Restoring the Olmstead Oaks

Hillside erosion
- Photo Credit: Francesca Gross
Acorn in leaf litter
- Photo Credit: Francesca Gross
Young oak
- Photo Credit: Francesca Gross
Flagged oak seedling
- Photo Credit: Francesca Gross
Oak canopy
- Photo Credit: Francesca Gross
Stressed park tree
- Photo Credit: Birmingham Botanical Garden
Volunteers planting oaks
- Photo Credit: Birmingham Botanical Garden

When the Olmstead Brothers designed Green Springs Park (now George Ward Park) in the 1920s, they left the oak and hickory woods in place and opened up the natural meadows for passive recreation. A number of these same trees still stand in the park and represent a direct link to the original forest. However, since the park’s opening in 1925, the trees have produced virtually no offspring, and the number of mature trees in the park is diminishing each year due to lightening, high winds, and old age.

So why aren’t there any new trees? As the years passed, more recreational uses were added to the park, including large softball diamonds, tennis courts, and disc golf. The oaks and hickories continued to grow tall and strong, but the common practice of mowing and removing understory shrubs and trees eventually left erodible soils unprotected against the rain and wind. Henry Hughes, director of education at the Birmingham Botanical Gardens (BBG), noticed that new oaks were not growing up under the old oak canopy as they would in a natural forest. He gathered a few acorns and potted them up at the BBG greenhouses. Then he potted a few more. The BBG relationship with the Garden Club of America  (GCA) provided the motivation for reforestation with these precious acorns. In anticipation of the GCA’s 100th year anniversary, in 2013, they asked the members of their 200 clubs to head a Centennial Tree Program in their communities. Generating seedlings from the park’s ancient oaks was a perfect fit for their theme of “preserving the past, growing the future.”

Starting in October of 2009, the first 100 seedlings were planted at George Ward Park. After five years, Hughes and the BBG had generated more than 5,000 seedlings from the oaks and other native trees in the park. With the help of two local garden clubs, Little Garden Club of Birmingham and Red Mountain Garden Club, and other volunteers, the trees planted in the park are now primed to take over as the stately old oaks meet the end of their reign.

Props go to Little Garden Club, Red Mountain Garden Club, Friends of George Ward Park, Glen Iris Neighborhood Association, the Birmingham Disc Golf Association, the Jefferson County Master Gardeners, the Japan American Gardens Society, and the staff of the Friends of the Birmingham Botanical Gardens for their help in this reforestation effort. Henry Hughes’ work was recognized in 2014 with a Zone VIII Horticulture Commendation from the Garden Club of America.

The Centennial Tree program is the centerpiece of the BBG conservation program –  Using long-lived native trees, grown from seed of local provenance, BBG’s Centennial Tree program facilitates urban forest regeneration in local cultural landscapes (such as parks) and natural ecosystems (such as urban waterways), where native trees have been damaged or lost due to natural senescence, storms and disease; and/or where the soil has been damaged by compaction or erosion. The central ideas are 1) local seed sources of appropriate native trees are best for long-term rehabilitation of urban forest sites and 2) concerned individuals and groups can have short- and long-term positive impacts in these efforts. 

To ensure plant survival and encourage volunteer native plants in the understory, Birmingham Public Works and the Parks and Recreation Board employed new maintenance procedures. New practices include leaving the leaf litter under the tree canopy to allow more water retention in the root area, mulching, and not removing “weeds” from under the trees. Fallen branches hold fall leaves in place and will begin to restore the topsoil. Acorns then will have a chance of germinating on their own without the need for collecting seeds and seedlings.

Hughes followed the planting success with a study of the tree seedling survival. With help from BSC student Caroline Rowan, he evaluated a three-acre reforested area after the five-year period of planned forest management. They examined mature trees, planted trees, volunteer trees, and herbaceous vegetation, and Rowan found that about one-third of the planted trees survived. Many volunteer trees and herbaceous plants colonized the restoration area for the first time in many years. This project serves as a reforestation model for other urban parks.

Hughes and Rowan found that the mature canopy has 12 tree species: southern red oak (Quercus falcata), post oak (Q. stellate), black oak (Q. velutina), blackjack oak (Q. marilandica), water oak (Q. nigra), black cherry (Prunus serotina), mockernut hickory (Carya tomentosa), red hickory (C.ovalis), loblolly pine (Pinus taeda), Virginia pine (P. virginiana), flowering dogwood (Cornus florida), and sweetgum (Liquidambar styraciflua). Black cherry was most represented, followed by sweetgum and post oak.

They also found 13 tree species grown by the BBG and planted by volunteers. These included the top three oaks (southern red, post, black jack, and black oak), two hickories (red and mockernut hickory), persimmon (Diospyros spp.), blackgum (Nyssa sylvatica), and four oaks not found in the three-acre area: white oak (Q. alba), scarlet oak (Q. coccinea), burr oak (Q. macrocarpa), chestnut oak (Q. prinus), and northern red oak (Q. rubra). More than half of the volunteer trees were easily propagated sweetgum, cherry laurel (Prunus caroliniana), and sugarberry (Celtis laevigata).

This is a great example of urban forest management combining the reintroduction of native plant stock and plant-friendly park management practices. Through volunteer efforts and the love of trees, Birmingham is re-growing its native forest – in the middle of the city. Relax under a spreading oak today and thank the Olmstead Brothers and Henry Hughes.

Francesca Gross