Nonnative, invasive plant species pose a threat to forest resources throughout the South.
Increasingly, nonnative plants infiltrate landscapes, eroding and replacing native plant communities. This can have irreversible and degrading effects on critical, human-sustaining ecosystems.
Tallowtree (Triadica sebifera) is one of the most pervasive exotic tree species in the South and is known to replace entire stands of forests. Sometimes called popcorntree due to the resemblance of its seeds to popcorn, tallowtree was first introduced to coastal South Carolina and Georgia in the late 1700s. Then, in the early 1900s, the U.S. Department of Agriculture (USDA) promoted planting of tallowtree along the Gulf Coastal Plain in Texas as a source of oil for industrial applications. The USDA has long since abandoned this program, but the tree continues to be planted as an ornamental and by beekeepers.
Following its introduction in the late 1700s, tallowtree rapidly took over the Gulf Coast that stretches from Florida to Texas, covering over 500,000 acres in Texas and Louisiana alone. U.S. Forest Service Southern Research Station (SRS) Forest and Inventory Analysis (FIA) data suggest that tallowtree has increased 174 percent in east Texas and more than 500 percent in Louisiana since the early 1990s; this aggressive invasive is now the fifth most common tree species in east Texas and Louisiana, and the most widespread and abundant nonnative tree in the Mississippi Alluvial Valley, according to a newly published report.
Tallowtree is a hardy plant. It can grow in almost every habitat type, from streambanks and wetlands to grassland prairies and other upland sites. It also thrives in various soil types, including both freshwater and saline soils. Tallowtree is shade-tolerant and can withstand periodic floods. In addition to these ecological characteristics, warming temperature trends and an increase in major destructive weather events facilitate and even accelerate the plant’s rate of invasion.
“Tallowtree has a tremendous capacity to change whole ecosystems,” says Sonja Oswalt, forester with the SRS FIA unit. This species can be particularly problematic in that it can move into native prairies and convert them to monoculture tallowtree forests.
In 2010, SRS published A Field Guide for the Identification of Invasive Plants in Southern Forests. Jim Miller, lead author of the guide, is one of the foremost authorities on invasive plants in the South; co-authors are SRS research technician Erwin Chambliss and Auburn University research fellow and extension specialist Nancy Lowenstein. The book provides information on accurate identification of the 56 nonnative plants and groups that are currently invading the forests of the 13 Southern States. It lists other nonnative plants of growing concern.
The information included in the guide is now available as a free application for iPhones, iPods, and iPads called Invasive Plants in Southern Forests.
Recommendations for prevention and control of invasive species are provided in a companion booklet, A Management Guide for Invasive Plants of Southern Forests, which Miller co-authored with Steven Manning, president of Invasive Plant Control, Inc., and Stephen Enloe, Auburn University weed management extension specialist.