No matter which way you spin it, invasive species are harmful to the environment. According to the United States Geological Survey, invasive species contribute to over $100 billion in damages to the U.S. economy each year. The NC Invasive Plant Council’s list of invasive plant species grows longer and longer every year, contributing to crop decimation, human disease transmission and more.
If you’re concerned about exotic critters invading campus, you’re not alone. Check out this Q&A with campus experts to learn the basics of invasive species, including the precautions students can take and how they can spread awareness regarding the impact of invasive plants and animals.
What are they?
The harm caused by invasive species can be measured across three sectors. Assistant professor and forest health extension specialist Dr. Kelly Oten incorporates those sectors into her research at NC State.
“An invasive species is a non-native species that causes harm either to our environment, to our economy or, in some cases, human health,” Oten said.
The term “invasive” can also be ambiguous; its interpretation overlaps with other species identifiers for introduced organisms, such as “naturalized” or “non native.”
According to Christopher Moorman, professor and associate head in the department of forestry and environmental resources, these definitions occupy a gray area.
“To be naturalized means that the introduced species is able to survive and reproduce on its own,” Moorman said. “To make it simple, I say that any naturalized species is also invasive. If a species can survive, reproduce and is outcompeting native species for space, then it has caused harm.”
So what makes a species “native”? Mark Weathington, director of the J.C. Raulston Arboretum, commented on the elusiveness of a definite definition.
“Native implies time and place,” Weathington said. “In North America, most of the definitions for ‘native’ center around what was here when the first white people came and recorded it. But, we need to decide: is that a valid definition anymore?”
Where do they come from?
So, how do invasive species enter into our communities? How should we monitor their spread?
“A real common way that [invasive plants] enter and have entered is through the ornamental plant trade,” Moorman said. “Another way is by accident. We’re a globalized economy and a globalized world with people and supplies moving all over the place.”
According to Oten, accidental introductions of forest insects can occur from trade involving wood as packaging material.
“If you think about it, there’s wood crates, pallets and support beams. If there’s a wood-boring insect inside, you might not even know,” Oten said. “A lot of those things are supposed to be treated, but sometimes things slip through the cracks and there’s human or equipment error.”
To reduce those accidental introductions, there are measures in place to treat wood and other plant products before they are shipped to different locations.
“Shipments that come into the country are inspected by [U.S.] Customs and Border Protection and there are agricultural agents at all of these international ports,” Oten said. “But, there’s a lot coming in so they can’t check everything. The numbers are actually pretty shocking; less than 2% of imports are actually inspected by these agents.”
However, beyond these protocols, there are precautions normal citizens can take.
“One of the best things that people can do is not move firewood,” Oten said. “We are accidentally moving these things hundreds of miles, sometimes within the span of a single day in our firewood.”
How should we approach them?
The evolving nature of the invasive species issue within North Carolina is not lost on Oten. Her research involves the implementation of management approaches for invasive species populations in the United States, specifically North Carolina.
“There are tactics that we use generally,” Oten said. “There are three major things that we consider: chemicals, biological control and host plant resistance.”
Currently, the only treatment for emerald ash borer infestations are insecticides, a type of chemical approach. The emerald ash borer, a metallic jewel beetle, attacks native ash trees.
“Our most recent [invasive] introduction was the emerald ash borer,” Oten said. “It has also spread very quickly. It can be found in over 60 counties in the state, and we only just detected it in 2013. It has been detected in Raleigh, and there are infested trees on campus.”
Research on biological control and host plant resistance is being done for the emerald ash borer. Oten expressed hope that chemical management for emerald ash borer will serve as a short-term solution as researchers look for long-term options.
If left untreated, Oten said, invasive species can “forever change the landscape of our state.” For instance, chestnut blight, a historic fungal disease, ravished the once dominant American chestnut tree for many years.
“Chestnut blight has killed the majority of our large, mature chestnut trees,” Oten said. “Although you can still find American chestnut seedlings in the forest, the species is considered functionally extinct.”
What does the research say?
Moorman elaborated on the newness of the research on how invasive species might impact native species conservation.
“This is an emerging area of research,” Moorman said. “It’s hard to paint with a broad brush, but typically, when we have non-native plant invasions, they outcompete native plants and they reduce the diversity of native plant species.”
At the J.C. Raulston Arboretum, Weathington encourages the use of the Arboretum’s landscape plant collection for research purposes. In the past, the Arboretum’s collection has been used in support of native ecosystem rehabilitation projects.
“If you are rehabbing a native ecosystem, then you would certainly want to plant native plants, preferably with genetic material from close-by populations,” Weathington said. “I believe in cultivated landscapes — we should plant the right plant in the right place.”
Educating yourself and others about invasive species
The proliferation of invasive species across the United States will undoubtedly continue into the future. An unfortunate “new norm,” as Moorman described it. However, there are options for students who want to assist with invasive species prevention.
“Advocate for the value of native plants and plant communities that are dominated by native plants,” Moorman said. “Probably the best way to do that is through education.”