Atlanta has adopted a Tree Protection Ordinance (Chapter 158, Division 1, Sections 158-26 through 158-110) to ensure that there will be no net loss of trees in the city. It’s important that all property owners understand the requirements of the law as they make plans for renovation and landscaping of their property.
As a quick reference to assist neighborhood residents, the Parks Committee of NPU-F presents an overview of the law below. A full copy of the law along with relevant definitions can be found at www.atlantaga.gov. Follow the links to “Code of Ordinances” and search for Chapter 158 Vegetation.
See also “How to spot a dangerous tree”
If after reading this material you have additional questions, please feel free to contact any of the following individuals
- Stephanie Coffin, NPU-F Parks Chairperson: 404-874-0523, firstname.lastname@example.org
- Frank Mobley, City of Atlanta Arborist: 404-330-6874
- Linda Austin, Clerk, Tree Conservation Commission: 404-330-6070
The City has implemented its Tree Protection Ordinance because it is the policy of the city that there shall be no net loss of trees within the boundaries of the city. If you’ll keep this in mind as you make your plans, you’ll understand the reasons for their requirements.
In order have no ‘net loss’ of trees, property owners are required to protect the trees that exist on their land, and those that exist on the boundaries of their land. If they’re planning construction, then they must be sure that existing trees are documented and protected during construction.
If the city determines that a tree can be removed, then they must either replace those trees on their land with an equivalent tree or trees, or contribute to the “Tree Trust Fund” (Section 158-66) which collects money to be used for protecting, maintaining, and regenerating trees and other forest resources in Atlanta.
This fund is derived and administered independent of the city budget. Recompense from two sources creates the fund. The first source of funds is from developers, builders, contractors, and homeowners who remove or destroy trees illegally. The second source of the funds is from permitted removal or destruction. When developers, builders, contractors, homeowners, and others cannot meet the standards for tree replacement on their property, they contribute to the fund.
In order to receive a building permit for new construction or renovation, the city requires a number of things related to the trees on your property. Your site plan must indicate the following existing items :
- trees on the property (species, size, location) >= 6″ diameter at breast height
- boundary trees
- topography at 2′ contour intervals
- buildings and structures
- driveways and parking areas
- drainage structures
- water detention areas
Your site plan must also indicate the following proposed and construction related items.
- tree protection fences for trees on site
- tree protection for boundary trees
- proposed topography
- proposed buildings and structures
- proposed driveways and parking areas
- proposed drainage structures
- proposed water detention areas
- construction plan for utilities placement
- construction material staging grounds
- construction limit line
Sec. 158-28. Policy, purpose, and intent.
It is the policy of the city that there shall be no net loss of trees within the boundaries of the city. The purpose of this article is to establish the standards necessary to assure that this policy will be realized and that the city will continue to enjoy the benefits provided by its urban forest. The provisions of this article are enacted to:
- Establish and maintain the maximum amount of tree cover on public and private lands in the city by prohibiting the destruction and removal of trees except in accordance with the standards set forth in this article;
- Maintain trees in the city in a healthy and nonhazardous condition through professionally accepted arboricultural practices;
- Establish and revise as necessary standards for the planting and maintenance of trees so as to improve the economic base of the city by improving property values, to enhance the visual quality of the city and its neighborhoods and to improve public health by lessening air pollution and the incidence of flooding(.)
Sec. 158-26. Definitions. (selected)
Boundary tree means a tree on adjacent property whose tree save area introduces across the property line of the site under consideration.
Buildable area means that area of the lot available for the construction of a dwelling and permissible accessory uses after having provided the required front, side, rear [setbacks] and any other special yards required by part 15 or part 16 of the city code.
