EXTENSION REPORT

The Six Worst Invasive Enemies of Alabama Forests

A gallery of invasive plants threaten Alabama forests today. Their use and appeal in the past have masked the dangers they present to Alabama forests today.

Many species remain highly popular ornamental gardening plants, though the Alabama Invasive Plant Council and experts such as our own Dr. Kenneth McNabb, an Extension Forester and Auburn University Professor of Forestry and Wildlife Sciences, are prevailing on homeowners to choose less destructive species. The six species identified as the worst threats to Alabama forestland include the following:

Kudzu

Native to China and brought to the United States for forage, soil erosion and shade on home landscapes, kudzu continues its unrelenting spread through forests, pastures and along right-of-ways in many Southern cities and towns.

Kudzu is extremely hard to control, thanks to its formidable array of defenses provided by Mother Nature.  Over time, kudzu roots expand and store carbohydrates underground.  This rich, underground store of food reserves provides the plant with unusual resilience, even after the visible parts of the plant have been killed. 

Tallowtrees

The planting of tallowtrees, native to eastern Asia and first introduced to South Carolina in the 1700s, was actively encouraged in the Gulf Coast region in the early part of the 20th century for a failed oilseed industry.

Tallowtrees are valued for their attractive red leaves in the fall.  They reproduce easily from seed and grow readily in the shade of other trees --- characteristics that have enabled it to thrive in the forest understory.  Even when they are cut down, they resprout not only from the stump but from root suckers.

The species poses an especially serious threat to bottomland hardwood ecosystems because the chemicals used to get rid of it also damage hardwood species.

Cogongrass

In terms of being a serious invasive species, cogongrass, transplanted accidentally from Asia, was relatively benign until roughly 15 years ago, when it first began to be noticed as a major threat to forestland ecosystems.

It has spread readily up and down Alabama highways via road maintenance machinery.  It throws out fine seeds, which, like dandelion seeds, are widely distributed by wind.  Equally bad, the grass, which originated in a fire-dominated ecosystem, is highly flammable and poses a fire hazard to forests.  It is drought hardy and can grow in low-fertility environments typically associated with pine forests.

Privet

Native to China and first introduced to the United States as an ornamental shrub in 1853, Chinese privet is now everywhere, including the forest understory.

Birds eat the privet’s fruit and spread the seed.  It already has altered the ecosystems in many pine and hardwood forests.  It appears to be particularly well adapted to hardwood forests, though less so on dry sites, such as pine forests.

Chinese privet, which can grow as high as 30 feet, is only one of several invasive privet species affecting Alabama’s fencerows, forested creek bottoms and upland forests. 

 Japanese Climbing Fern   

Native to Asia and Australia, the Japanese climbing fern was introduced into the United States in the 1930s.

It is spread readily by spores carried via water and wind. Contaminated pine straw is another major culprit behind the species’ spread.

While the fern dies back each winter, the previous year’s vine provides a trellis for additional new growth when warm weather returns.

Like many other invasive species, the fern displaces entire habitats and degrades the forestland ecosystem. It is also notorious for blocking land access.

Invasive Roses

Invasive roses are another prime example of species that were once widely promoted but that ultimately turned out to be a severe ecological menace. Native to Asia, the species was introduced into the United States as an ornamental and as a way to contain livestock and to enhance wildlife habitats.

Much like , the roses are found virtually everywhere --- pastures, forests edges, right-of-ways and wetland habitats. The roses form impenetrable entanglements that undermine land use and development.

            The information in this article was provided by James Langcuster, Extension Communication Specialist-Print Media, Auburn University and Dr. Kenneth McNabb.

Email address:swingard@aces.edu
Phone: 937-7176 or 943-5611, 928-0860, ext. 2222

Issued in furtherance of Cooperative Extension work in agriculture and home economics, Acts of May 8 and June 30, 1914, and other related acts, in cooperation with the U.S. Department of Agriculture. The Alabama Cooperative Extension System (Alabama A&M University and Auburn University) offers educational programs, materials, and equal opportunity employment to all people without regard to race, color, national origin, religion, sex, age, veteran status, or disability.