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

# Conspecific Tree Density Dependent Seed Survival

This behavior assesses seed survival as a function of the local density of conspecific trees. This behavior is very similar to Density Dependent Seed Survival.

### Parameters for this behavior

Parameter nameDescription
Conspecific Tree Minimum Neighbor Height (m)The minimum height, in meters, of conspecific neighbors to include in local density calculations.
Conspecific Tree Search Radius (m)The radius, in meters, to search for conspecific neighbors to include in local density calculations.
Slope of Density DependenceThe slope of the density dependence function for determining how many seedlings establish per square meter (c in the equations below).
Steepness of Density DependenceThe steepness of the density dependence function for determining how many seedlings establish per square meter (δ in the equations below).

### How it works

This behavior takes the seeds that have been dispersed to each grid cell of the Dispersed Seeds grid and calculates how many will survive. The survival probability is a function of the density of conspecific neighbors.

The density of conspecific neighbors is the number of stems per square meter of trees above the height set in the Conspecific Tree Minimum Neighbor Height (m) parameter, within the radius set in the Conspecific Tree Search Radius (m) parameter.

The number of seeds that survives is calculated as

Rsp = Ssp * exp(-c * Denspδ )

where:

• Rsp is the number of surviving seeds of a given species in the seed grid cell
• Ssp is the original number of seeds of that species in that grid cell
• Densp is the density of conspecific neighbors (number per square meter) of that species in that grid cell
• c is the Slope of Density Dependence parameter
• δ is the Steepness of Density Dependence parameter

Once the number of surviving seeds has been determined, the behavior assigns that number back to the Dispersed Seeds grid cell.

### How to apply it

Apply this behavior to seeds of your desired species. Any species to which it is applied must also have any disperse behavior applied.