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IB DP ESS — Topic 3: Biodiversity and Conservation | SL & HL | Paper 1 & Paper 2
🎯 Learning Intentions By the end of this note, you will be able to:
- Define habitat conservation, rewilding, protected areas, and ecological corridors using IB-aligned ESS terminology.
- Explain how habitat fragmentation reduces biodiversity and the mechanisms by which conservation strategies attempt to reverse this process.
- Describe the design principles of protected areas, including the SLOSS debate and the role of edge effects, at local, regional, and global scales.
- Analyse the effectiveness of rewilding as a conservation strategy using ESS analysis parameters: scale, sustainability, trade-offs, and multiple perspectives.
- Evaluate the strengths and limitations of in-situ and ex-situ conservation approaches in maintaining biodiversity.
- Discuss contrasting worldviews — ecocentric, technocentric, and anthropocentric — in relation to habitat conservation and rewilding decisions.
- Compare and contrast different models of protected area management, including national parks, biosphere reserves, and community-based conservation.
Real-World Context & Relevance
In 1995, seventeen grey wolves were reintroduced into Yellowstone National Park, USA, after a 70-year absence. What followed was one of the most documented examples of ecological cascade in conservation history. Wolf predation reduced overgrazing by elk, allowing riverbank vegetation to recover, which stabilised stream channels, reduced erosion, and altered the physical geography of the park. Songbird populations increased as shrub cover returned; beaver colonies expanded; and the entire trophic structure of the ecosystem shifted. This phenomenon — a trophic cascade triggered by the reintroduction of a keystone predator — became the defining case study for rewilding and demonstrated that restoring a single species could regenerate an entire ecosystem.
Yet Yellowstone is not a universal template. Across Europe, rewilding projects face very different political, social, and ecological realities. The Rewilding Europe initiative, operating across ten landscapes from the Danube Delta to the Iberian Peninsula, must negotiate with farming communities, national governments, and competing land-use interests. Meanwhile, the IPBES Global Assessment (2019) reported that approximately one million species face extinction, with habitat loss identified as the primary driver. The scale of the crisis demands not just individual rewilding projects, but a systemic rethinking of how human societies relate to the land they occupy. These notes examine the full spectrum of habitat conservation strategies — from protected area design to ecological corridors to rewilding — and ask which approaches are most effective, for whom, and under what conditions.
🌍 Why This Matters Habitat loss and fragmentation are the leading causes of global biodiversity decline. Conservation strategies — including protected areas, ecological corridors, and rewilding — represent humanity's primary tools for reversing this trend. Understanding how these strategies work, their limitations, and the worldview tensions they generate is essential for evaluating real environmental policy decisions at every scale.
Core Concepts & Definitions
Before examining specific conservation strategies, it is important to understand why habitats require active conservation in the first place. Natural habitats are not static — they exist in dynamic equilibrium, shaped by disturbance, succession, and species interactions. However, human activities have disrupted these dynamics at an unprecedented rate and scale, creating fragmented, degraded landscapes that can no longer support the biodiversity they once held.
Habitat Loss and Fragmentation
When a continuous habitat is divided into smaller, isolated patches by roads,