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097e145
NotesESS HLTopic 3.3Choosing the best strategy (and why)
Back to ESS HL Topics
3.3.71 min read

Choosing the best strategy (and why) (ESS HL)

IB Environmental Systems and Societies • Unit 3

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Contents

  • In situ vs ex situ (quick comparison)
  • Decision checklist (exam-friendly)
  • Typical “best answer”: combine both
  • Exam tips – how to score top marks
  • Exam-style question (step by step)
Choosing the best strategy at HL: Choosing the best conservation strategy works the same way for SL and HL. It's a natural fit for the HL focus on environmental economics — you weigh strategies by their costs, benefits and trade-offs to justify a choice.

Nothing extra to learn here — just practise justifying which strategy fits a situation.

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🆚 In situ vs Ex situ (what to choose?)

Big Idea: Most real conservation uses both approaches. In situ protects ecosystems long-term, while ex situ prevents extinction when the wild is too risky.

In situ

  • In the natural habitat
  • Protects ecosystems and many species
  • Keeps natural behaviours and interactions
  • Best long-term if threats can be reduced

Ex situ

  • Outside the natural habitat
  • Emergency protection for very threatened species
  • Supports breeding and genetic storage
  • Needs reintroduction and habitat repair

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📝 Decision checklist: choosing the best strategy

Use this checklist to justify your choice in evaluation questions.

  • Urgency of extinction risk (very high → ex situ backup)
  • Habitat condition (intact vs degraded)
  • Threat controllability (poaching, invasives, pollution)
  • Available space for a viable population
  • Genetic diversity potential
  • Cost and long-term management capacity
  • Local community support and fairness
High marks = name a strategy and justify it using 2–3 checklist points.

🤝 The strongest strategy is usually a mix

IB examiners reward answers that recognise no single strategy is perfect.

  • Step 1: Reduce threats in the wild (laws, enforcement)
  • Step 2: Protect and restore habitat (in situ)
  • Step 3: Create an ex situ safety net (breeding / seed bank)
  • Step 4: Reintroduce and monitor populations
Ex situ alone saves species short-term, but cannot replace habitat protection.

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🏆 Exam tips: in situ vs ex situ questions

9-mark structure: Top answers include comparison + evaluation + justified conclusion.
  • 1. Define both strategies briefly
  • 2. Compare effectiveness (ecosystems vs emergency rescue)
  • 3. Evaluate limitations of each
  • 4. Apply to context (habitat quality, threat level)
  • 5. Conclude with judgement (often a combined strategy)

IB-style question — Compare in situ vs ex situ — one advantage each

The Daintree Lowland Rainforest Reserve (Australia) protects the southern cassowary in situ. The Cairns Wildlife Dome holds cassowaries in captivity for breeding and public education. State one advantage of the in situ approach and one advantage of the ex situ approach for conserving the southern cassowary. [2]

How to answer it, step by step

  1. In situ advantage

    • Protects the whole ecosystem — cassowary's seed-dispersal role and food-web interactions are maintained, benefiting hundreds of co-dependent species.
  2. Ex situ advantage

    • Captive breeding = insurance population: if disease or cyclone devastates the wild population, captive stock prevents total extinction and enables reintroduction.

Final answer

1 mark per advantage — must include a reason/mechanism, not just name the strategy.

IB-style question — EVS and conservation choices [9-mark essay]

Explain how ecocentric, anthropocentric, and technocentric environmental value systems (EVS) lead to different choices between in situ and ex situ conservation strategies, using named examples. [9]

How to answer it, step by step

  1. Define all three EVS + link to strategy

    • Ecocentric → favours in situ (e.g. Białowieża Forest): nature has intrinsic value; zoos deny animal rights.

    • Anthropocentric → pragmatic mix: in situ for ecosystem services (Costa Rica parks); ex situ seed banks (Svalbard) for food security.

    • Technocentric → favours ex situ (e.g. Frozen Ark cryopreservation): science can fix problems; vast land reserves are unnecessary.
  2. Evaluate strengths + limits, then conclude

    • In situ is most cost-effective at scale but needs large intact habitat — politically hard in developing nations.

    • Ex situ saves species when habitat is already gone but risks inbreeding and can't restore ecological function.

    • Best programmes (e.g. kākāpō recovery) combine both — conservation success depends on context, not which EVS dominates.

Final answer

Markband 7–9: all three EVS defined + named examples + both strategies evaluated + explicit value-judgement conclusion. Listing strategies without naming the EVS = max 4. Listing EVS without linking to strategies = max 4.



HL. HL.c (ethics): HL students should engage with the concept of biorights (Naess, deep ecology) when discussing ecocentric objections to ex situ conservation, and may reference the 1992 Convention on Biological Diversity as an anthropocentric/intergovernmental framework. The tension between intrinsic value and instrumental value is a core HL ethics theme.

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In situ protects species in their natural habitat.

whether creating a protected area is an in situ or ex situ conservation strategy. [1 mark]

Related ESS HL Topics

Continue learning with these related topics from the same unit:

3.1.1Biodiversity and resilience
3.1.2Measuring biodiversity
3.1.3Natural selection
3.1.4Protecting Biodiversity
View all ESS HL topics

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