Alachua is one of the top counties in the state for numbers of invasive species, and Brandon explains what that means.
On any given sunny summer afternoon, you can spot them. They scurry from bush to bush, shrub to shrub, under shoes and bike tires. They are young, brown lizards, and they seem to be multiplying. Most Floridians can’t remember a time when they weren’t here. But on an evolutionary scale, they are very recent residents of Alachua County.
These small reptiles are brown anoles (that’s uh-noles), scientifically known as Anolis sagrei, part of a group of tropical lizards that includes about 400 other species. There is another resident anole here, too: the bright green Carolina anole, Anolis carolinensis. But you don’t see those too often anymore. The brown anole, thought to have arrived here as a plant trade stowaway and pet trade escapee from Cuba and the Bahamas, is now firmly entrenched in Alachua County and beyond. And its population is outgrowing its green counterpart, the sole anole native to the United States.
To Deah Lieurance, Ph.D., coordinator of the UF/IFAS Assessment of Non-native Plants in Florida’s Natural Areas, this is nothing new — especially in Florida. To her and other scientists, pesky organisms such as the brown anole are known as invasive species, and they are a serious problem.
An invasive species, Lieurance said, is any plant, pathogen, animal or insect that is not native to the area and causes ecological, environmental or economic harm. With 368 listed, Alachua County ranks seventh out of 67 Florida counties for the most reported invasive species, according to University of Georgia’s Mid-Atlantic Early Detection Network annual report. Local natural areas such as Payne’s Prairie Preserve State Park and San Felasco Hammock Preserve State Park are susceptible to such invaders and are at the root of an ongoing management battle. Water hyacinth (Eichhornia crassipes), one of the worst aquatic weeds in the world, and coral ardisia (Ardisia crenata) are both prevalent here, choking out natural ecosystems and inflicting hefty environmental costs.
“I was shocked to see [water hyacinth] that dense this far north,” Lieurance said.
But those aren’t the only species worrying scientists.
“Air potato is pretty widespread,” she said. “Japanese climbing fern, Mexican petunia, Chinese tallow tree… those are all invasive in Alachua County.”
Local natural areas such as Payne’s Prairie Preserve State Park and San Felasco Hammock Preserve State Park are susceptible to such invaders and are at the root of an ongoing management battle.
At their best, invasive species are simply nuisances, creating a droll palate of a single species called a monoculture. At their worst, prolonged stays by invaders can lead to the expulsion or extinction of the area’s native species.
Invasive species can negatively influence the way nutrients like nitrogen cycle through the system, hinder adaptations to natural fire regimes and even contribute to erosion, Lieurance said. All of these processes open the door to other invaders, further damaging the ecosystem.
Many species that become established invasives begin life as a pretty, ornamental plant, cultivated for long-lasting vibrant blooms or shade tolerance. In fact, according to Lieurance, about 82 percent of woody plants, shrubs and trees have some connection to horticulture, landscaping or agriculture.
“A lot of these plants were introduced with the best intentions,” she said. “And now we know the traits that make them invasive.”
Illustrating this is the case of Lantana camara, a flowering shrub that has become a problem in Gainesville and around the world. On UF’s campus, Lantana camara is a common sight, used for a welcome splash of color in the built landscape. However, its beauty is supplanted by its deadliness. The toxic plant has a high capacity for seed dispersal. This allows it to outcompete the now-endangered and closely related native Lantana depressa in the wild.
In Lieurance’s office, researchers work to assess plants, including ornamentals such as Lantana camara, for their invasive potential. This way, researchers ensure cultivars don’t bring in potentially problematic species and that plants used ornamentally are bred to be sterile or less troublesome.
“Essentially we compile all that data and make a recommendation on whether a plant should be used or not in Florida,” Lieurance said. “If there’s ample evidence that something is invasive, if it’s encroaching in natural areas and causing ecological harm, we would not want to recommend that as a university.”
According to Lieurance, about 82 percent of woody plants, shrubs and trees have some connection to horticulture, landscaping or agriculture.
In their home ranges, species that may become invasive elsewhere are often held in check by factors that limit their dispersal or competitiveness. For instance, those air potatoes mentioned earlier (Dioscorea bulbifera) are held in check in their native range by predation from the hungry air potato leaf beetle (Lilioceris cheni). When a species is transported across borders and becomes established in a strange, exotic new land (such as Gainesville), they no longer have to worry about getting eaten, and they are free to colonize and spread all over the place in a phenomenon known as enemy release. In Alachua County and across much of Florida, City of Gainesville habitat naturalist Grace Howell said transplantation of air potato leaf beetles in 2013 took a big bite out of air potato population. This is a clear example of a biological control tactic “reuniting” invader and natural enemy, reducing the need for mechanical or chemical controls, which are costly to wallets and the environment.
In fact, these small red beetles are so effective that the Great Air Potato Round-Up, a 16-year-old local tradition, has had to rebrand, Howell said. The Great Invader Raider Rally, as it is now known, is entering its second year under the new name this January and now focuses on other invaders such as coral ardisia and camphor tree. It attracts more than 1,000 volunteers each year.
Volunteer manual labor isn’t the only way to fight invaders: One can simply refuse to buy them at the nursery. Resources, such as those at UF/IFAS, allow buyers to select alternative native species that have benefits such as needing less watering.
To prevent invasive species from gaining a foothold on your property, or to learn more about invasions or the Raider Rally, contact your local Florida Fish and Wildlife Conservation Commission, city parks department or IFAS extension office.
Globally, the number of established non-native species is steadily increasing as the climate changes and the world becomes increasingly connected. Nowhere is that more evident than in Florida, where we have our fair share of invasives. However, thanks to the efforts of scientists and management professionals studying and educating the next generation, we are not going down without a fight.