SORTIE-ND

Software for spatially-explicit simulation of forest dynamics

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NCI size effects

Note: If these effects are used with NCI Mortality, the time period unit for parameters must match the value specified in the NCI Parameter Period (years) parameter.

Default size effect

Parameters

NCI Size Effect Mode, in cm (X0)	The mode of the size effect curve.
NCI Size Effect Variance, in cm (Xb)	The variance of the size effect curve.

How it works

Size Effect is calculated as:

where:

diam is the diameter of the target tree, in cm (d10 for seedlings, DBH for all others)
X₀ is the NCI Size Effect Mode, in cm (X0) parameter
X_b is the NCI Size Effect Variance, in cm (Xb)

Size effect w/ lower bound

Parameters

NCI Size Effect Mode, in cm (X0)	The mode of the size effect curve.
NCI Size Effect Variance, in cm (Xb)	The variance of the size effect curve.
NCI Size Effect Minimum Diameter	The minimum possible diameter for size effect. Trees with a diameter less than this value will use this value in the size effect calculation instead.

How it works

Size Effect is calculated as:

where:

diam is the diameter of the target tree, in cm (d10 for seedlings, DBH for all others)
X₀ is the NCI Size Effect Mode, in cm (X0) parameter
X_b is the NCI Size Effect Variance, in cm (Xb)

You can set a minimum diameter for the size effect in the NCI Size Effect Minimum Diameter parameter. Any target tree whose diameter is less than this value will get a size effect based on the minimum diameter instead. This allows you to avoid problems with very small trees that can occur because of the shape of the lognormal function.

Size effect power function

Parameters

NCI Size Effect "a"	Size effect power function scaling factor "a" parameter.
NCI Size Effect "b"	Size effect exponent "b" parameter.

How it works

Size Effect is calculated as:

SE = a * diam^b

where:

diam is the diameter of the target tree, in cm (d10 for seedlings, DBH for all others)
a is the NCI Size Effect "a" parameter
b is the NCI Size Effect "b" parameter

Size effect shifted lognormal

Parameters

NCI Size Effect Minimum Diameter	The minimum possible diameter for size effect. Trees with a diameter less than this value will use this value in the size effect calculation instead.
NCI Size Effect Mode, in cm (X0)	The mode of the size effect curve.
NCI Size Effect Variance, in cm (Xb)	The variance of the size effect curve.
NCI Size Effect Shift, in cm (Xp)	The amount of peak shift.

How it works

Size Effect is calculated as:

where:

diam is the diameter of the target tree, in cm (d10 for seedlings, DBH for all others)
X₀ is the NCI Size Effect Mode, in cm (X0) parameter
X_b is the NCI Size Effect Variance, in cm (Xb)
X_p is the NCI Size Effect Shift, in cm (Xp)

Size effect compound exponential

Parameters

Size Effect "a"	The "a" parameter in the compound exponential function.
Size Effect "b"	The "b" parameter in the compound exponential function.
Size Effect "c"	The "c" parameter in the compound exponential function.
Size Effect "d"	The "d" parameter in the compound exponential function.

How it works

Size Effect is calculated as:

where:

diam is the diameter of the target tree, IN METERS (d10 for seedlings, DBH for all others)
a is the Size Effect "a" parameter
b is the Size Effect "b" parameter
c is the Size Effect "c" parameter
d is the Size Effect "d" parameter

Size effect shifted lognormal w/ infestation

This size effect features two different sets of parameters, one for healthy trees and one for trees with an infestation of a pest or pathogen.

Parameters

NCI Size Effect Minimum Diameter	The minimum possible diameter for size effect. Trees with a diameter less than this value will use this value in the size effect calculation instead.
NCI Size Effect X0, Uninfested Trees	The mode of the size effect curve, for healthy trees.
NCI Size Effect Xb, Uninfested Trees	The variance of the size effect curve, for healthy trees.
NCI Size Effect Xp, Uninfested Trees	The amount of peak shift, for healthy trees.
NCI Size Effect X0, Infested Trees	The mode of the size effect curve, for trees infested with a pest or pathogen.
NCI Size Effect Xb, Infested Trees	The variance of the size effect curve, for trees infested with a pest or pathogen.
NCI Size Effect Xp, Infested Trees	The amount of peak shift, for trees infested with a pest or pathogen.

How it works

Trees to which this is assigned must also be assigned a behavior that simulates a pest or pathogen outbreak, such as Insect Infestation or Density Dependent Infestation.

Size Effect is calculated as:

where:

diam is the diameter of the target tree, in cm (d10 for seedlings, DBH for all others)
X₀ is either the NCI Size Effect X0, Uninfested Trees or the NCI Size Effect X0, Infested Trees parameter
X_b is either the NCI Size Effect Xb, Uninfested Trees or the NCI Size Effect Xb, Infested Trees parameter
X_p is either the NCI Size Effect Xp, Uninfested Trees or the NCI Size Effect Xp, Infested Trees parameter

Trees which have not yet been marked as infested by the pest/pathogen behavior get the "uninfested" set of parameters; those that are infested get the "infested" set of parameters.

Size effect compound exponential w/ infestation

This size effect features two different sets of parameters, one for healthy trees and one for trees with an infestation of a pest or pathogen.

Parameters

Size Effect "a", Uninfested Trees	The "a" parameter in the compound exponential function, for healthy trees.
Size Effect "b", Uninfested Trees	The "b" parameter in the compound exponential function, for healthy trees.
Size Effect "c", Uninfested Trees	The "c" parameter in the compound exponential function, for healthy trees.
Size Effect "d", Uninfested Trees	The "d" parameter in the compound exponential function, for healthy trees.
Size Effect "a", Infested Trees	The "a" parameter in the compound exponential function, for trees infested with a pest or pathogen.
Size Effect "b", Infested Trees	The "b" parameter in the compound exponential function, for trees infested with a pest or pathogen.
Size Effect "c", Infested Trees	The "c" parameter in the compound exponential function, for trees infested with a pest or pathogen.
Size Effect "d", Infested Trees	The "d" parameter in the compound exponential function, for trees infested with a pest or pathogen.

How it works

Trees to which this is assigned must also be assigned a behavior that simulates a pest or pathogen outbreak, such as Insect Infestation or Density Dependent Infestation.

Size Effect is calculated as:

where:

diam is the diameter of the target tree, IN METERS (d10 for seedlings, DBH for all others)
a is either the Size Effect "a", Uninfested Trees or Size Effect "a", Infested Trees parameter
a is either the Size Effect "b", Uninfested Trees or Size Effect "b", Infested Trees parameter
a is either the Size Effect "c", Uninfested Trees or Size Effect "c", Infested Trees parameter
a is either the Size Effect "d", Uninfested Trees or Size Effect "d", Infested Trees parameter

Trees which have not yet been marked as infested by the pest/pathogen behavior get the "uninfested" set of parameters; those that are infested get the "infested" set of parameters.