Beyond Kudzu: Can Non-Native Species Benefit an Ecosystem?

Sept. 12, 2016

If you’ve worked on a project that calls for revegetation using native seeds, or if you’ve ever dealt with an area that’s overrun with an invasive species like the tenacious kudzu vine—considered a noxious weed in the US—you likely have an opinion about the introduction of non-native species to an ecosystem. The list of flora and fauna run amok is a long one. This article from the Wall Street Journal, “Invasion of the Alien Species,” lists some of the more notorious non-native species that have caused problems across the globe: “In the Mississippi River, it is Asian carp; in the Everglades, Burmese pythons; in the Great Lakes, Russian zebra mussels; in the South, Indochinese kudzu vine. In Australia, cane toads from South America; in Lake Victoria in Africa, water hyacinth from the Amazon; in Germany, Chinese mitten crabs; in the Caribbean, lionfish from the Pacific. A fungus spread by African clawed toads (used in laboratories) has wiped out frogs in Central America.” And the list continues of native plants and animals that have been virtually wiped out by thriving non-native species that either kill them outright or simply outcompete them for scarce resources.

Non-native species often thrive because they have no natural predators in their adopted environment. One solution, the article notes, is to bring in predator species from the invader’s native environment, or from some other environment, to control them. Also known as biological control, it seems like an obvious solution, but much can go wrong, as we’ve occasionally covered in Erosion Control. For example, the US Department of Agriculture released salt cedar beetles from Kazakhstan in Colorado to control the invasive tamarisk, or salt cedar, shrubs that had once been imported to plant as windbreaks and control erosion, but which eventually crowded out native plants like cottonwood trees. The salt cedar beetles began killing not only the tamarisk but also other plants critical for the survival of endangered birds.

The WSJ article suggests, though, that non-native species aren’t always a bad thing, that they can increase biodiversity in their new home and create additional benefits. Zebra mussels, it points out, have effectively filtered the water of Lake Erie and made it clearer, and in the Southwest the tamarisks—which are still there, despite the efforts of the salt cedar beetles—have become preferred nesting sites for the willow flycatcher, one of the region’s endangered birds.

While globalization and increased movement of people and goods around the world have made it easier for non-native species to reach new habitats, scientific advances are allowing us to reverse the process in many cases. Vaccines that cause sterility—and which can sometimes be administered in food—can sterilize members of an invasive species; there is hope in Great Britain that this technique might eliminate the gray squirrel, which has crowded out native rodents. Genetic manipulation of the Aedes mosquito is being used to battle the Zika virus in parts of Brazil; modified male mosquitoes released into the environment father larvae that will not reach maturity, thereby reducing the overall mosquito population.

Have you worked on a project that’s using biological controls to curb a non-native plant or animal species? Under what circumstances do you think introducing one species to control another is warranted? How about the use of widespread vaccination or genomics?

Continuing Education

Here are some upcoming webinars—two of them free!—from Forester University that will be of interest to erosion control professionals.

Designing for High-Flow with Concrete-Enhanced Synthetic Turf—Free Webinar

September 27

Speaker Bradford Cooley, P.E., discusses applications of concrete-enhanced synthetic turf (CEST) revetment systems, design and installation best practices, hydraulic and non-hydraulic performance results, and how you can implement CEST at your site to improve performance and reduce maintenance costs. Sponsored by Watershed Geo.

Click here for more information and to register.

Specifying Engineered Soils for Sustainable Vegetation—Free Webinar

October 26

Returning speaker Marc S. Theisen, CPESC, CPSWQ, CESSWI, discusses how to specify Engineered Soil Media (ESM) as a cost-effective alternative to topsoil, compost, and other conventional organic soil amendments. Topics include testing your soil for organic content, selecting proper ESM application rates, calculating the cost benefits, and applying the best practices from real-world case studies and research. Sponsored by Profile Products LLC.

Click here for more information and to register.

Fire and Rain: Post-Fire Erosion Control Master Class Series

October 6 – November 3

This five-part master class series covers post-fire erosion control applications, techniques, and best practices, including post-fire hazard assessment, secondary disaster impacts, watershed hydraulic changes, remediation access and funding, post-fire BMP selection and implementation, accountability issues, and emergency measure implementation. The five live and on-demand lectures are followed by open Q&A sessions. Speakers include Mike Harding, Julie Etra, Ian Paton, Andrew Earles, and Kathleen Harr.

Click here for more information and to register.

About the Author

Janice Kaspersen

Janice Kaspersen is the former editor of Erosion Control and Stormwater magazines.