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

# Linear bi-level growth

This behavior increments growth according to a simple linear equation, with the possibility of two sets of parameters for each species: one for high-light conditions and one for low-light conditions. This can also be used alone without the light levels.

### Parameters for this behavior

Parameter nameDescription
Linear Bi-Level - Intercept for High-Light Growth (a)The intercept of the linear growth function used in high-light conditions.
Linear Bi-Level - Intercept for Low-Light Growth (a)The intercept of the linear growth function used in low-light conditions.
Linear Bi-Level - Slope for High-Light Growth (b)The slope of the linear growth function used in high-light conditions.
Linear Bi-Level - Slope for Low-Light Growth (b)The slope of the linear growth function used in low-light conditions.
Linear Bi-Level - Threshold for High-Light Growth (0 - 100)The threshold between low-light and high-light parameters, as a value between 0 and 100.

### How it works

The equation used by this behavior to increment growth is:

Y = (a + b * diam) * T

where

• Y = amount of diameter growth in cm
• a = growth intercept; in high-light conditions, this is the Linear Bi-Level - Intercept for High-Light Growth (a) parameter; in low-light conditions, this is the Linear Bi-Level - Intercept for Low-Light Growth (a) parameter
• b = growth slope; in high-light conditions, this is the Linear Bi-Level - Slope for High-Light Growth (b) parameter; in low-light conditions, this is the Linear Bi-Level - Slope for Low-Light Growth (b) parameter
• diam = diameter (diameter at 10 cm for seedlings and saplings, DBH for adults)
• T = number of years per timestep

Light levels come from the Storm Light grid produced by the Storm Light behavior. The threshold between the use of high-light and low-light parameters is set in the Linear Bi-Level - Threshold for High-Light Growth (0 - 100) parameter.

This behavior can also be used without Storm Light. In this case, only the low-light growth parameters are used.

### How to apply it

This behavior can be applied to seedlings, saplings, and adults of any species. If you wish to use the light-level parameter switch, also use the Storm Light behavior. You can use either the diam with auto height or diam only version.