Introduction
Biodiversity—the variety of life at genetic, species, and ecosystem levels—is a cornerstone of IB Environmental Systems and Societies (ESS). In the 2026 syllabus, biodiversity is emphasized as both an ecological foundation and a human necessity.
Examiners test biodiversity across multiple topics, from ecosystems and succession to conservation and sustainability. ESS students must understand not only what biodiversity is, but also why it matters and how it connects to human well-being and environmental stability.
Quick Start Checklist: Why Biodiversity Matters
- Maintains ecosystem stability and resilience.
- Provides ecosystem services (food, water, pollination, climate regulation).
- Supports genetic diversity, crucial for adaptation.
- Holds cultural, ethical, and economic value.
- Human impacts threaten biodiversity, requiring conservation strategies.
- Tested in case studies, data analysis, and evaluation essays.
Ecological Importance of Biodiversity
- Stability and Resilience: Diverse ecosystems can better recover from disturbances like fire or drought.
- Ecosystem Services: Biodiversity underpins services like pollination, water purification, and nutrient cycling.
- Food Webs: Rich biodiversity ensures complex food webs that support balanced energy flows.
Human Dependence on Biodiversity
Biodiversity is not just a natural asset—it directly affects societies:
- : Crops and livestock rely on genetic diversity for resilience against pests and disease.
