Defaunation & Seed Dispersal Collapse (2D Forest Plot)

Defaunation Pressure

Hunting / habitat pressure 0%

Large-seeded tree share 33%

Simulation speed 1.0×

Live Readouts

Large-seed recruit rate0.0 / min

Mean dispersal distance0.0 m

Recruit diversity (H)0.00

Legend

Small-seeded tree / recruit Medium-seeded tree / recruit Large-seeded tree / recruit Small frugivores (birds) Medium frugivores (mammals) Large frugivores (tapirs/hornbills)

How it works

Each active animal disperses seeds from trees whose seed class it can physically swallow (gape/body size sets an upper limit, not a lower one). Dispersal distance is drawn from an exponential kernel:

P(d) = (1/λ) · e^(-d/λ)
λ = mean dispersal distance of the disperser
   (set by gut retention time × travel speed)

Small birds carry only small seeds a short way; large frugivores (tapirs, hornbills, large primates) are the only vectors that move large seeds far from the parent tree.

A seed that lands too close to its parent dies from the Janzen-Connell effect — host-specific pests and pathogens concentrate under the parent canopy, so density-dependent mortality is highest right where seeds fall without a disperser:

survive only if d > escape radius(seed class)
germination probability ∝ e^(-crowding × k)

Hunting / habitat pressure removes large-bodied frugivores fastest — they breed slowly, need large ranges, and are preferentially targeted by bushmeat hunting — while small birds are barely affected:

population(species) = base × (1 − pressure × vulnerability)
vulnerability: small 0.2 · medium 0.6 · large 1.0

Push the slider up and large-seeded trees keep flowering but stop recruiting — the real phenomenon field ecologists call "empty forest syndrome": a forest that looks intact from above but has lost the animals that regenerate it. Drag the map to pan, scroll/pinch to zoom; the strip below tracks recruit rate and diversity over time.

Trees: 0 Active frugivores: 0/0 Recruits: 0

drag to pan · scroll to zoom

large-seed rate/min diversity H