The topic of invasive plants can be a prickly one. Burning Bushes, Barberry Bushes, Callery Pears, and Asian Honeysuckles are very popular landscaping choices as are the latest plants that the horticultural industry is selling, most of which have been imported from other continents solely for decorative purposes in a yard. Invasives do not understand property lines. The problem is that they while they may look lovely and innocent, they actually wreak havoc once they find their way outside of a yard. They spread, they change the soil chemistry, they shade out native plants, they do not support other animals. Elizabeth Kohlbert in her recent book Sixth Extinction: An Unnatural History calls this introduction of non-native invasive species, the new Pangea.
You can still buy many of these plants which are costing us billions of dollars as a nation to remove, and in effect (to be blunt but honest), starving other animals. Some recent research also suggests that invasives play roles in harming human health, beyond the long-term threat that the loss of biodiversity means for humans (Barberries harbor Lyme-infected ticks and a new study looked at the complex relationship between leaf litter and Culex pipiens mosquitoes (the ones that carry West Nile): http://phys.org/news/2015-07-landscape-west-nile-virus.html or http://conservationmagazine.org/2015/07/to-stop-west-nile-go-native/).
The presentation by Mia Spaid addressed issues about the cost of removal and management in order to mitigate the threat to local ecosystems because the problem with invasive species is that they spread prolifically and aggressively, out-competing our native plants. Some may say, well, evolution will kick in; survival of the fittest. This notion sounds okay, but it is inaccurate. Evolution takes millions of years, not 100 or 200 years. These introduced species did not evolve here, so they have no natural enemies or predators or pathogens to help keep them in check. For example, Garlic Mustard was brought to the U.S. as a foodstuff by the colonialists, but its vigor has surpassed what the colonialists probably intended. It destroys our woodlands; in those woodlands, our beautiful ephemerals are not able to thrive nor able to reproduce, and the same fate is spelled for our shrubs and trees. Our global connectivity has only made the transmission of invasives more possible, but now we know what can happen, and can take steps to prevent further introductions.
Part of the Solution is Us and Our Choices:
One of the most important things we can do is to remove invasive species in our own yards. Suburban landscapes are overwhelmingly planted with invasive plants. If you go to natural areas, though, that are not part of the preserve system, you will see what happens when invasive plants leave our yards, towns, and villages. A woodland that is slowly becoming nothing but barberry bushes on the forest floor. Honeysuckle thickets line trails. Callery Pear trees or Buckthorns are the only trees represented in a farm’s windbreak. Removing invasives from our own properties is an environmentally responsible thing to do.
In order to avoid the accidental introduction of invasives, the best course is to make an informed choice and to plant native plants. Ms. Spaid gave us many alternatives to invasive species. The reason that people plant so many invasives is because they are cheap to reproduce so are readily available at nurseries. Horticultural introductions go through very little regulations–their potentials for becoming invasive plants–are never properly studied. Do not assume if something’s available for purchase at your garden center it is harmless. If people stop buying these plants, they won’t be sold.
Here are just a couple of invasives with alternative native plants: Instead of Burning Bush, try Eastern Wahoo (Euonymus atropurpureus), Black Chokeberry (Aronia melanocarpa) or native (non-cultivar) Viburnums (Viburnum prunifolium or Viburnum lentago), all of which have ecological benefits that far surpass Burning Bush. Callery Pear is a popular invasive ornamental planted for its spring blooms. Serviceberries (Amelanchier arborea or Amelanchier laevis) or Hawthornes (Crataegus spp.) are good native choices and have further benefits because they produce fruit and support wildlife. Here is a helpful site that lists alternatives to invasive species: http://grownative.org/native-plant-info/alternative-species/. Double check that a plant you are interested in is from your local area, and if you purchase it, then check that it is from local stock (local eco type).
There are many reasons to care about invasive plants and to do what you can to prevent the introduction and spread of them. If you are still unsure, please see this pamphlet: http://bugwoodcloud.org/mura/mipn/assets/File/InvasivesBrochure.pdf
Mia referenced many materials we can use to identify and prevent invasive species. There are books that can help with selection of native replacements for invasive species (Native Alternatives to Invasive Plants, Brooklyn Botanic Guide), and now there is an app available from Midwest Invasive Plant Network, so when you are out shopping, information is available right on your device (smart phone, iPad, etc): http://apps.bugwood.org/apps/landscape-alt/
There are Citizen Science opportunities as well in which you can help scientists, ecologists, and land managers react quickly to new invasive species. If they are caught early, their destructive influence can be efficiently removed. http://www.newinvaders.org/ or https://www.eddmaps.org/ (apps also available).
Websites: Northeast Illinois Invasive Plant Partnership, www.niip.net or Midwest Invasive Plant Network www.mipn.org or University of Georgia Center for Invasive Species and Ecosystem Health www.invasive.org.
The Midwestern Native Garden http://www.amazon.com/The-Midwestern-Native-Garden-Alternatives/dp/0821419374
Native Alternatives to Invasives http://www.amazon.com/Native-Alternatives-Invasive-Plants-Greener/dp/1889538779
More information from Wild Ones National: http://www.wildones.org/learn/native-plants-natural-landscaping/