The Changing Conversation Around Invasive Species

Recently, the debate about invasive species has become more polarized than ever, with a degree of defensiveness and anger not seen previously. The reasons for this are many, some difficult to admit to.

Chinese Clematis may be invasive, but it deserves a less bigoted name.

I attended a webinar a few weeks ago in which the presenter asserted that “invasive species” is a “militarized term.” My instinctive reaction was that this was accusatory, bordering on defamation of science, when there is clear evidence that the introduction of a species to a new ecosystem can have devastating consequences.

Spongy Moth is still a bonafide forest pest, but now has a more appropriate moniker.

Pondering his comment further, it occurred to me that most of the animals, and plants, we label as invasive have some sort of obvious and negative economic impact. We have, as a consumer culture, become conditioned to frame everything in terms of business and monetary interests rather than ecological concerns. This has become more complicated by angst over climate change, and the resulting vulnerability of humanity to emerging threats, be they viruses or “murder hornets.”

© Yasunori Koide and Wikimedia Commons. Asian Giant Hornet only "murders" in the beehive, but is a serious threat to apiculture because of that proclivity.

The sudden, and/or overwhelming appearance of a novel organism is going to cause alarm, and the public seldom has comprehensive, appropriate knowledge for interpretation of potential impacts. We are at the mercy of what news outlets tell us. Because traditional print, radio, and television media now compete with social media, sensationalism is the order of the day. “Click bait” banners prevail over more accurate but less provocative headlines.

© Kim Fleming and Bugguide.net. Joro Spider, Trichonephila clavata, is not currently considered invasive.

Initial forecasts can also be premature. The jury is still out on whether some recently-introduced species will become problematic. They may not. The Joro Spider is a case in point. It is locally abundant in some parts of the southeast U.S., but whether this translates to a displacement of native spiders remains an unanswered question.

We collectively have a fascination with heroes and villains, too, and there are no more menacing villains than alien-looking insects, spiders, and other arthropods. Fantasy melds with reality and it becomes difficult to separate the two if you are not scientifically literate, or have a business model that demands public hatred of a particular creature.

© USDA ARS, public domain. Spotted Lanternfly, Lycorma delicatula, adult and nymphs. This species is a potential agricultural pest of serious magnitude.

In opposition to nativism is the idea that there is no such thing as invasive species. After all, man is part of nature, and therefore our actions are natural processes. The outcomes of those activities are circumstances to which we, and other species, will adapt.

It may be no coincidence that a backlash against the idea of invasive species is more evident now that we are recognizing, and attempting to mitigate, a history of colonialism. A convincing argument could be made that White settlers are the original invasive species. Here, in North America, we annihilated and displaced Indigenous members of our own species. We enslaved others. To this day we continue missionary work and other forms of colonialism. Therefore, the idea of invasive species becomes one of self-loathing, certainly an eventual threat to White supremacy and privilege. White people do not want to see themselves as villains.

Meanwhile, we demonize human immigrants and refugees as criminals and threats to domestic labor pools. We clamor for the closure of borders to our fellow humans, but allow our boundaries to be permeated by everything else. Not that human-imposed boundaries reflect natural ones.

The Cross Orbweaver, Araneus diadematus, is an example of a naturalized arachnid in North America.

Scientists have an uphill battle in resolving these opposing perspectives and initiating constructive dialogue. Looking to the past we see how some species from foreign lands have become “naturalized” over time, becoming innocuous additions to our flora and fauna. The average citizen may be shocked to learn that dandelions are not native to the U.S. They have become a fixture in our lawnscapes, even if we are instructed to use weed-killers against them.

Myrtle Spurge, aka "Donkeytail," Euphorbia myrsinites, is classified as a noxious weed in some jurisdictions, but not everywhere.

What is lost in all of this is attribution of the modern problem of invasive species to global consumer culture. Historically, human colonists brought other species with them as a guarantee of food and other necessary resources when venturing into unknown territory. Soon after, those species and their products became valuable in trade, a way to establish meaningful and positive relationships with Indigenous peoples, or other settlers. The pace of travel was slow, and the scale of enterprise miniscule compared to twenty-first century business.

Today, we mostly covet plants and animals of far-off lands. Plants, especially, can harbor potential insect pests. Thecontainers used to transport international commerce are frequently occupied by insects, rodents, and other organisms. We seldom make that connection between our consumer habits and the state of ecosystems around the world.

