decides size. A reserve big enough for butterflies is nowhere near big enough for wolves or elephants. If the reserve is smaller than the home range, the animals leave it — and that is where human-wildlife conflict starts.
Size, shape and everything at the edges
Five design factors come up again and again. Learn them as a list, because a question like “outline the factors to consider when designing a protected area” is a straight recall of these.
Design factor
Why it matters
Size
Larger areas support more species, hold larger populations and contain a greater range of habitats. The area must be big enough to keep populations of the target species viable in the long term.
Shape
Shape affects how habitats are distributed and how organisms move. A complex, straggly shape increases edge effects; a shape that is too simple may not include enough habitat variety. Irregular shapes that follow rivers and ridges can give better connectivity.
Edge effects
Changes that occur at the boundary between two habitats or land uses. Reserves with a high edge-to-area ratio suffer more human disturbance, more invasive species and more variable microclimates. Minimise them with compact shapes or buffer zones.
Corridors
Narrow strips of land connecting otherwise isolated habitat patches. They let organisms move, allow gene flow between populations, add habitat and increase the effective size of a reserve. Their usefulness depends on width, length and surrounding land use.
Proximity to human influence
Reserves near settlements or infrastructure face more habitat destruction, pollution and hunting. Design has to balance accessibility against human impact.
The left reserve has far more boundary for the same amount of land, so a much larger share of it is exposed to disturbance, invasive species and drying winds.
Why edge effects do so much damage
The edge of a reserve is not the same environment as the middle. It is windier, drier, brighter and noisier, and it is where people, pets, livestock and weeds get in. Species that need deep interior habitat simply cannot live there.
So the useful number is not total area — it is interior area. Two reserves can cover the same hectares while one has almost no true interior at all. That is exactly why compact shapes and buffer zones matter.
Core, buffer and transition zones
A lot of large protected areas, including UNESCO biosphere reserves, use a three-zone model. It is a neat solution to a real problem: people need to use land, but the most vulnerable species need to be left alone.
Zoning does two jobs at once: it shields the most sensitive habitat, and it gives local communities a legal place to keep making a living.
Case study
UNESCO biosphere reserve: the Great Barrier Reef, Australia
Location: northeast coast of Australia. Biodiversity: over 1500 species of fish, 411 types of hard coral, plus marine mammals, birds and reptiles.
Core areas: pristine reef with minimal or no human activity, protecting the most vulnerable species.
Buffer zones: limited, regulated activity such as sustainable fishing and sustainable tourism.
Transition zones: outer areas where sustainable resource use and human activity are encouraged alongside conservation.
Climate change: warming seas cause coral bleaching; management includes monitoring and researching heat-resistant coral.
Overfishing: managed through fishing regulations and quotas.
Tourism: visitor numbers and activities are controlled to limit damage.
What surrounds the reserve
A reserve is never a sealed box. Whatever happens on the land next door leaks in, which is why surrounding land use is a design factor in its own right.
Agricultural land: pollution risk from nutrient runoff, habitat fragmentation, and human-wildlife conflict when animals raid crops or livestock.
Urban areas: more disturbance and more invasive species, but also better access for education and recreation.
Industrial areas: pollution and habitat destruction.
Distance from urban centres
Close to a city
Easier access for managers and for public education.
Visitor income and volunteers are easier to get.
But: higher human pressure and constant disturbance.
Remote location
Less disturbance, natural state better preserved.
Fewer conflicts with settlements.
But: hard and costly for conservation staff to reach and manage.
EXAM QUESTION
Explain how the shape of a protected area can affect its biodiversity. [4]
Link shape to edge
A long, thin or complex shape has a high edge-to-area ratio, so a large proportion of the reserve is boundary habitat.
Say what edges do
Edges are exposed to human disturbance, invasive species and variable microclimate, so interior species cannot survive there.
Compare
A compact shape has more interior habitat for the same area, supporting more interior-dependent species.
Add the nuance: an irregular shape following a river or ridge can improve connectivity, so compact is not always best.Mechanism + consequence + a nuance
EXAM QUESTION
Outline two reasons why wildlife corridors are used in protected area design. [2]
Reason 1
They let organisms move between isolated patches, allowing gene flow and reducing inbreeding in small populations.
Reason 2
They add habitat and increase the effective size of the reserve, so larger populations can be supported.
Two clear, separate reasons
💡 Exam tip
Memorise the five design factors in order: size, shape, edge effects, corridors, proximity to humans. That list alone answers several past questions.
Say edge-to-area ratio, not just “edges”. It is the phrase that shows you understand the mechanism.
Always link design to a species need. “Large enough for the home range of the target species” scores better than “bigger is better”.
Have one active management case study ready (Norfolk Broads or Zealandia) and one zoning case study (Great Barrier Reef).
For corridors, remember the caveat: effectiveness depends on width, length and surrounding land use.
If a question shows you a map of reserves, comment on shape and connectivity, not just size.
⚠ Common mix-up
Buffer zone is not the same as transition zone. Buffer = limited regulated activity next to the core. Transition = outer area where sustainable economic use is actively encouraged.
Edge effects are not always negative for every species. Some edge specialists thrive there. The problem is for interior species.
Corridors are not automatically good. They can also spread disease, invasive species and fire between patches.
“Protected” does not mean “managed”. Some habitats degrade if you leave them alone, because they depend on grazing, cutting or burning.
Bigger is not always achievable. In an evaluation, mention cost, land ownership and competing land uses.
Do not describe the Great Barrier Reef as one uniform protected area. The whole point of it is the zoning.
Up next: Rewilding and Regeneration — what happens when you stop managing a landscape tightly and let natural processes take over instead.
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