AP Syllabus focus:
‘Ecosystems with fewer component parts and little diversity are often less resilient to environmental change.’
Ecosystem resilience depends strongly on biodiversity. Diverse ecosystems typically resist disturbance better and recover faster because multiple species and interactions can buffer change when conditions shift.
What “diversity” means in this context
Biodiversity can refer to the variety of living components present and how evenly they are represented. In this subtopic, the key idea is that having more component parts (species, functional roles, interactions) generally improves ecosystem performance when environments change.
Core idea from the syllabus
Ecosystems with fewer component parts and low diversity tend to be less resilient when faced with environmental change (for example, temperature shifts, drought, altered nutrient inputs, storms, or new pathogens).
Resilience and environmental change
Practice Questions
FAQ
Common approaches include measuring recovery time to a predefined threshold, the magnitude of functional change during disturbance, and variability through time.
Yes. If the disturbance targets a shared vulnerability (e.g., all species are temperature-sensitive), high richness may not prevent large declines.
Rare species can act as “insurance” if they tolerate conditions that reduce dominants, but their contribution depends on whether they can increase quickly after disturbance.
Patchiness can create refuges where organisms persist during disturbance, aiding recolonisation afterwards and improving system-level recovery.
Resilience can depend on disturbance frequency and long recovery periods; short studies may miss delayed effects, feedbacks, or slow compensation among species.
