Arboriculture

Understanding the Tampa Tree Table

2020-10-17

The City of Tampa “Tree Table” is used to establish the number and size of trees that shall be used to calculate mitigation or protected, specimen, and grand trees. It is also known as Table 284.4.1-A: Tree Retention-Mitigation Equivalency Tables by Tree Type. When trees are proposed for preservation or removal, they are translated into a system of credits and debits that yield a total number of replacement trees when required.

Needed to Complete the Tree Table

  • A tree survey, showing tree location, diameter at breast height (dbh), and tree species
  • The disposition of each tree, whether it will be preserved, removed, or relocated.
sabal palms in a cleared forest

Each tree’s dbh determines how many credits or debits are applied to the preservation or removal of that tree. The dbh also determines whether the tree is considered grand or not.

The species of the tree determines the category of the tree that is credited or debited. The types of trees conform with the Florida Department of Agriculture and Consumer Services (FDACS) Florida grades and Standards (FGS) for Nursery Plants (specifically the 2017 revision). FGS identifies four categories:

Type 1 – Tall & Wide

Type 2 – Tall & Narrow

Type 3 – Short/Wide-Multi-Stem

Palms.

Florida Grades and Standards 2017.1

Mitigation Calculations

If the tree is a protected or specimen tree, then the credit or debit calculation is calculated using an integer multiplier. However, if the tree is grand, several additional data elements are necessary to calculate credits or debits.

For grand trees mitigation, mitigation is calculated by canopy area replacement. Several factors are considered in this calculation, including growth rate, tree type, condition rating, dbh, crown diameter, and species rating. The growth rate is held constant at “moderate” for all trees. The condition rating and species rating are both diminution multipliers that are applied to an approximate crown footprint. The adjusted crown footprint is then multiplied by a unit-tree value to yield a credit or debit that is incorporated into the protected and specimen tree calculations.

Anytime a tree exists on a site subject to site permitting requirements, a tree table is required. The city has provided excel tables to assist residents and developers in preparing the required Tampa Tree Table.

"Tree Blender"

To improve the calculation and reporting of larger inventories, Dark Moss created a proprietary tree assessment protocol. The cloud-based program allows our inventory team to gather the exact information needed to identify grand trees, populate the tree table, report useful urban forest statistics, and satisfy permitting requirements. We also aspire to create visually pleasing and useful reporting documents, so we created our own improved version of the Tampa Tree Table.

Tree Types for Tree Species Identified in the 2016 Canopy Study