A yearlong study to document Macon and Bibb County’s tree canopy is in its early stages, measuring the amount of various types of land cover.
The measurements will be part of a larger project, funded by a Knight Foundation grant, that may lead to a revision of the city’s tree ordinance.
“Tree canopy is essential and irreplaceable,” said Connie Head, an urban forestry consultant with Technical Forestry Service. “It’s part of a city’s infrastructure. It’s as important as our road networks, fire, police. ... It allows us to breathe and increases the value of an area.”
In 2008, Macon’s tree canopy was 37 percent, down more than 2 percent from measurements in 1991, according to numbers from the University of Georgia Natural Resources Spatial Analysis Laboratory.
Ecologically, 50 percent would be ideal, Head said, but 40 percent should be an absolute minimum for a city Macon’s size.
“It’s up to each community to decide for itself (what the right percentage is),” Head said, which is why she has been commissioned by the city of Macon and the Macon Tree Commission.
In 2001, Bibb County had 49 percent tree canopy coverage, Head said, but due to the development of the area since then, that percentage is expected to be lower this time around. Through the study, she is calculating numbers for Macon and also for all of Bibb County.
“This is coming at a good time because of the potential for consolidation,” Head said. “This is planned to be a sister ordinance, so it’ll be the same for both (Macon and Bibb County).”
Macon’s current tree ordinance addresses only public property and rights of way, Head said.
“This is unique among cities in Georgia of the size of Macon,” she said. “In fact, all cities greater than 30,000 population, except for Macon, regulate tree canopy cover on new developments.”
The project will analyze 85 aerial-view maps of the city and county, representing 2,560 acres each. Most of the maps include nearly 5,000 dots which must be color-coded based on the cover type at that spot on the map. Those conducting the study are measuring five land cover types -- tree canopy, other vegetation, hard or impervious surfaces, bare soil or gravel and water.
It’s a tedious process. Not even at the halfway point of analyzing the maps Thursday, more than 100 people had spent a total of 300-plus hours of labor. By the end of the process, more than 300,000 dots will have been studied and colored. Mercer University and Wesleyan College students helped with the map analysis, some for class credit and others as volunteers.
“It’s surprising that even outside of the urban areas, and in the new developments, how few trees there were,” said Mercer senior biology major Catie Duskin, who is originally from Dawson, a town near Albany.
Smaller communities tend to have higher tree canopy percentages, Head said, noting that Rome has a 49 percent measurement, and Oxford has about a 60 percent tree canopy. Smyrna, however, had just 39 percent, she said, which was very low.
“As tree canopy decreases, it increases things like storm water runoff and pollution,” Head said. “It also decreases the economic and psycho-social benefits of having more trees.”
Head said that ideally this will become a regular survey for the area. That way, the data from this year can be used as a baseline. In order to track trends, the measurements should be taken every five years because of the changes of landscapes from development.
This idea would be especially important for the county measurements, said Heather Bowman Cutway, a biology professor at Mercer.
“Within the city limits, you don’t see as much change, but the county is where you see such rapid changes occurring,” she said. As an urban ecologist, she said laying it out on a map allows even those with untrained eyes to realize what’s really there when there is an area full of red dots, which represent hard and impervious surfaces.
“It’s extremely visual when you can see the dots and see that there are no trees there,” she said.
After the assessment is complete, Head will measure surface temperatures, conduct a strategic planning session and develop recommendations for revisions to the ordinance.
“An ordinance of this type has been attempted in the past,” Head said. “It just has not been adopted.”
She said the plans are to have a proposed ordinance drafted by the end of the year. “(Macon) is a beautiful city with lots of gorgeous architecture,” she said. “You deserve more trees.”