This investigative series follows my personal exploration into a big question. Is the toxic chemical war we are waging on invasive plants doing more harm than good? To read the introductory forward to this post click here.

Invasive Plants: Noxious Enemy or Remedial Friend?

Environmental journalist Fred Pearce was once a do-good invasive fighting conservationist. But after years spent reviewing the emerging research presented in his book The New Wild: Why Invasive Species Will Be Nature’s Salvation, Pearce concluded that the current view of invasives as aggressive interlopers spoiling pristine, natural ecosystems is based on “outdated intellectual sources”.

Instead Pearce claims, new evidence suggests that introduced alien species usually die out or settle down to become model eco-citizens. But in the meantime, Pearce writes that “far from being nature’s destroyers, aliens may be its reinvigorators, its salvation”…they are “natures best chance of healing the damage done by chainsaws and ploughs, by pollution and climate change.”  

Yet according to The National Invasive Species Council, invasive plants are far from our friends. They are “an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health.” But many prominent scientists, biologists and conservationists disagree. 

The esteemed evolutionary biologist Stephen Jay Gould wrote in this article, published in Harvard University’s Journal Arnoldia that the “romanticized notion that old inhabitants [natives] learn to live in ecological harmony with surroundings, while later interlopers tend to be exploiters” is “romantic drivel.”

This article in Yale Environment 360 explores the dissent among biologists when it comes to the long-held orthodoxy that alien species are inherently bad. “In their contrarian view, many introduced species have proven valuable and useful and have increased the diversity and resiliency of native ecosystems.”

And in this essay, “Don’t Judge Species on Their Origins,” in the journal Nature, over twenty conservationists agree that “Policy and management decisions must take into account the positive effects of many invaders,” and they advocate that these decisions be based on “sound empirical evidence and not on unfounded claims of harm caused by non-natives. Another valuable step would be for scientists and professionals in conservation to convey to the public that many alien species are useful.”

And yet, as Andrew Cockburn’s fascinating article in Harpers Magazine titled Weed Whackers: Monsanto, glyphosate and the war on invasive species reveals, “It is the official position of the federal government, as expressed by the State Department, that “invasive alien species pose one of the most serious threats to our environment, affecting all regions of the United States and every nation in the world.” And it means that “Last year, the federal government spent more than $2 billion to fight the alien invasion, up to half of which was budgeted for glyphosate and other poisons.”

This figure attests to the gargantuan use of pesticides and herbicides on invasive plants in the US alone, never mind Canada and the rest of the world. Just how the science of invasion biology came to be, and how it is deeply entwined wth the chemical industry – are explored in the next post. (see here)

So is this chemical war on invasive plants warranted? Are invasive plants our foes or our friends?  Obviously there is already a great deal of information out there about why invasives must be eradicated, so I won’t spend time on it here. But lets explore some of the latter evidence.

Herbalist Timothy Lee Scott , author of Invasive Plant Medicine: The Ecological Benefits and Healing Abilities of Invasives agrees with the views put forward by Pearce.

He believes that the view of invasive plants as disruptive “is no longer supported by a scientific, ecological understanding of plant dynamics within complex eco-systems”. Scott’s book compiles a wide variety of studies demonstrating that many invasive plants are actually cleaning up the mess we’ve left behind, healing damaged landscapes, breaking down and eliminating toxins, renewing and restoring degraded soil and waterways. 

Scott writes: “Imagine a forested landscape that has recently been cleared of all the trees and plants that have commingled there for hundreds of years. Bare earth is revealed, watercourses changed, and all species, both visible and invisible, have felt this trauma. Delicately layered soils are fractured and opened. They then have to make adjustments to cope and begin to rejuvenate the environment that has been upturned…”

Scott continues, “…nature does not wish to expose the soil; it always tries to cover it with plants. These plants fill in all spaces that provide sunlight; they access different degrees of brightness on all planes of plant structure, from the soil to the forest canopy… Each has an innate form and function to help fill in the gaps and rehabilitate the devastated area…The incredible ability of pioneering species to cover wounded landscapes in such prolific numbers makes them easily misunderstood as invasive intruders.”

The succession of pioneer plants (many of which are defined as invasive species) prepare “the soil for other species to follow, first by protecting land from further erosion, then by enriching the soil with large quantities of biomass and providing essential nutrients with uptake capabilities; and finally by balancing microbes in the soil ecology.”

