SORTIE-ND
Software for spatially-explicit simulation of forest dynamics

# Substrate Dependent Seed Survival No Gap Status

This behavior assesses seed survival based on substrate conditions.

### Parameters for this behavior

Parameter nameDescription
Fraction Seeds Germinating on Canopy Decayed LogsThe proportion of those seeds that land on decayed logs under canopy conditions that survive to become seedlings. Expressed as a value between 0 and 1.
Fraction Seeds Germinating on Canopy Fresh LogsThe proportion of those seeds that land on fresh logs under canopy conditions that survive to become seedlings. Expressed as a value between 0 and 1.
Fraction Seeds Germinating on Canopy Forest Floor LitterThe proportion of those seeds that land on forest floor litter under canopy conditions that survive to become seedlings. Expressed as a value between 0 and 1.
Fraction Seeds Germinating on Canopy Forest Floor MossThe proportion of those seeds that land on forest floor moss under canopy conditions that survive to become seedlings. Expressed as a value between 0 and 1.
Fraction Seeds Germinating on Canopy Scarified SoilThe proportion of those seeds that land on scarified soil under canopy conditions that survive to become seedlings. Expressed as a value between 0 and 1.
Fraction Seeds Germinating on Canopy Tip-UpThe proportion of those seeds that land on tip-up mounds substrate under canopy conditions that survive to become seedlings. Expressed as a value between 0 and 1.

### How it works

The behavior takes the substrate composition of each grid cell in the Substrate grid and converts it into a single number for each species, called the substrate favorability index. The favorability index is the sum of the proportions of each substrate multiplied by the proportion of seeds that germinate on that substrate. This index represents the proportion of total seeds of that species that are expected to survive in that area of the plot. This index is stored in the grid Substrate Favorability. (In the parameters list, the proportions used are the canopy proportions.)

The behavior then goes through each grid cell in the Dispersed Seeds grid and assesses the survival for the seeds of those species to which it applies. This behavior starts by giving each seed a random temporary location within the Dispersed Seeds grid cell. Then, it retrieves the substrate favorability at that point from the Substrate Favorability grid. It then compares a random number to the substrate favorability to determine whether the seed lives. This method ensures that we can assess substrate favorabilities correctly when the Dispersed Seeds and Substrate grids have different grid cell resolutions.

Once this process is complete, the number of surviving seeds for each species is assigned back to the Dispersed Seeds grid.

### How to apply it

This behavior may be applied to seeds of any species. A species to which this is applied must also have a Disperse behavior applied. Also, the Substrate behavior must be used in the run.