Destroy means any intentional or negligent act which will cause a tree to die within a period of five years, as determined by the city forester or city arborist. Such acts include, but are not limited to, cut or fill grade changes that affect more than 20 percent of the tree save area; severing or exposing of the roots in more than 20 percent of the tree save area; trenching across or otherwise severing more than 20 percent of the structural root plate; cutting, girdling, or inflicting other severe mechanical injury to the trunk, roots, or other vital sections of the tree; removal in excess of 20 percent of the live crown of the tree; damage inflicted upon the root system of a tree by the application of toxic substances, including solvents, oils, gasoline and diesel fuel; damage cause by the operation of heavy machinery; damage caused by the storage of materials; and damages from injury or from fire inflicted on trees which results in pest infestation.
Diameter at breast height means the diameter of the main stem of a tree or the combined diameters of a multi-stemmed tree as measured 4.5 feet above the natural grade at the base. The top diameter of a stump less than 4.5 feet tall shall be considered the “DBH” of an illegally destroyed tree for the purpose of calculating recompense.
Lost tree means any tree that is destroyed, injured, or otherwise not protected according to the provisions of this ordinance.
Tree save area means the area surrounding a tree that is essential to that tree’s health and survival. At a minimum, the tree save area shall consist of a circle having a radius of one foot for each one inch diameter at breast height of the tree.
Sec. 158-105. Site plan required
- General requirements. The site plan shall include a tree survey, identifying the size, species, and location of all trees having a diameter at breast height (DBH) of six inches or greater. Such site plan shall contain topographic information at two-foot contour intervals and shall show all existing and proposed buildings and structures, driveways and parking grounds and all areas of required cut and fill. Such plan shall denote each tree to be saved, lost or destroyed, required tree protection fences for trees to be saved, and the proposed tree replacement plan. A construction limit line shall be delineated on each site plan submitted for a building permit. Within the construction limit line, the tree replacement requirements of this article shall be shown. Outside this limit line, no tree survey shall be required, and the applicant shall be required to leave undisturbed all areas of trees.
- Boundary trees. Boundary trees shall be included in the site plan. The on-site portion of the tree save area of a boundary tree shall be enclosed in a tree protection fence according to established arboricultural standards. In consultation with the owner or owner’s representative of a boundary tree, the city arborist may prescribe and the applicant shall institute additional protective measures to limit impact on the tree during construction, including but not limited regimes, root treatments, mulching, deadwood removal and protective pruning.
Where Are My Trees’ Roots?
One of the most frequently asked questions of community arborists is, “Will it hurt my tree if I cut the roots?” Indeed, tree roots are mostly ignored until they cause a problem by “popping up” in the yard, cracking a driveway, or tilting a sidewalk. Many people think removing a few of the tree’s encroaching roots will cause little long term harm and that large trees can easily recover from minor root loss, but that is seldom the case.
How much damage a tree’s root system can manage is a function of how much soil surface the roots occupy. The term “drip line,” which is often used to describe the limits of root length, is a poor indicator of roots’ true extent. Different species also have different types of root systems. However, most trees fall in line with the formulas below, which can be used to calculate the average length of a tree’s roots. But first a couple of definitions:
Total root zone area: Area within the soil profile where roots exist; typically the root zone of trees extends beyond the drip line.
Critical root zone: Soil area around a tree where the roots are located which provide stability and a significant uptake of moisture. In clay soils most of these roots lie in the top 12-14” of the soil. Damaging roots in this area can cause significant tree dieback or death.
Total tree root zone radius = diameter of tree measured at 4.5’ above the ground (dbh) X 1.5 feet. 12” dbh tree = 12” X 1.5’ or 18’ root zone radius around the tree.
Critical root zone radius = diameter of tree measured at 4.5’ above the ground (dbh) X 1.3 feet. 12” dbh tree = 12” X 1.3’ or 15.6’ critical root zone radius around the tree.
When calculating your tree root zones, remember that foundations, driveways, sidewalks, and walls can limit the effective areas that roots can occupy. Utility line replacement also frequently results in roots being cut or disturbed. Cutting or damaging more than 30% of the critical root zone area can cause dieback or death and may destabilize the tree. If you are unsure about the damage you may cause, contact a certified arborist for advice.
Editor’s Note: This article was originally published as a pdf by the Georgia Forestry Commission. To view the pdf including a graphic to help determine total and critical root zone radius, click here.