Boyce Thorne Miller (Science and Policy Coordinator of the Northwest Atlantic Marine Alliance) argue that much of the “scientific” evidence that is typically used to describe ecological harm can be equally interpreted to indicate ecological benefits. Her presentation at the 32nd National Pesticide Forum, April 11-12, 2014 at Portland State University, presented evidence that many “invaders” like Cordgrass have been shown to be important for revitalizing damaged ecosystems, repairing depleted soils, cleaning up toxics, and are essential for creating and maintaining biological diversity.

With this in mind, it could be suggested that invasive plants are not evil marauders intent on colonizing and dominating local eco-systems.They are prolific because they are a response to our relentless development and urbanization. As we merrily mow along chopping down the trees and upturning soils – mother nature is right beside us, sending more and more ‘weeds’ to repair the damage we’ve done.

Scott’s book proposes another startling radical idea – that nature is not only seeking to heal her landscapes – but the life forms that inhabit her. Scott suggests that in the wake of environmental devastation and diminishing plant life, mother nature quickly responds by providing highly nourishing and healing foods to the animals which depend on her sustenance. And that includes us.

He writes: “The deteriorating health of our forests is analogous to the current weakening of the human immune system…People, like the earth itself, are overburdened with toxic and infectious burdens, and all ecosystems cope with poisoned and traumatized influences”. So Scott sees it as no coincidence that nature provides us (and wildlife) with prolific nutrient foods packed with deeply healing medicinal components.

Scott also cites research conducted by author and esteemed herbalist Stephen Buhner who believes there may be a “medicinally significant connection between pandemic plants and diseases”. While researching plant candidates for treating Lyme disease, Buhner discovered that Knotweed (currently the number one target of conservation groups like the Coastal Invasive Committee) had spread throughout North America in nearly the same trajectory and at the same rate as Lyme disease. Buhner’s research suggests that Knotweed’s potent properties as an antimicrobial (amongst many others) makes it a useful treatment for emerging diseases such as Lyme, West Nile encephalitis, SARS, hepatitis C, HIV”.  

Are we poisoning the very plants that nature has sent to help nourish and heal us? In her article Re-Thinking Invasive Plants, herbalist Rose Barlow wrote “Noxious weeds” like dandelion, burdock and garlic mustard are nutritional powerhouses that offer themselves to us humans in super-abundance to help us to nourish our depleted bodies, leach environmental toxins, and otherwise help us to cope with our industrialized world. Yet instead of receiving the gifts these plants bring with them, alien species are villanized and portrayed as terrorists.”

By allowing invasive plants to thrive – is nature making a mistake? Claude William Genest of Green Mountian Permaculture Institute has written ” The Nobel prize-winning “Gaia Theory” teaches us that the earth is like a body: it self-organizes, self-repairs, and self-reproduces. It is a single, self-regulating living system that organizes itself in such a way as to maintain and create the conditions that are suitable for life…Similarly, invasive plants are also operating in the context of the whole-system. Take a closer look: they are absolutely specialized at cleaning up our mess.”

So who truly knows best? Us or mother nature? Are our conservationist efforts to restore local eco-systems to their original ‘natural’ state doing more harm than good? The jury may be out on whether or not in the long run we are hindering mother nature’s remedial processes, but I’m pretty sure applying millions of dollars worth of toxic chemicals to our landscapes each year fits the definition of harm – right now.

All told, their widespread use in our city and provincial parks, our highways and byways, truly boggles the mind – and just how widespread they are, will be the subject of another post. So I have to say, from where I sit, it looks like the definition of invasive plants as “likely to cause economic or environmental harm or harm to human health” better describes our own activities and impact on the landscape.  

In Part Two I’ll further explore why some believe that the sacred heart of conservation ecology – that invasive plants are destroying pristine natural environments, ‘endangering’ indigenous eco-systems and disrupting our attempts at ‘restoration’ – may be shortsighted. 

Resources:

• The New Wild: Why Invasive Species Will Be Nature’s Salvation 
• Weed Whackers: Monsanto, glyphosate, and the war on invasive species
• Invasive Plant Medicine: The Ecological Benefits and Healing Abilities of Invasives
• Beyond the War on Invasive Species: A Permaculture Approach to Ecosystem Restoration
• Where do Camels Belong: Why Invasive Species Aren’t all Bad
• Invasive Species Aren’t The Actual Problem, They’re a Symptom
• Invasion Biology: Critique of a Pseudoscience

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