Seed Dispersal

Overview

Seed dispersal is an additional constraint on species establishment that only allows species to establish in a cell seeds are present. This module is a fantastic way to simulate recovery after disturbance events or, coupled with colonization, can be used to simulate a colonizing species entering the simulation.

Seed dispersal is only available in gridded mode.

Turning on Seed Dispersal

Seed dispersal must be turned on first at the simulation level in the grid setup file. If this step is not taken seed dispersal will not be used at all.

Seed dispersal is then turned on at the species level in the species.in file.

Customizing Seed Dispersal

The parameters for the seed dispersal algorithm are also input in the species.in file. Remember that these values are only relevant if the associated species is turned on for seed dispersal and seed dispersal is turned on for the simulation.

Seed Dispersal Output

A description of the output options for seed dispersal can be found here.

Note on Seed Dispersal

Seed dispersal is particularly sensitive to initial conditions. Remember that the only way for a species to establish in a given cell is by receiving seeds from a nearby cell, and every simulation begins with no species established. This means that without some intervention a species with seed dispersal turned on will never establish.

There are two ways of overcoming this problem:

Use Spinup to allow the species to establish before seed dispersal is turned on. This is your best bet to ensure the species will have mature individuals ready to disperse seeds when the simulation begins.
Use colonization to establish the species any time during the simulation. Using colonization can turn the problem of establishing the first individuals to your advantage because it guarantees that no individuals will establish early. For example, if you would like to simulate a species colonizing in the middle of a simulation you can create a colonization event for that species to allow the first individual(s) to establish then let seed dispersal do the rest.