Floodplain Restoration at the State Botanical Garden of Georgia
The Middle Oconee River forms the southern border of the State Botanical Garden and the Mimsie Lanier Center for Native Plant Studies lies within its floodplain. In years when the river overflows its banks, the floodplain is temporarily submerged for days or weeks. The floodplain forest is a diverse plant community that is adapted to the soils and hydrology of this dynamic riparian habitat.
Unfortunately, our floodplain forest, and thousands of acres like it along the Middle Oconee River, have been taken over by a ruthless invader — Chinese Privet (Ligustrum sinense). Chinese Privet produces small fruits that are dispersed by birds and probably by floodwaters as well. Once established in a forest understory, Chinese Privet can spread rapidly, forming thickets that exclude other species and casting a dense shade that discourages the growth of native plants.
Our effort to remove Chinese Privet from the State Botanical Garden floodplain involves three steps: (1) removing the aboveground stems of the Chinese Privet with a mulching tractor that runs on tracks, which reduces impact to floodplain soil; (2) spraying the privet with herbicide as it re-sprouts; and (3) restoring diversity to the forest understory by planting native species of shrubs, grasses, sedges and wildflowers that we have propagated from locally collected seed. Scientists at the Mimsie Lanier Center will evaluate the success of these out-plantings so that we can recommend species for other floodplain restoration sites in the Piedmont. These efforts are currently supported in large part by a grant from the U.S. Institute of Museum and Library Services.
Piedmont Prairie Restoration and Research at the State Botanical Garden of Georgia
For many decades, ecologists believed that before Europeans settled Georgia in the mid-1700s, our Piedmont uplands were blanketed with an unbroken forest of hardwood trees such as oaks and hickories, with the occasional pine tree. Now we know that the landscape was a lot more diverse than that, studded here and there with grassy, sunny openings we call “Pocket Prairies.” What caused the openings? Probably a variety of factors such as the type of bedrock and soil, lightning-set fires, grazing by large herbivores such as elk or possibly bison, and land management practices of the Native Americans who lived here for thousands of years before European colonization. Pocket Prairies supported a large number of plants and animals, and added a lot to both landscape and species diversity. After 250 years of agriculture and development, prairies have nearly disappeared from the Piedmont. The plants and animals that live there are now relegated to artificial clearings such as utility and roadside rights-of-way. As a result, several prairie-related plants are endangered or threatened: smooth coneflower, Georgia aster, dwarf sumac, curly-heads and several others.
Thanks in part to funding from the U.S. Institute of Museum and Library Services, the State Botanical Garden conducts research on the best methods for creating and restoring prairie habitats. We are also developing propagation techniques for a variety of plants that thrived in Piedmont Prairies, especially grasses, legumes and many species in the sunflower family. Once we have a good idea of their ecological needs, we will introduce these plants to suitable clearings here at the Garden, especially our powerline right-of-way, and elsewhere in the state where prairie plants can flourish. These outplantings will provide seed sources – and inspiration – for future Piedmont prairie restoration projects in Georgia.
River Cane Restoration at the State Botanical Garden of Georgia
River Cane (Arundinaria gigantea) is a North American native bamboo species that has captured the attention of restoration ecologists in the Southeast. It is a high priority species in the Garden’s effort to restore native plant diversity to our disturbed floodplain habitat along the Middle Oconee River. Canebrakes (dense thickets of River Cane) were once an important habitat along floodplains in the southeastern U.S. Pre-Columbian Native Americans utilized the plant extensively in tool-making, construction, crafts and medicine. Today, indigenous communities in the Southeast value canebrake as an important cultural landscape and material resource for traditional art forms. Canebrakes also provide important wildlife habitat for a variety of neotropical birds and insects, including the extremely rare Bachman’s warbler, which depends on canebrakes for nesting sites. Large canebrakes are much less common today, but small patches of River Cane still occur naturally in the understory of the floodplain forests of the State Botanical Garden of Georgia (SBG).
A UGA College of Environment and Design graduate student, Thomas Peters, studied the ecology and propagation of River Cane at SBG for his master’s thesis. He conducted a detailed assessment of 14 natural populations of River Cane on the SBG grounds and provided management recommendations to encourage their reproduction. In addition to encouraging the spread of our existing patches of River Cane, we are purchasing plants (propagated from local ecotypes) and establishing them in additional sites as part of our floodplain restoration project. This effort is funded by a grant from the federal Institute of Museum and Library Services as well as the O’Grady Bird Habitat Restoration Project established by the Oconee Rivers Audubon Society.