Ecosystems under stress

Ecosystems under stress explores how natural ecosystems respond to pressures, both natural and human-induced. This topic is central to AQA A-Level Geography as it connects physical geography (biomes, nutrient cycles) with human geography (resource exploitation, conservation). You'll study the concept of resilience—how ecosystems absorb disturbance—and thresholds beyond which they may collapse. Key case studies include tropical rainforests (e.g., Amazon deforestation) and coral reefs (e.g., Great Barrier Reef bleaching), illustrating the fragility of these systems under climate change and direct human impacts.

Understanding ecosystems under stress is vital because it reveals the consequences of unsustainable resource use and informs strategies for management. The topic builds on earlier knowledge of biomes and succession, but now focuses on dynamic change and tipping points. You'll evaluate concepts like the 'Tragedy of the Commons' and sustainable development, linking to global governance issues. This knowledge is directly applicable to contemporary debates about biodiversity loss, climate mitigation, and the UN Sustainable Development Goals.

In the AQA exam, this topic appears in Paper 1 (Physical Geography) and can be integrated into essays on hazards or global systems. Mastery requires not just memorising case studies but applying theoretical frameworks—such as the resilience theory of Holling—to explain why some ecosystems recover while others shift to new states. Expect data response questions on graphs showing species decline or biomass changes, so practise interpreting trends and linking them to stressors like pollution or overfishing.