Five species share a reserve landscape. Each population follows logistic growth toward a carrying capacity set by local habitat quality and landscape connectivity, minus mortality from poaching pressure. A central protected zone (radius set by the Protected Area slider) keeps high habitat quality; land outside it is degraded. Fragmentation scatters barrier blocks that cut corridors, hurting wide-ranging species (predators, herbivores) more than mobile ones (pollinators).
dN_i/dt = r_i * N_i * (1 - N_i/K_i) - (T/100) * s_i * N_i
K_i = K0_i * Qavg * [1 - (1-C)*min(c_i,1.4)/1.4]
H = -Σ p_i ln(p_i), p_i = N_i / ΣN (Shannon diversity)
- Protected Area - enlarges the high-quality reserve core, raising Qavg and every species' carrying capacity K_i.
- Habitat Fragmentation - reduces connectivity C, cutting K_i most for species with high corridor-sensitivity c_i (predators, herbivores).
- Threat Pressure - adds direct mortality T·s_i·N_i on top of natural dynamics, driving weak populations toward local extinction (N_i < 1).
Real reserves (e.g. wildlife corridors linking national parks) use exactly this logic: protecting core habitat, restoring connectivity, and reducing poaching all raise the Shannon index and buffer against collapse.