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

# Gompertz Density Self Thinning Mortality

This behavior calculates the probability of mortality of an individual tree as a function of the density of conspecific neighborhood trees.

Trees killed by this behavior will have a mortality reason code of "natural".

### Parameters for this behavior

Parameter nameDescription
Gompertz Density Self Thinning - GG in the function for probability of mortality.
Gompertz Density Self Thinning - HH in the function for probability of mortality.
Gompertz Density Self Thinning - II in the function for probability of mortality.
Gompertz Density Self Thinning - Min Neighbor Height (m)Minimum height for conspecific neighbors to be counted towards density.
Gompertz Density Self Thinning - Neighbor Search Radius (m)Radius for which to search for conspecific neighbors.

### How it works

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 from the target tree's location set in the Conspecific Tree Search Radius (m) parameter.

The probability of mortality is calculated as follows:

Pm = G * exp(-exp(H - I * Den))

where:

• Pm is the probability of mortality for an individual tree
• Den is the density of conspecific neighbor trees, stems/m2
• G is the Gompertz Density Self Thinning - G parameter
• H is the Gompertz Density Self Thinning - H parameter
• I is the Gompertz Density Self Thinning - I parameter

### How to apply it

This behavior can be applied to trees of any species.