Invasive species push out natives and take over

It’s a scenario straight out of a science fiction story. An alien invasion begins to take over, stealing food and other resources and supplanting native life.

But it’s real, just instead of an extraterrestrial species, imagine a spotted lantern fly, or maybe bush honeysuckle.

While they may not sound nearly as shocking or spooky, these aliens are invading our environment and taking over, pushing out native species.

We’re talking about invasive species. They take all shapes and forms: plants, animals, insects, large and small, beautiful and menacing. One thing they all have in common is that they can do serious damage.

Take the emerald ash borer, for example. This tiny iridescent green beetle has nearly wiped out ash trees across swaths of the country, including here in Indianapolis.

We know invasive species cause problems, for this week’s Scrub Hub, we are looking at how invasive species get here.

To find the answers, we spoke with experts from the Indiana Native Plant Society as well as the State of Indiana Cooperative Invasives Management.

Short answer: Accidentally and intentionally introduced

Most simply, invasive species are those that are growing outside their natural range, according to Dawn Slack, the project coordinator for the Indiana Invasives Initiative. They can cause harm to not only the environment, but also human health and the economy.

Invasive species can be introduced in a variety of ways, sometimes accidently and sometimes intentionally. Either way, it all comes back to horticulture, or the practice of garden cultivation and management.

PURDUE UNIVERSITY DEPARTMENT OF ENTOMOLOGY/JOHN OBERMEYER

Many invasive plants are actually introduced into areas outside their natural range by humans, according to Slack, for various reasons including landscape uses, food production, research and more. Many of these introductions happened decades ago before conservationists started to understand the importance of native plants, added Tom Hohman, who served with the Central Chapter of the Indiana Native Plant Society.

Many invasive insects often come over in packing materials or hitch a ride with infected plants. That means many invasives are introduced and not discovered until they become established. By then, it’s too late, Hohman said.

That’s the case with Asian jumping worms, for example, that are being spread across Indiana in the soil of donated plants.

Long answer: Hard to stop the spread

Once an invasive species is introduced, it can be hard to get ahead of to stop the spread. That spread can happen in a variety of ways.

Humans can share plants and seeds without knowing they are a problematic species. Contaminated equipment clothing or shoes can move seeds to new places.

The seeds and fruit can be blown far or carried in rivers and streams. Or wildlife may eat the seeds and fruit and then drop them out elsewhere.

Bradford or Callery pear trees are a perfect example. Their beautiful spring blooms made them a popular tree for landscaping and public rights of way. Now you may see them on road-sides everywhere or near highway exit and entrance ramps.

Many of those weren’t planted, they popped up on their own.

These trees are so pervasive that Carmel is now on a long-term mission to remove the controversial invasive species that can choke out native ecosystems.

That’s what happens, these invasive species take over because there are no native diseases, insects or predators to help keep them in check. In a native ecosystem, everything fits in somewhere in the chain. Invasives, however, introduce a kink into the system.

Many invasive species also have longer growing or active seasons, which is becoming more of an advantage for them as climate change brings warmer temperatures.

This advantage also can be a disadvantage, according to Slack. Because invasives will grow while natives are dormant, there is an opportunity to more easily identify and manage invasive species.

Slack said they are making some strides in treating infestations of invasive species, but added her organization has a “backlog of infestations to deal with and we continue to introduce plants into areas outside their native range.”

The best thing is to stop invasives from ever being introduced, Slack said.

That means, as simple as it may sound, planting native species in the landscape and using resources such as the Indiana Native Plant Society to make the right choices.

“Our beautiful spring and summer gardens and natural areas will be able to flourish with the invasives out of the way,” Slack said.