Guest Post: Repelling Invasive Species: Lessons from Around the World

Invasive species are bad news for native flora, fauna and even for humans. Animals, plants, and even microbes that aren’t native to an area can take over an entire ecosystem shortly after being introduced in this area and cause native species to disappear.

The only way to protect an ecosystem from the negative impact of an invasive species is to repel, or at least control, the invaders and support a diverse and healthy ecosystem where native species can thrive.

How Are Invasive Species Repelled?

Each ecosystem is unique. When an invasive species takes over an area, it is important to develop a solution that targets the alien species while preserving native animals and plants. The best solution depends on what the ecosystem was like prior to the introduction of the invasive species and on how the invasive species threatens local flora and fauna.

Here are a few examples of initiatives taken against invasive species.

Asian Carps in The Great Lakes

Asian carps have been present in the Illinois waterways for years. Ecologists are currently worried about three species of Asian carps taking over the Great Lakes.

Asian carps are an invasive species because they don’t have any natural predators in North American waterways and eat the phytoplankton and zooplankton that other native fish species need to survive. This invasion is a threat to several native species and for the Great Lakes fishing industry.

This invasive species is currently contained thanks to underwater electric barriers, but some fish manage to get through. There are other projects being developed to stop Asian carps. One of these projects consists in installing an acoustic fence on the bottom of the lakes. This acoustic fence would emit sounds that only the carps can hear but would be harmless to native species.  

The Amphibian Problem

Non-native amphibians are typically introduced to a new area for pest control purposes, but some frogs and toads are also inadvertently introduced via the pet trade or imports. Amphibians can reproduce very quickly and compete with local species for food sources.

American bullfrogs, cane toads, and Cuban tree frogs are considered as invasive species in the U.S. Brazil is currently seeing ecosystems threatened by six different species of amphibians and things could get worse.

Bullfrogs are particularly problematic. A female can lay as many as 20,000 eggs and these frogs easily adapt to a wide range of environments. Bullfrogs can eat birds, lizards, fishes and even snakes.

Controlling amphibian populations could become easier thanks to a study that looked at how cane toads reacted to different types of light. The study found that traps with ultraviolet lights attracted more toads and that toads tended to avoid fluorescent and incandescent lights.

These findings could help control amphibian populations with traps and keep frogs and toads away from certain areas by adding fluorescent or incandescent lights. Unfortunately, these findings aren’t used on a large scale to control amphibian populations.

Invasive Plants Are a Worldwide Issue

Non-native species like the floating pennywort, Azolla fern or the Japanese knotweed are wreaking havoc on British ecosystems. In fact, there were 3,000 non-native species present in the wild in the UK in 2005. Two-thirds of these species are plants.

This isn’t an isolated issue. Kudzu, a vine native to Japan, is smothering vegetation throughout the Southeast of the U.S. Invasive algae is an issue that threatens coral reefs and fishing industries worldwide.

The UK has launched a program that consists in educating people about invasive species and how they spread. The British government also created a special rapid response unit tasked with tracking the progression of invasive species and in taking action as early as possible to repel or control these species.

Global Warming Is Creating an Environment Favorable to Invasive Species

Plants and animals have always migrated to other areas and become a part of new ecosystems as a way of adapting to changing conditions. However, human activity is behind most invasive species.

Some invasive species end up in a different area because of stowaways in shipping containers. The pet trade is also responsible for the introduction of non-native species in new areas, and importing alien species to grow feed for animals or pest control purposes can result in an invasion.

Global warming is also reshaping some ecosystems and creating a warmer environment in several areas of the Northern hemisphere. Exotic species are often a lot more adaptable and will bloom earlier than their Northern counterpart thanks to rising temperatures linked to global warming. These species also benefit from the lack of natural predators in Northern ecosystems.

How to Stop Invasive Species

Invasive species are a serious issue. Non-native plants and animals might not sound like something that would directly have an impact on your life, but the increasing presence of invasive species could create a world where the ingredients for your favorite meals become difficult to find, or where native species that are common to your area become extinct.

Governments around the world need to take action to maintain diverse and healthy ecosystems. Monocultures are common in agricultural areas, but mixed forests would be a better way to sustain local ecosystems. There should also be programs to introduce natural predators to stop invasive species and some efforts made to protect some native species.

And because global warming is a part of the equation, everyone should make efforts to reduce their use of fossil fuels. Pollutants and insecticides should also be avoided since these chemicals can harm native species and cause alien species to adapt, become more resistant and spread at a faster pace.

Everyone can do something against invasive species. You can learn to identify the non-native species present where you live, clear your backyard of any invasive plants, and create a diverse ecosystem on your property.

If nothing is done, the ecosystems we grew up with could change forever. The flora and fauna we associate with the places where we live could disappear forever and be replaced by exotic species.

