Trunk Formula Valuation Method

The Trunk Formula Method is used to appraise the monetary value of trees that are considered too large to be replaced with nursery or field-grown stock. The value of the tree is based on the cost of the largest commonly available transplantable tree and the cost to install it, plus the increase in value due to the larger size of the tree being appraised. As with the Replacement Cost Method, the Basic Tree Cost is adjusted according to species of the tree, its physical condition, and its landscape location (site, contribution, and placement).

For information on how to value a tree using the Trunk Formula method, a step-by-step approach, and example are available.  A color-coded sample of the Valuation tab using the Trunk Formula Method appears below:

To calculate the value of your tree using the Trunk Formula Valuation Method, complete the steps below:

1. Begin with the Structure and Health section.  This section appears within the yellow box at the left-hand side of the screen above.
   • Enter structure and health values in the fields shaded in yellow.  The values entered will need to be on a scale of 1-4 with 4 being the highest.
   • The system calculates the subtotals and Condition Rating in the white fields above.
2. Next, you will move to the Shared Valuation Fields in the center of your screen.  These fields appear within the green box above.
   • The Species Factor in the pink field will be carried over from the Tree Code Setup module.
   • The Condition Factor in the yellow field will be carried over from the Structure and Health section.
   • Enter a dollar amount in the Installation Cost and Replacement Cost fields. These fields are shaded in green above
   • Enter a percentage in the Site Factor, Contribution Factor, and Placement Factor in the fields shaded in green above.
   • The Location Factor field in white will be calculated by the system.  This represents the average value of the Site Factor, Contribution Factor, and Placement Factor percentage fields.  The system calculates this value using the formula below:

     Location % = (Site % + Contribution % + Placement %)/3

3. Finally, you can calculate the Trunk Formula Valuation.  This last step appears in the blue box on the right-hand side of the screen above.
   • Enter the Replacement Diameter of the new tree in the field shaded in blue.  The white field to the right will be calculated by the system.
   • The Installed Tree Cost shaded in green will be carried over from the Shared Valuation Fields.
   • The Unit Tree Cost will be calculated by the system.
   • Enter the Appraised Diameter of the tree being replaced in the field shaded in blue.  The white field to the right will be calculated by the system.
   • The Trunk Increase will be calculated by the system.
   • The Basic Tree Cost will be calculated by the system using the formula below:

     Basic Tree Cost = Trunk Area Increase of the appraised tree * Unit Tree Cost + Installed Tree Cost

   • The Trunk Form Value will be calculated by the system using the formula below:

     Trunk Form Value = Basic Tree Cost * Species % * Condition % * Location %