Conservation: In Situ and Ex Situ

Conservation is the active management of biodiversity to prevent loss of species, habitats and genetic variation. Broadly, there are two complementary approaches: in situ (on-site — protecting species in their natural habitats) and ex situ (off-site — preserving species outside their natural habitats, for example in zoos, botanic gardens or seed banks). OCR A-Level Biology A specification 4.2.1 (h)–(j) requires you to evaluate both strategies and to know the international agreements that support them.

Key Definitions:

• In situ conservation — conservation of species in their natural habitat.
• Ex situ conservation — conservation of species outside their natural habitat.
• SSSI — Site of Special Scientific Interest (UK designation).
• CITES — Convention on International Trade in Endangered Species of Wild Fauna and Flora.
• CBD — Convention on Biological Diversity (Rio Convention, 1992).

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Overview

flowchart TD
    A[Conservation] --> B[In Situ]
    A --> C[Ex Situ]
    B --> B1[Nature reserves]
    B --> B2[National parks]
    B --> B3[SSSIs]
    B --> B4[Wildlife corridors]
    C --> C1[Zoos]
    C --> C2[Botanic gardens]
    C --> C3[Seed banks]
    C --> C4[Gene banks]
    A --> D[International Agreements]
    D --> D1[CITES]
    D --> D2[Rio Convention / CBD]

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In Situ Conservation

In situ conservation keeps species where they evolved, maintaining their ecological relationships, behaviours and evolutionary trajectories. It is generally preferred when possible because it:

• Preserves entire ecosystems including undiscovered species.
• Maintains natural behaviours (hunting, migration, breeding).
• Supports ongoing evolution and ecosystem services.
• Is usually cheaper per species than ex situ methods.

National Parks

National parks are large designated areas managed to balance conservation, recreation and sustainable use. The UK has 15 national parks (e.g. Lake District, Snowdonia/Eryri, Cairngorms), covering around 10% of the country. They protect landscapes and wildlife but also contain working farms and towns, which requires careful management of conflicting interests.

Nature Reserves

Nature reserves are smaller, more strictly managed sites focused primarily on wildlife. The UK has over 200 National Nature Reserves (NNRs) and more than 2,300 Local Nature Reserves (LNRs). Examples include the RSPB's Minsmere reserve in Suffolk (home to bitterns, marsh harriers and stone curlews) and the London Wetland Centre (restored from Victorian reservoirs).

Sites of Special Scientific Interest (SSSIs)

SSSIs are legally protected sites notified by Natural England (and equivalents in Scotland, Wales and Northern Ireland) because of their flora, fauna, geology or landforms. There are around 4,100 SSSIs in England alone, covering roughly 8% of the country. Landowners must seek consent before undertaking potentially damaging activities on an SSSI.

Wildlife Corridors

Habitat fragmentation leaves species stranded in isolated patches too small to sustain viable populations. Wildlife corridors — linear strips of habitat (hedgerows, woodland strips, river margins, green bridges over motorways) — reconnect these patches, allowing:

• Dispersal of individuals, spreading risk.
• Gene flow between subpopulations, maintaining genetic diversity.
• Range shifts in response to climate change.

The European Green Belt — a 12,500 km corridor along the former Iron Curtain — is one of the world's most famous examples. In the UK, the B-Lines initiative maps and restores pollinator corridors across the country.

Managed Nature: Active In Situ Conservation

In situ conservation is rarely a matter of leaving nature alone. Active management includes:

• Scrub clearance to maintain heathland and chalk grassland.
• Controlled grazing by cattle, ponies or sheep to prevent succession.
• Coppicing woodland to create the mosaic of light and shade needed by butterflies and woodland flowers.
• Reintroduction of lost species (beavers, cranes, large blue butterflies).
• Predator control to protect ground-nesting birds from feral cats or mink.
• Culling of overabundant deer, grey squirrels or invasive species.

Exam Tip: OCR mark schemes often ask you to "evaluate" in situ vs ex situ. A strong answer lists advantages AND disadvantages of each, then concludes with a judgement. Examples of disadvantages include continuing pressure (poachers still reach reserves), inadequate size, and reserves being "paper parks" without enforcement.

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Ex Situ Conservation

Ex situ conservation is used when in situ conservation is impossible or insufficient — for instance when a species is critically endangered, its habitat is destroyed, or immediate rescue is needed. It is sometimes described as a "Noah's Ark" approach. Ex situ strategies include:

Zoos

Modern zoos play several conservation roles:

1. Captive breeding programmes to maintain populations too small to be viable in the wild.
2. Reintroduction programmes returning captive-bred individuals to restored habitats.
3. Education and fundraising to support field conservation.
4. Research on behaviour, genetics, nutrition and veterinary care.

Case Study: Arabian Oryx

The Arabian oryx was hunted to extinction in the wild by 1972. A captive population of just nine individuals in Phoenix Zoo (the so-called "World Herd") was used to found a breeding programme. In 1982, the first oryx were released back into Oman; today, several thousand live in reintroduced populations. In 2011 the IUCN downlisted the species from Extinct in the Wild to Vulnerable — the first mammal ever to make that transition.

Case Study: California Condor

Reduced to 22 individuals in 1987, every wild California condor was captured for a last-chance captive breeding programme. Through carefully managed matings (using puppets to feed chicks so they would not imprint on humans), the population now numbers over 500, including more than 300 flying free in California, Arizona and Mexico.

Disadvantages of Zoos