Five populations (producers, pollinators, herbivores, predators, and decomposers — shown as
distinct shapes/colors) share one biome. Habitat quality sets overall carrying capacity, disturbance
disproportionately hits sensitive species (predators, pollinators), and invasive pressure crowds out
native populations one by one, driving richness down even while total headcount can stay high.
Shannon index: H' = −Σ pᵢ·ln(pᵢ) (pᵢ = species i share of total population)
Evenness: E = H' / ln(S) (S = species richness)
Extinction: species i → 0 when its capacity share falls below a survival threshold
- Habitat quality — raises overall carrying capacity for every species, most for predators and pollinators.
- Disturbance level — thins sensitive species fastest; high disturbance can locally extinguish predators first.
- Invasive species pressure — displaces native populations, driving richness down even if total biomass is stable.
- Protect habitat — instantly improves habitat quality and cuts disturbance to simulate a conservation intervention.
Real-world relevance: conservation biologists track Shannon diversity exactly this way to
detect when an ecosystem is quietly losing resilience — total abundance can look fine while a few
sensitive species are already gone.