Author:  Dakota Findley

Janssen Cares Volunteer Day

Volunteers from Janssen Pharmaceuticals pulled on their work gloves and hefted trimmers, loppers, and chain saws to work with members of Friends of Princeton Open Space (FOPOS) recently. Their task was to get a start on ridding the area along the driveway of the Billy Johnson Mountain Lakes Nature Preserve in Princeton of some stubborn invasive species.  


After a quick lesson by FOPOS Natural Resource Manager, Jeff Geist, in identifying the most prevalent invasives, (honeysuckle, grapevine, porcelain berry, and multiflora rose), the eight Janssen personnel enthusiastically tackled their assignment, undeterred by poison ivy and two areas of ground-nesting yellow jacket wasps.  In record time 250 linear feet on both sides of the driveway had been cleared.

Clark Lennon, FOPOS board member and supervisor of the day’s work, said he was impressed by the Janssen crew.  “I never thought we would get this much accomplished in just a few hours”, he said.  “They worked really hard and did a great job.”

FOPOS plans to remove invasive species along the full half-mile length of the driveway into the Nature Preserve with the help of volunteers and board members. This work complements the 18 acre forest restoration project on the west side of Mountain Lake which FOPOS has also undertaken.


Friends of Princeton Open Space is always interested in partnering with corporate groups who are looking for volunteer opportunities.  For more information, contact us at

Woodfield Reservation Update

This summer, the FOPOS Trail Crew has been hard at work restoring and repairing the trails at Woodfield Reservation.  Last year, the crew cleared several thousand feet of trails to make it walk-able.  This year’s project has been constructing boardwalks over swampy and wet trails.  Thus far, in June and July, the team had 9 workdays with a total of 14 volunteers resulting in 162 work hours, 360 feet of constructed boardwalks and 130 feet of relocated trails.


If you are interested in helping our volunteer crew for the remainder of the summer, and into the fall, please email us at 

FOPOS Hosts Princeton YMCA Outdoor Living Skills Camp

The Friends of Princeton Open Space hosted 36 kids from the Princeton YMCA Outdoor Living Skills Camp on Tuesday, July 18 from 10:00-2:00.  During their time here, the campers learned about, and practiced, Leave No Trace, the set of guidelines for all hikers, campers, etc.

 FOPOS Natural Resource Manager, Jeff Geist, and two summer interns, Anna Korn & Katrina O'Donnell, guided the group around the property.  During their 2 mile hike, the kids learned about tree identification, how to identify edible plants (they all loved wineberries), and the guides helped them with bird and other animal identification.  We rounded out the hike with butterfly and other bug collecting at the Tusculum Meadow.  

The group then enjoyed lunch at Pettoranello Gardens, followed by a brief lesson on outdoor first aid.  Finally, the group all created key chains to remind them of the 7 Principles of Leave No Trace. 

TIAA EarthShare NJ Corporate Green Challenge

On April 7,2017, TIAA Financial Services of Princeton, NJ participated in EarthShare's Corporate Green Challenge.  A large group of volunteers came out to the Mountain Lakes Preserve to assist in the construction of a deer fence.  The area was previously clear-cut in order to stage equipment for the restoration of the Mountain Lakes dam.  After the restoration was completed in 2012, the area was planted with native trees and shrubs. A deer fence was installed to prevent harsh deer browse on the newly planted natives.  After many years, the fence was in need of replacement.  That is where TIAA came in. 

A Day in the Mud

It was an interesting change from what has become a frequent pastime of building boardwalks everywhere.  A hardcore group of volunteers including Chris Coucill, Van Williams, Richard Meyer, Bob Shull, Clark Lennon and Ted Thomas finally got to work on a bridge at Roger's Refuge, which had slipped its footings and floated away. 



Successfully flipped. 

Successfully flipped. 

Fortunately, it was also able to float back, with a little urging.  After quite a bit of dragging, prying, lifting and flipping, it was back in place and ready to face the next flood.  During the project, the group suffered 3 casualties: Clark, Van and Bob (pictured), in that order, slipped on a very slippery slope, and later had to be helped to their feet.

Man down!

Man down!

A good days work. 

A good days work. 

How to Get Lumber Up a Hill

In a massive logistics operation reminiscent of D-Day, the FOPOS trail crew recruited a small army and provided it with the necessary equipment (work gloves, water, bug spray) in order to move the vast quantity of materials needed for building infrastructure uphill and into position for the coming Woodfield Campaign.  The temperature was around 95 degrees, the army was primarily 9th grade girls (9) and boys (3) from PDS.

The crew.

The crew.

The materials were 80 2x10x8 foot planks and 120 4x4x2 foot cross ties needed for the planned construction of 320 feet of new boardwalk to accompany the 220 feet installed last summer.  Although this project was not officially part of the work covered by last year's ANJEC grant, we were persuaded by this year's floods that many more feet of boardwalk were needed.

The materials to be moved.

The materials to be moved.

Hitching a ride and taking a break.