Specialty Tree Care
Learn more about the services we provide
City of Atlanta Tree Prescriptions
The City of Atlanta Tree Ordinance protects any tree over 6 inches in diameter. It is often the case during a building project, that trees over 6 inches in diameter are negatively impacted by construction activities but not killed. In very specific circumstances, the City allows impact to occur if the homeowner hires a private arboriculture firm like Arbormedics to care for the trees during the building project.
The first step in this process is to use the City of Atlanta’s formula to calculate the building project’s impact to the tree. The City formula stipulates that the tree’s root zone (Critical Root Zone, CRZ) is equal to a circle with radius (in feet) equivalent to the trunk diameter measured (in inches) at 4.5 feet above ground level. For instance, the critical root zone of a 24 inch Oak would be a circle surrounding the tree with a radius of 24 feet. The impact to the CRZ is calculated as a percentage of the impacted area divided by the total area of the circle.
If the impact percentage is less than 0-19%, the City does not automatically require you to hire an arborist to help the tree.
If the impact percentage is 20-32%, the City often allows you to proceed as long as you hire a firm like Arbormedics to perform a “Tree Prescription” or “Silvicultural Prescription” (different names for the same procedure).
If the impact percentage is 33% or more, the tree is declared “lost” and you will be required to plant trees to maintain the overall tree canopy in Atlanta, or you will be required to pay recompense which will be used to plant trees on public land.
A Tree Prescription is two things. First, it is a set of recommendations for the tree during the construction process. The most common recommendations are treatments that will repair the damaged root system and encourage new root growth. Second, the tree prescription consists of the actual implementation of these recommendations and treatments. A Tree Prescription is not just paper! The tree needs to receive its medicine as part of the process!
The City of Atlanta requires us to provide them with very specific paperwork documenting our tree prescription on your property. One required component is a “paid in full receipt” showing that the property owner has paid us for our services and that the services are either complete or in process. People often find this part of the process disconcerting. The reason the City requires the “paid in full receipt” is that over the years builders became notorious for signing contracts with arborists to do the required work, and then calling the arborist as they left City Hall with their building permit to cancel the actual work before it ever occurred!
At Arbormedics, we offer full turnkey Tree Prescription services to guide you through the process from start to finish. This includes the initial site visit, prescriptive recommendations and tree care treatments.
PiCUS Sonic Tomograph
ArborMedics Offers Innovative Sonic Scanning of Tree Trunks
Arbormedics continues to be the only company in the Southeast to offer sonic scanning of tree trunks as a regular diagnostic service. This advanced diagnostic service allows us to literally see inside tree trunks using sound waves in a process similar to an ultrasound or MRI. The resulting scan image allows us to understand the structure and health of living trees in a new and dynamic way. The image also provides an accurate baseline for us to track the health and safety of trees over time. Sonic scanning uses the fact that the velocity of sound in wood depends on the modulus of elasticity and the density of the measured wood. Cavities, white rots, brown rots, and other fungal decay reduce elasticity and density in wood. These wood characteristics vary between trees species and between individual trees. The Picus Sonic Tomograph uses relative sound velocities so that the system calibrates itself automatically at each measured cross-section. The sonic scan provides information about the possible presence of decay and cavities within a tree. The system is not foolproof, however, and images should not be interpreted as fact. A tree should never be preserved, or removed, based solely on a sonic scan. A sonic scan is a test of one cross-section of the tree. The location of testing was chosen by your arborist based on visual signs of defect and limiting factors of the hardware. Please remember that the cross-section of the scan may not represent the weakest location in the tree’s overall structure. Fungal pathogens often invade the trunk via the buttress roots. It is safe to assume that if the scan identifies a potential fungal pathogen, it may have been active longer and more aggressively in the root system below the point of the scan.
Don't Drill Holes in Your Trees!
Unfortunately, the majority of arborists in the Southeast continue to use hand drills or "Resistograph" machines in an attempt to locate decay in tree trunks. These machines were developed to find rot in telephone poles---not living trees! When arborists drill into a living tree trunk, they breach the tree's natural defensive barriers and allow decay fungi to move from sick to healthy areas of the tree trunk.
Besides injuring the very tree it is trying to evaluate, a "resistograph" machine produces far less data than our sonic scans. A typical arborist would drill a tree 6-10 times in an tree inspection and have to guess the rest of the story. A typical sonic scan creates the equivalent amount of data as 189 drillings and provides that information in an accurate, digital image.
ArborMedics offers sonic scans at a lower rate than our competitors' invasive drilling procedures. It is our philosophy that sonic scanning should be affordable so that people can understand important issues about their tree's health and safety.