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

# Climate and Competition Dependent Neighborhood Survival

This behavior assesses tree survival as a function of mean annual temperature, water deficit, and neighbor adult basal area. For efficiency, it calculates survival rates for cells in a grid and assigns trees the survival probability of the grid cell in which they are found.

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

### Parameters for this behavior

Parameter nameDescription
Climate Comp Dep Neighborhood Surv - AA in the survival function.
Climate Comp Dep Neighborhood Surv - BB in the survival function.
Climate Comp Dep Neighborhood Surv - CC in the survival function.
Climate Comp Dep Neighborhood Surv - DD in the survival function.
Climate Comp Dep Neighborhood Surv - MM in the survival function.
Climate Comp Dep Neighborhood Surv - NN in the survival function.
Climate Comp Dep Neighborhood Surv - Neigh Search Radius (m)Maximum radius to search for crowding neighbors, in meters.

### How it works

This behavior uses the Climate Comp Dep Neighborhood Survival grid to keep track of survival rates. The annual probability of survival for a given species and given grid cell is calculated as:

where:

• Surv is the annual probability of survival
• A is the Climate Comp Dep Neighborhood Surv - A parameter
• B is the Climate Comp Dep Neighborhood Surv - B parameter
• M is the Climate Comp Dep Neighborhood Surv - M parameter
• N is the Climate Comp Dep Neighborhood Surv - N parameter
• C is the Climate Comp Dep Neighborhood Surv - C parameter
• D is the Climate Comp Dep Neighborhood Surv - D parameter
• T is the mean annual temperature in degrees Celsius as entered in the Plot
• T is the water deficit as entered in the Plot
• BAT is the adult total basal area in the neighborhood, in square meters

BAT is the basal area of all adults within the distance from the center of the grid cell set in the Temp Dependent Neighborhood Surv - Neigh Search Radius (m) parameter.

The probability of survival is for a single year. For multi-year timesteps, the timestep survival probability is the annual probability raised to the power of the number of years per timestep.

Trees receive the survival probability calculated for the grid cell in which they are found. A random number is used to determine whether a tree lives or dies.

### How to apply it

This behavior can be applied to seedlings, saplings, and adults of any species.