Captive Reticulated Python. Release of unwanted Burmese Pythons into the Everglades by irresponsible pet owners has been....problematic.

We cannot turn the clock back, but we should make more informed and conscientious individual choices in the marketplace. We should promote the welfare of Indigenous peoples, and actively seek their counsel and leadership in crafting a world better able to withstand climate change. A permanent end to colonialism would not be a bad thing, either.

In Praise of "Weeds"

You have been sold a bill of goods if you believe that all "weeds" are created equal. Weeds is in quotation marks because the majority of what we call weeds are simply native wildflowers and grasses that volunteer themselves in our carefully orchestrated urban and suburban landscapes. Allow me to explain.

A primrose sprouts defiantly from a sidewalk crack

We create villains to open opportunities for the invention and marketing of products and services to kill them. Meanwhile, the actual villains are exotic plants propagated by the nursery and landscaping industries, which then escape cultivation to wreak havoc on natural ecosystems. Everybody in the business sector wins, but you are out of pocket for a good deal of expense, and natural habitats are abused or at least compromised, in the process.

Lawn services and weed killers should be trending down by now

This is not a conspiracy as much as it is a marketing strategy that has gone so far as to encourage legislation of local municipal ordinances that may explicitly prohibit homeowners from allowing their property to revert to any semblance of a natural ecosystem. Ostensibly, these "nuisance laws" were created in an effort to ensure public health and safety, seeking to eliminate refuges of "vermin," pests, pathogens, and excessive pollen, and mitigate fire risks. The stereotypical weed ordinance is one which prohibits grasses or brushy vegetation to exceed a specified height. The junk vehicle discovered while mowing the lawn is a running joke.

Home Owners Associations (HOAs) have taken this to a whole new level, with their attention to minutiae rooted in preservation and enhancement of property values. In the case of the authority my spouse and I are under with our townhouse, this has resulted in removal of some trees, replacement of juniper hedges with rock substrates, and continued embracing of water-guzzling lawns. Keeping up appearances means more to these organizations than enhancing the health of local ecosystems.

Clover is a bee magnet and fixes nitrogen: Win-win!

What we should be doing is advocating what I call "weed tolerance." Even naturalized plants have their benefits. Dandelion is among the first plant to bloom in spring, offering a vital nectar and pollen resource to butterflies, bees, and other insects when nothing else is flowering. The clover in your lawn is a bee magnet, plus the plant is fixing nitrogen so you don't need to fertilize as often, if at all.

Ok, Chinese Clematis is a genuine noxious weed

In fairness, there truly are weeds that have no place in the landscape. You can find them as state-listed noxious weeds. The United States Department of Agriculture has conveniently compiled a database of these most-wanted (maybe most-despised is a better term) plants for you to use in determining which plants you need to eliminate from your yard and garden, or avoid when shopping for plants. This is an ever-changing list as more information is gathered about the impact of each commercially available plant. It was not until recently that Bradford Pear and Butterfly Bush (Buddleja davidii) became enemies instead of friends in the landscaping community. Keep tabs on the list for more additions.

Wild rose, with more open blossoms, is friendlier to bees than cultivars are

Increasingly, more attention is being paid to providing for native pollinating insects, and supplying breeding birds with the insects necessary to raise a brood of chicks. You can search endlessly online for resource after resource, but you may wish to start with books like Bringing Nature Home, by Douglas Tallamy. Dr. Tallamy and his colleagues and students have worked tirelessly to demonstrate conclusively the differences in ecological impact between native plants and exotic plants. Native plants, including many species we currently define as "weeds," sustain far more species of insects and other wildlife, as they are already adapted to soils, precipitation, and other variables where they thrive naturally. This makes the plants hardier, better able to withstand heavy impacts from herbivores, diseases, and other agents that affect plant health.

Yellow and white composites are favorites with bees and butterflies

Want help that is even more localized and informative? Join your state's Native Plant Society. Here is a list of them in the U.S. and Canada. Also avail yourself of the Cooperative Extension Service, typically associated with your state's land grant university. There is usually at least one office in each county, located in the county seat.

The tide does appear to be turning, even with those weed ordinances. While some cities have begun relaxing their codes, other municipalities have reversed course completely, actively encouraging citizens to "go native" with revised laws and financial incentives. Use these success stories to argue your case locally for similar innovative strategies.

