Seed Bank Pulse: Disturbance & Germination Simulator

Disturbance

Gap radius 4 cells

Severity 70%

Or click / tap anywhere on the plot to open a canopy gap right there.

Seed Bank Physiology

Viability decay rate 0.08 / yr

Germination sensitivity 0.25 / yr

Live Readouts

Seed bank (avg)0 /m²

Canopy cover0%

Germination flux0 /m²/yr

Simulated time0.0 yr

How it works

Every soil cell carries two coupled state variables: the dormant seed bank S (seeds/m²) and the canopy cover C (0–1, fraction of full shade). Each simulated year they evolve as:

Light at soil surface:  L = 1 − C
Viability decay:        dS/dt = −k_d · S
Germination pulse:      dS/dt −= g · S · L
Canopy regrowth:        dC/dt = r · C·(1−C)  +  a · (germinated seeds)
Seed rain (mature C):   dS/dt += p · max(0, C − C_mature)

With a closed canopy (C→1, L→0) almost nothing germinates even though the seed bank is full — light, not seed supply, is the bottleneck. A disturbance instantly removes canopy in a radius around its epicentre (linear fall-off to the edge) and — the more severe it is — also burns/erodes a share of the local seed bank itself, exactly like a real fire consumes topsoil seeds while a light thinning barely touches them. The light spike that follows triggers a germination pulse in the following seasons, visible as the pale seed-bank dots draining while the green canopy pillars regrow from the gap outward. Once regrown trees mature past the threshold C_mature they start dropping seed again, slowly refilling the bank for the next disturbance cycle — the same replenish/deplete loop that governs real post-fire and post-logging forest recovery.

Gap radius / Severity — set how large and how destructive the next disturbance is.
Viability decay — how fast ungerminated seeds lose the ability to sprout while waiting underground.
Germination sensitivity — how strongly a given light level converts standing seed bank into seedlings per year.

Canopy cover (height) Dormant seed bank

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