Introduction
Ecosystems are at the heart of IB Environmental Systems and Societies (ESS). With the new syllabus first assessed in 2026, ecosystems are not just background knowledge—they form the foundation for understanding energy flows, biodiversity, human impacts, and sustainability strategies.
But which ecosystems do you actually need to know for exams? The good news: ESS does not expect you to memorize every ecosystem on Earth. Instead, you need a clear understanding of key types of ecosystems and biomes, along with case studies you can apply flexibly in exam questions.
Quick Start Checklist: ESS Ecosystems
- Study major global biomes (tropical rainforest, desert, tundra, grasslands, temperate forest, aquatic ecosystems).
- Know local ecosystem examples from your own country or region.
- Understand energy flows and food webs within these systems.
- Learn how succession and disturbances affect ecosystems.
- Be ready to discuss human impacts and conservation strategies.
- Use case studies to support exam answers.
Major Ecosystems in the ESS 2026 Syllabus
1. Terrestrial Biomes
- Tropical Rainforest: High biodiversity, nutrient cycling, deforestation issues.
- Desert: Adaptations to water scarcity, fragile balance, desertification risks.
- Savanna/Grasslands: Seasonal rainfall, agriculture vs conservation trade-offs.
- Temperate Forest: Rich soils, deforestation for farming and urban use.
- Tundra: Permafrost, climate change vulnerability.
2. Aquatic Ecosystems
- Freshwater ecosystems: Rivers, lakes, wetlands—important for water management.
- Marine ecosystems: Coral reefs, coastal zones, open ocean—biodiversity hotspots but threatened by pollution and overfishing.
Local Ecosystems
Examiners encourage students to use local examples. For instance, a UK student might study heathlands or chalk grasslands, while a student in Kenya might focus on savannas. Using personal case studies shows application beyond textbook examples and earns higher marks.
What You Need to Know About Each Ecosystem
For each ecosystem, be prepared to explain:
- Energy flows (producers, consumers, decomposers).
- Nutrient cycling (carbon, nitrogen, water).
- Population dynamics (carrying capacity, limiting factors).
- Succession stages and how disturbances (fires, human activity) change systems.
- Human impacts such as agriculture, urbanization, or pollution.
- Conservation strategies like protected areas, restoration, and sustainable management.
Ecosystems and Systems Thinking
Ecosystems are the perfect setting to practice systems thinking. For example, studying a mangrove forest means looking at:
- The ecological role (habitat, coastal protection).
- The economic role (fisheries, tourism).
- The social role (local livelihoods).
- The impact of disturbances (deforestation, climate change, rising sea levels).
Conclusion
In IB ESS 2026, you need a working knowledge of major global biomes, aquatic ecosystems, and local examples. The key is not just memorizing facts, but applying them in a systems-thinking framework that connects energy, biodiversity, human activity, and sustainability.
By mastering ecosystems, you’ll be well-prepared to tackle a wide range of exam questions, from Paper 1 data responses to Paper 2 essays.
Call to Action
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