Density Self-Thinning Mortality
This behavior calculates the probability of mortality of an individual juvenile tree as a function of the density and mean diameter of the neighborhood trees. Only neighborhood seedlings and saplings are taken into account in this behavior.
Trees killed by this behavior will have a mortality reason code of "natural".
Parameters for this behavior
|Density Self-Thinning Asymptote (A)||The asymptote of the density self-thinning function.|
|Density Self-Thinning Density Effect (S)||The parameter controlling the density effect of the density self-thinning function.|
|Density Self-Thinning Diameter Effect (C)||The parameter controlling the effect of neighbor mean diameter of the density self-thinning function.|
|Density Self-Thinning Minimum Density for Mortality (#/ha)||The minimum density of neighbors, in stems/ha, for density self-thinning mortality. A tree with a lower density of neighbors than this value will not die.|
|Density Self-Thinning Neighborhood Radius, in m||The maximum radius, in m, within which to search for neighbors to calculate neighbor density for density self-thinning.|
How it works
The probability of mortality is calculated with a double Michaelis-Menton function:
- Pm is the probability of mortality for an individual tree
- density is the density of neighboring seedlings and saplings, in stems/ha, within a radius defined in the Density Self-Thinning Neighborhood Radius, in m parameter
- diam m is the mean diameter of neighbors, measured 10 cm above root collar in cm
- A is the Density Self-Thinning Asymptote (A) parameter
- C is the Density Self-Thinning Diameter Effect (C) parameter
- S is the Density Self-Thinning Density Effect (S) parameter
If the value of density is less than the value in the Density Self-Thinning Minimum Density for Mortality (#/ha) parameter, the tree does not die.
How to apply it
This behavior can be applied to seedlings and saplings of any species. It cannot be applied to adults. This behavior can only be applied with a one year timestep.