Biodiversity Protection Simulator

Reserve Design

Reserve radius 60 ha-eq

Open corridors 1 / 3

Edge degradation 30%

Poaching pressure 15%

Outcomes

Species richness (S)

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Effective pop. Nₑ

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Extinction risk, 100 yr

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How it works

Reserve area follows the classic species–area relationship: bigger reserves hold more species on a power-law curve, not a straight line. Edge degradation shrinks the effective habitat that actually supports species (forest edge is drier, hotter, more exposed to predators and people). Corridors reconnect outlying fragments to the core, adding their area and letting individuals disperse between patches — the "rescue effect" that buffers against local die-offs. Poaching pressure removes individuals directly, cutting the effective breeding population Nₑ. Extinction risk comes from population viability theory: small populations drift to zero faster under environmental noise, and Nₑ below roughly 50 crosses into severe inbreeding-depression territory (the "50/500 rule" of conservation genetics).

S = c · A_eff^z                  (species–area, z≈0.27)
A_eff = A·(1−deg)·(1 + 0.18·corridors)
Nₑ = D·A_eff·(1−poach)·inbreed(Nₑ)
σ² = σ0²·(1 + deg + poach)
T̄ = 2·Nₑ / σ²                    (Lande 1993 diffusion approx.)
P(extinct, 100 yr) = 1 − e^(−100/T̄)

Reserve radius — the core protected area's size; area grows with the square of radius, so small increases near the minimum pay off disproportionately in species richness.
Open corridors — how many of the three outlying fragments are actively linked to the core by a wildlife corridor; each link adds usable area and dispersal, not just cosmetic acreage.
Edge degradation — how much of the reserve's edge zone is compromised by adjacent land use; higher values shrink effective area and raise year-to-year population variance.
Poaching pressure — added mortality from hunting/trapping; it removes breeding individuals directly and, once Nₑ is small, triggers extra genetic risk (50/500 rule).

Real-world relevance: reserve designers use exactly this trio — area, connectivity and edge/threat management — to size and shape protected areas, because doubling a reserve's nominal area does far less for long-term persistence than closing one missing corridor once a population has fallen near its minimum viable size.

Core reserve Open corridor Degraded matrix Focal species Species marker

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