SORTIE-NDSoftware for spatially-explicit simulation of forest dynamics
This behavior simulates an insect outbreak. It chooses and marks affected trees, allowing other behaviors to make use of this information. The number of affected trees is a function of time since infestation began. The infestation has no spatial pattern.
This behavior only chooses trees for infestation. It does not kill them or alter their dynamics in any way. Other behaviors may take advantage of the infestation status information of trees.
Parameters for this behavior
How it works
The proportion of trees of a particular species infested as a function of time is as follows:
You choose when an infestation begins with the Insect Infestation First Timestep parameter. Infestation ends if it is directed to (using the Insect Infestation Last Timestep parameter) or if there are no more infested trees in the plot. If infestation ends, it does not start again.
You can set a minimum DBH of infestation, using the Insect Infestation Min DBH parameter.
The proportion of trees infested at time T does not depend on additions to or subtractions from the pool of eligible trees. Each timestep, the number of infested trees of each species is counted and additional trees are randomly selected for new infestation until approximately the right number are infested. If for some reason there are more trees infested than there should be at that time, no additional trees are infested.
When selecting trees for infestation, the location of the trees is not considered. It is assumed that all trees have an equal chance of becoming infested no matter where they are in the plot. This behavior uses a tree data member called "Years Infested" to track which trees are infested and how long they have been so.
How to apply it
Apply this behavior to saplings and/or adults of any species.