Stable natural ecosystems persist when energy flow, nutrient recycling, biodiversity, and abiotic conditions keep populations within recoverable limits over time.
Ecosystem stability is the capacity to maintain characteristic structure and function over time or recover after disturbance.
Resistance limits the immediate effect of disturbance, while resilience is the capacity to recover. Evidence from forests, deserts and other natural ecosystems shows that some recognizable systems have persisted for millions of years.
A forest can undergo seasonal population changes and recover from storms while retaining its nutrient cycling, food-web structure and dominant vegetation over long periods.
Stability means continuity of key properties, not a frozen species count or absence of all change.
Core D4.2 is secure when students can judge whether a system is being stabilized or pushed toward change. The route is: identify the stability support or disturbance, explain the mechanism, and state the ecosystem consequence using evidence.
Core transfer questions ask students to explain why an ecosystem remains stable or why a disturbance pushes it toward change. Strong answers do not list threats; they explain mechanisms such as lost rainfall recycling, trophic cascade, overharvest, nutrient enrichment, toxin biomagnification, plastic movement, or restoration through rewilding.