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Forest Succession in the Urban Forest

Dr. Leslie Edwards is the lead author of the book, The Natural Communities of Georgia. Dr. Edwards received her PhD at the University of Georgia and recently retired from the faculty of the Georgia State University Geosciences Department, where she taught urban ecology and natural ecosystems. She has spoken and taught extensively about native plants and ecosystems, and has served on the boards of many conservation organizations. We fondly know Dr. Edwards as Leslie and are proud to have her as a Trees Atlanta Docent.

Register for Leslie’s upcoming Tree Tour:

Tree Tour: Atlanta Memorial Park
Sat Mar 25 | 10am-11:30am | Atlanta Memorial Park

 

Written by Leslie Edwards, Trees Atlanta Certified Volunteer Docent

Atlanta is the “City in the Forest,” with the highest percent tree canopy cover of any U.S. urban area. Interestingly, though, these forests are not the original ones that existed centuries ago, when the native people maintained a landscape of primary forest and field. Early European colonists cleared those forests for farming, mills, and population centers. Now, forests are returning through the important process of forest succession, wherein plant communities progress in stages from cleared land to forest.  

There are four main stages of forest succession. Each stage brings diversity and beauty to the landscape, with different plant and wildlife communities. 

There are four main stages of forest succession (although ecologists often apply different labels). Each stage brings diversity and beauty to the landscape, with different plant and wildlife communities. Environmental conditions and animal-ecosystem interactions can encourage succession or keep an ecosystem at a specific stage. Some of these conditions include water availability, the presence of fire (the southeast historically had frequent small fires due to lightning strikes), and soil health/depth.

The stages, including where they can be seen in Trees Atlanta restoration sites and in the Atlanta BeltLine Arboretum, are: 

 

Stage 1 – Grassland/Meadow

Non-woody plants, such as grasses and wildflowers, are the first to colonize cleared land. These plants are “pioneers.” They grow quickly, thrive in tough, sunny conditions, and have light seeds that arrive quickly on a site. Meadows are very diverse. Birds, pollinators, and other wildlife thrive among the grasses and wildflowers in this habitat. 

Look for meadows all along the Atlanta BeltLine Arboretum.

 

Stage 2 – Shrubby Grassland/Brush

Woody pioneer plants, such as loblolly pines, sweetgums, shrubs and brambles, soon rise above the grasses and wildflowers. The addition of shrubs and young trees provides an even greater diversity of insects, berries, seeds, flowers, and places to nest and shelter, so birds and pollinators thrive. 

Look for shrubby areas mixed along with the meadows on the Atlanta BeltLine Arboretum and in patches of forest, such as Lake Charlotte Nature Preserve.

 

Stage 3 – Young Pine Woodland

Pines grow quickly and rise above the other trees. Over time the shrubby grassland is shaded out, and forest plants move in. Oaks and other hardwoods whose seedlings can grow in the shade (known as “shade tolerant” plants) grow slowly under the pioneer trees. Birds, chipmunks, and other wildlife adapted to foraging and sheltering among trees become common.  

Look for these woodlands at the edges of shrubby grasslands and among forest patches around Entrenchment Creek, Westside Park, Woodall Creek, Legacy Park, and South Bend Park.

 

Stage 4 – Mature Forest

Oaks and other hardwoods overcome the shorter-lived pines, creating a hardwood forest. Over time, trees fall and cause gaps in the forest, and shade tolerant saplings spring into the tree canopy. Dogwoods and other small trees form a mid-story. Mature forests have distinctive traits, including a variety of tree ages and sizes, fallen trees, thick leaf litter, twining vines, and shade tolerant shrubs and ground cover. Together, these elements form a complex ecosystem with a huge diversity of insects, birds, and mammals. They also bring health and relaxation benefits to people. These are what make our “Forest in the City” so special.

Look for mature forests in Cascade Springs Nature Preserve, Lake Charlotte, and Frazer Forest.

Images above L-R: Early meadow grasses in the Atlanta BeltLine Arboretum Eastside Trail, 2015 photo credit Christina Gibson; area known as “Succession Hill” was planted with early succession trees, Eastside Trail near Freedom Parkway, 2019 photo credit John Becker; Westside Trail Bog Garden foreground with Long-leaf pine collection in background, 2021 photo credit Kelly Ridenhour; and the mature forested areas near Mozley Park on the Westside Trail, 2019.

 

Posted on: February 3, 2023