Don't forget about evening- and night-blooming flowers like blazingstars when landscaping

Lately I have been enjoying the weeds that have been flourishing here in Colorado Springs thanks to an exceptionally wet, cool spring. There are flowers blooming that I have never seen before now. How do I translate my appreciation for vegetative rebellion into something meaningful to those who have bought into the neat and tidy vision of the marketplace?

Penstemon growing in a vacant lot in Colorado Springs

Bullfrogs

I haven’t been to the Campus Pond at the University of Massachusetts in many weeks now, but back on June 8 I was treated to a large, very cooperative amphibian as a photo subject during my lunch hour. The bullfrog, Rana catesbeiana, is native here, but elsewhere in North America, where it has been introduced, it might better be called the “bully” frog.

The species is named for the early English naturalist Mark Catesby who explored the southeast United States in the early 1700s, documenting his findings in words and illustrations published as Natural History of Carolina, Florida, and the Bahama Islands. Just like its human namesake, the frog has had “legs” to parts of the world far removed from its native eastern U.S. haunts.

It has, in fact, been those meaty hind legs that have caused the dispersal of the bullfrog around the globe. Prized as a delicacy, frog legs are a staple appetizer on many a restaurant menu. It is far less expensive to harvest the amphibians locally than to import them, so consequently the bullfrog was introduced to various new territories including the western U.S. and British Columbia, Cuba, Jamaica, Mexico, South America, Europe, Asia, even Hawaii.

That humans prey on bullfrogs, along with herons, raccoons, snakes, and other animals, is not enough to mitigate the effects of what the bullfrogs themselves eat: which is nearly anything and everything. Where bullfrogs have been introduced, native wetland fauna can suffer dramatically.

Bullfrogs have been at the least implicated in the decline of the western pond turtle in the Pacific Northwest (they eat the hatchling turtles), the Mexican garter snake in parts of Arizona, New Mexico, and Mexico, and native frog populations in California.

Any animal smaller than the bullfrog is fair game, though, and even tarantulas are on the menu, along with various large insects, small rodents, and birds.

I have a hard time now hearing that deep bass call of “jug-o-rum” without cringing a bit. Every organism surely has its place, but when Homo sapiens extends the boundaries of place for an animal like the bullfrog, all hell can break loose in the aftermath.

Big Bad Giant Cane...No, Giant Reed!

I wanted to publish a blog entry on giant cane, a plant that has been deemed an invasive species here in Arizona, but could only find glowing descriptions of that native bamboo, with no state west of Texas being in its range. Silly me, I got confused between giant cane, a largely beneficial domestic grass, and giant reed, apparently the epitome of foreign evil.

Who can fault me? As if the common names aren’t confusing enough, even the genus names are nearly identical: Arundinaria for giant cane, and Arundo for its reed counterpart. The similarities seem to end there.

Giant reed, Arundo donax, is thought to be native to east Asia, but has been so widely cultivated, for thousands of years, in that region, southern Europe, northern Africa, and the Middle East, that its point of origin is difficult to ascertain. The plant was (surprise, surprise) imported to North America as an ornamental from the Mediterranean. It arrived in Los Angeles sometime in the early 1800s. Its popularity ensured its spread, and it now occurs in feral populations across most of the southern U.S. north to Missouri and West Virginia.

What is a wetland plant doing in our Arizona desert? Deep roots can reach water tables near the surface of even ephemeral watersheds. Once established, two- to three-year-old stands of giant reed are remarkably drought-resistant. North American populations reproduce via rhizomes that sprout clones stretching over several acres in some cases. The rhizomes themselves can assume the form of dense mats over a meter thick. Flooding events break off chunks of those mats, and carry the species to new territories downstream.

Giant reed appears to have almost no redeeming qualities. Unlike the native cane, giant reed is not palatable to livestock or wildlife. It is, in fact, full of vile, poisonous compounds like cardiac glycosides, sterols, and alkaloids.

Further, giant reed is arguably a fire hazard, and it is for this reason more than any other that its presence causes so much consternation. Not only can it fuel a wildfire, but the plant won’t be killed in the process. There are accounts of scorched rhizome mats sprouting new shoots two feet high only two weeks after some California fire events.

So, is it any wonder that there is even a volunteer army dedicated to ridding Tucson of this botanical menace? Just check out the Tucson Arundo Removal website for more information. See also the U.S. Forest Service Plant Database, where I gleaned much of the information for this profile. Is it giant cane or giant reed? Donax, don’t tell I say.