Tree Replacement Guidelines

What trees are required to be replaced?

• Publicly-owned trees, such as street trees or park trees.
• Trees in Resource Protection Areas
• Trees on development projects that have permit conditions requiring replacement (such as 4.1 site plans).

Trees on private property, and in by-right development projects are not typically required to be replaced according to this formula (except as outlined in Private Tree Care and Removal Permits), but other tree canopy coverage requirements may still apply.

How does tree replacement get calculated?

An evaluation of potential tree loss will be made prior to removals to determine if the proposed trees represent reasonable compensation for the total value of trees removed. To assist in that evaluation the following criteria shall be used:

• All alive trees between 3 and 10 inches diameter are replaced 1:1
• All alive trees above 10 inches diameter are replaced according to Diameter X Species Rating X Condition

Definitions:

Diameter: Trunk diameter at four and one half feet above the ground.

Species Rating: All tree species are given a value from 1 to 100 which is expressed as a percentage of 100 (e.g. 40 = 40% = .4). This is a value assigned to a species according to a number of factors including longevity, durability and appropriateness to the growing zone, , according to the guide available here: https://www.mac-isa.org/images/pdfs/Speciesratings2021.pdf

Condition: Rating from 0 (dead) to 100% (perfect), expressed as a percentage of 100 (e.g. 100% = 1, 60% = .6), according to the most recent edition of the per the Guide for Tree Appraisal, 10th Edition, (or most recent edition), by the Council of Tree and Landscape Appraisers.

Trees over 10 inches are replaced at the following rates, based on the overall scores:

• 1-4.9 = one tree
• 5-9.9 = two trees
• 10-14.9 = three trees
• 15-19.9 = four trees
• 20-24.5 = five trees
• 25+ = six trees

How do I replace trees, and how are they counted?

Planted trees are being counted as follows:

• Replacement Value: One-for-One Basis: One new shade tree or large/medium-large/medium evergreen tree shall fulfill the replacement requirement of one replacement tree per the tree replacement calculations.

• Replacement Value: Three-to-One Basis: Three deciduous ornamental or small/ small-medium evergreen trees shall fulfill the replacement requirement of one replacement tree per the tree replacement calculations.

See our recommended trees listsfor guidance. and determination of size.

Conditions:

• The original species does not influence the amount of tree replacements. For example, if an ornamental tree requires 1 replacement, that replacement must be 1 shade tree or large evergreen tree, or 3 ornamental or small evergreen trees.
• Public trees: Appropriate species, quantities and sizes must follow Administrative Regulation 4.3 and its addenda.
• Private trees: must follow the recommended tree list

What if I cannot replace all trees on my project?

Payment into the Tree Canopy Fund or Stormwater fund may be an option for your project. Check your project's permit conditions or ask the urban forestry office for guidance at urbanforestry@arlingtonva.us 

Examples 

For example:

• 1. A 10-inch American holly is automatically replaced with one tree, according to the above policy.
• 2. A 40-inch silver maple (species rating of 40), rated at 60 percent condition, is scored as 40 X .4 X .6 for a total score of 9.6.
• 3. A 36-inch white oak (species rating of 80), rated at 70 percent condition, is scored as 36 X .8 X .7 for a total score of 20.16.

In the examples above, the American holly is replaced with one tree, the silver maple with two trees and the white oak with five trees.

The formula should only be used by qualified individuals, like professional arborists, with the knowledge of tree condition determinations and species factors.

Example 1 - Tree inventory - Replacement calculations

Note: The diameters with an asterisk (*) denote trees with 10 inches DBH and smaller, which are automatically replaced at a rate of one-for-one according to the policy.

Example 2 - Tree inventory - Replacement calculations

Note: The diameters with an asterisk (*) denote trees with 10 inches DBH and smaller, which are automatically replaced at a rate of one-for-one according to the policy.

Example 3 - Tree planting plan