Tree Quality Vigor Classifier

The Tree Quality Vigor Classifier assigns trees to a classification system based on vigor and stem quality. This classification can then be used as a criterion in other behaviors.

There are four classes (1, 2, 3, 4) for deciduous species and two classes (5, 6) for conifers. The four classes used for deciduous species result from the combination of two possible vigor states and two stem quality levels. For conifers, only vigor is considered. The two vigor status are "vigorous" and "non-vigorous", where non-vigorous trees are considered at high risk of dying before the next harvest. The quality levels are "with sawlog potential" and "without sawlog potential".

Parameters for this behavior

How it works

Tree classification is as follows:

Species are defined as deciduous or coniferous using the Quality Vigor Classifier - Species Type parameter.

Trees that do not have vigor and quality designations, such as new adult trees or initial conditions trees that were not specifically assigned these values, are randomly given vigor and quality according to defined probabilities that these trees are vigorous or of sawlog quality. These probabilities are defined, as values between 0 and 1, in the Quality Vigor Classifier - Prob New Adults Vigorous and Quality Vigor Classifier - Prob New Adults Sawlog parameters. Coniferous species are not assigned a quality value and values entered for those species are ignored.

Vigor and quality for a tree may change through time. The probability of transition between states is a function of previous class and size, and is evaluated for each tree each timestep. The probability of a tree being vigorous in the current timestep is:

where:

where:

• β ₀ is the Quality Vigor Classifier - Vigor Beta 0 parameter
• β _1class is one of the following depending on the current class designation of the tree:
  • Quality Vigor Classifier - Vigor Beta 1 Class 1
  • Quality Vigor Classifier - Vigor Beta 1 Class 2
  • Quality Vigor Classifier - Vigor Beta 1 Class 3
  • Quality Vigor Classifier - Vigor Beta 1 Class 4
  • Quality Vigor Classifier - Vigor Beta 1 Class 5
  • Quality Vigor Classifier - Vigor Beta 1 Class 6
• β ₂ is the Quality Vigor Classifier - Vigor Beta 2 parameter
• β ₃ is the Quality Vigor Classifier - Vigor Beta 3 parameter
• DBH is the tree's DBH in cm

Deciduous trees are further evaluated for tree quality. The probability of a tree being of sawlog quality in the current timestep is:

where:

where:

• β ₀ is the Quality Vigor Classifier - Quality Beta 0 parameter
• β _1class is one of the following depending on the current class designation of the tree:
  • Quality Vigor Classifier - Quality Beta 1 Class 1
  • Quality Vigor Classifier - Quality Beta 1 Class 2
  • Quality Vigor Classifier - Quality Beta 1 Class 3
  • Quality Vigor Classifier - Quality Beta 1 Class 4
• β ₂ is the Quality Vigor Classifier - Quality Beta 2 parameter
• β ₃ is the Quality Vigor Classifier - Quality Beta 3 parameter
• DBH is the tree's DBH in cm

Note that since only deciduous trees get a quality designation, there is no need for β ₁ parameters for classes 5 and 6, which only apply to conifers.

Once a tree's probability of vigorousness and sawlog quality have been established, random numbers determine the final state. Then class assignment proceeds as above.

This behavior creates three tree data members: "Vigorous", "Sawlog", and "Tree class".

How to apply it

Apply this behavior to adults of any species. It cannot be applied to any other life history stage.