Despite Development, Durham’s Tree Canopy Continues to Grow 

As Durham experienced substantial growth in the past decade, previously forested areas, especially on the outskirts of the city, were cut down to make way for much-needed housing. The city has also lost parts of its tree canopy to weather events like Tropical Storm Chantal, or the thing that comes for all of us eventually: old age. 

To make up for the loss, Durham city staff and a network of volunteers and partner organizations have planted thousands of trees to maintain and increase the tree canopy, which provides numerous benefits to the environment and Durham residents.

The Durham City Council recently received an update on the status of the city’s tree canopy, which has held at over 50% since an assessment was last conducted in 2016, even as the city limits have expanded to incorporate new developments. 

The original study looked at about 110 square miles of land, with the canopy covering about 57.5 square miles (52%). The 2024 assessment includes the 121 square miles that make up the current city limits and the area included in the recently-adopted urban growth boundary (UGB), with canopy cover covering 64.7 square miles (54.7%) within city limits and 58.9% including the UGB area. The comprehensive plan, which guides Durham’s vision for future growth, calls for 55% coverage within city limits by 2040. The UGB establishes a limit for city utility extensions and annexations, meaning city limits could, in the future, extend to that line.

“Durham has done an amazing job of planting and preserving its trees,” said Sarah Lilley, urban forestry consultant with Eocene Environmental Group, an employee-owned sustainability consultancy that conducted the recent tree canopy assessment, during the council’s October 22 work session. Lilley said the city has been acknowledged with a Tree City USA designation for 42 years.

Tree canopy refers to the portion of private and public land covered by trees when seen from above. Outside of the city’s tree canopy, impervious surfaces like roads and rooftops make up 25% of land, with other natural surfaces like grass, soil, and water combining to make up the remaining land. The assessment group used a combination of in-person identification and computer imaging technology to capture the data.

Tree cover provides numerous health benefits to residents. The shade offers relief from the blistering summer heat. Trees are also exceptionally adept at removing pollutants and toxins from the air, and restraining stormwater run-off and erosion.

According to the city, the Urban Forestry division has planted over 15,000 trees in the past 10 years, with 85% of those trees being planted in eight historically underserved neighborhoods.

In 2023, the city made changes to its Unified Development Ordinance to limit the amount of land that can be developed at one time, and required larger developments to preserve a higher percentage of tree cover, in an effort to reduce the environmental impact of development and save more “mature” trees instead of replacing them with young saplings.

Still, the border of the city’s UGB ,where much of the city’s new development takes place, maintains notably higher levels of tree cover compared to the inner city. Downtown Durham, with its parking lots, parking decks, and large commercial and industrial sites, offers the weakest tree cover at 18%. Durham’s historically Black neighborhoods have also suffered from inequities in its tree canopy. Meanwhile, Southwest Durham has the densest tree canopy at 76%.

In December 2020, the city council took steps to remedy this issue by voting to allow more trees on city streets and on the right-of-way, with an emphasis on planting hundreds of trees in neighborhoods like Cleveland-Holloway, Edgemont, and Golden Belt in East Durham, where the tree canopy was a paltry 10% in 2016.

But the city is still limited in where it can plant new trees in the right-of-way. Power lines, underground water mains, street signs, and intersections where branches might disrupt a driver’s line of sight are all barriers. Urban areas also have limited soil and access to water, are more likely to become damaged from vehicles or chemical contamination, and require more frequent maintenance from city staff.

Based on these restrictions, the assessment estimates Durham could add roughly 2,665 acres, or about four square miles, of additional tree canopy if it could fully utilize the city’s right-of-way.

“We work with community partners, nonprofits, and universities to assist us in allocating more trees, to water the trees, to care for the trees, and to actually plant more trees,” said Kevin Lilley, assistant director of general services for the City of Durham.

The City of Durham is limited in the type of trees it can plant in the right-of-way near roads and other infrastructure because of the tree’s size and root composition, among other things, but partner organizations like Keep Durham Beautiful are able to plant a variety of trees, including fruit trees, in public parks and on private property in collaboration with landowners.

Durham ranks second only to Asheville in total tree cover for major metropolitan areas in the state, according to the latest tree canopy assessment. Much of the tree planting is initiated by city staff on public property, but residents are encouraged to participate, too.

“I think we are maintaining a very respectable tree canopy,” Kevin Lilley said. “Anytime you’re over 40%, it’s remarkable for a city the size of Durham. The fact that we have exceeded 50% and are going in the right direction considering the development that Durham has seen is phenomenal.”

Durham’s tree canopy will be increasingly more important, and at risk, as climate change creates more uncertainty each year. City staff said the ongoing drought has made keeping up with city-maintained trees challenging.

“So if you see a tree that’s not looking at the best, give it a break. It’s trying,” said Craig Reed, City of Durham Urban Forestry program manager.

Mayor Pro Tem Javiera Caballero echoed concerns about climate resilience, adding that the city council has encouraged more developers to include native trees in their projects because they are able to handle more extreme weather conditions compared to non-natives species. 

“Weather events are becoming more extreme,” Sarah Lilley said. “That’s hard for trees. It’s hard for all of us and there are further stressors on the urban forest such as pests that have been introduced. So maintaining your tree canopy is incredibly important.”

The city is working on a new urban forest management plan to take inventory of all the trees managed by the city within the right-of-way and funding models for ongoing tree maintenance, as well as a public survey for residents to share their thoughts on how to build Durham’s tree canopy.

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