Changing plant communities at the local scale are symptomatic of the changing climate globally. Patterns of temperature, precipitation and seasonal timing are shifting, and with them, the patterns of birth, growth, reproduction—and survival—of all living creatures.
One widely observed syndrome is “season creep,” in which Spring has been arriving progressively earlier in the calendar year. This does not mean that every Spring starts sooner than the year before, but that an overall trend has been observed. For example, a survey of leafing, flowering and fruiting records from 1971-2000 for 542 plant species in 21 European Union countries showed advanced timing for 78% of the plants. According to other sources, “Spring events, such as blooming, frog breeding and migrant bird arrivals, have advanced 2.3 days per decade.” Winter snow cover duration—as measured from Fall to Spring—has decreased throughout the Northern Hemisphere since 1978. The earlier the snow melts, the less water is available during the hot summer, which affects a wide range of plants, animals and other life.
Winters have been warming. For example, the average February maximum temperature in the US rose by 0.3 F per decade from 1895-2016. This general rise in the “floor” has been accompanied by an increase in “extreme” events, such as “false Springs” when temperatures warm up enough to trigger life cycle stages in a variety of species. When more “normal” weather arrives later—or another extreme event follows, but this time on the cold side—a plant can be injured or even killed. A common example is when a hot spell causes fruit trees to flower, and then a frost—even just a “normal” one—zaps the flowers, thereby taking out that year’s harvest.
When we were farmers, we experienced how extreme events affect crops. In the Spring of 2013, periods of warmer-than-average weather alternated with periods of colder-than-average weather a few times, and the transitions between them were quick, as in 36 hours. Spring greens thriving in “normal” cool temperatures would go to flower prematurely when the temperature rapidly heated up. Then, warm weather crops would stall out when the temps fell. Annual vegetable plants don’t do well with such erratic conditions and we watched helplessly as our failure rate climbed.
Nicole has observed the effects of season creep and extreme events on wild plants. In one example, in the spring of 2017, she took a camping trip across the state of Nevada with her aunties, one of whom knew the area well from over 30 years of time spent in the area tending and harvesting traditional Native American food plants. The three of them visited lower elevation patches of these native plants and observed high densities of a Biscuit Root known as Rabbit Gut (Cymopterus sp.) in foothill niches against the mountains. They saw many plants, possibly due to high rainfall the year before, but no flowering although it was the season. They mused that perhaps the plants were resting this year and would more energetically seed the next. But in 2018, when the two of them visited the same patches at the same time, they found very few plants at all, across the entire state. They wondered if the plants had broken dormancy earlier, during the false Spring in February of that year, only to be sent back to sleep by the cold weather that followed. These Biscuit Roots, although hardy and stout perennials, can only live through a certain number of aberrant events. Too many seasons of jagged temperature shifts will make their survival unlikely as the climate continues to change, in their present habitat.
For each plant species—wild or domesticated—a particular range of environmental conditions supports optimal growth and reproduction, and when these conditions are not met, all stages of plant life-cycles can be affected: germination, flowering, breaking dormancy, etc. The suffering of the plants manifests in variety of ways such as stunted growth, lower seed production, and weaker resistance to disease. In the case of human food crops, lower nutritional value can be an outcome. Conditions far enough outside the range of optimal are lethal, and the species will die off in certain locations.
Other species, however, will be well-suited to the new conditions, and will thrive as openings are made. Meanwhile, the original plants themselves might well have migrated to new areas, themselves, filling new openings there. This is a form of natural succession that has happened innumerable times in the planet’s history. The most recent globally-scaled example took place at the end of the last period of glaciation, about 11,700 years ago.
We are likely already seeing such climate-induced plant succession now. It has been observed that during the past twenty five years, plant and animal ranges have been shifting towards the poles at a rate of about six kilometers per decade.
However, this age-old, tried-and-true process is being interrupted in cases where a species is labeled “invasive” and is then exterminated by humans.
Climate change demands that we fundamentally alter our approach to relating with the rest of nature. A prerequisite would be to use way less, and take only what is needed. Continued degradation by development and expanding resource extraction is the result of what we could call an “invasive land ethic” that insists that land must be dominated. Changing this attitude is essential.
Precise predictions for the future are difficult, and many scenarios are being studied. We can say with certainty that our present trajectory is anything but stable. Under midrange global-warming scenarios, scientists at Leeds University in England found that by 2050, 15 to 37 percent of terrestrial species (plant and animal) will be “committed to extinction” in their current ranges. This points to a practical difficulty in how to proceed with conservation and restoration plans. Everyone will be needing to adapt, and whether species can adapt in place or will need to migrate and how far are hard to know.
As Alejandro E. Comacho put it, in reference to policy reform, it makes less sense to be “dedicating substantial resources to preserving and restoring a particular biological unit because it existed in one point in time if climatic conditions may make the landscape inhospitable to that unit…. Similarly, what is the ethical or scientific justification for prohibiting or removing any organism simply because it never existed in a particular location, especially if that organism is now well-matched.”
What hasn’t been widely acknowledged yet is that restoration of previous, pre-global warming plant communities is no longer possible; conditions are already too different and the rate of change is increasing too fast.
As such, indulging in “invasion biology” at this point in history is a form of climate change denialism.
In the past, climate-induced plant succession has been a fairly gradual process, taking centuries or millennia. However, in our era of increasingly rapid climate change, fewer and fewer species of plants will be able to successfully migrate. If they are to survive, they will require assistance.
Assisted migration has been finding growing support these days. In 2009, the United Nations Environment Program (UNEP) stated the possibility of necessary large-scale translocations, and that “the conservation community needs to move beyond the preservation or restoration of species and ecosystems in place as the correct approach.” The US Fish and Wildlife Service followed suit in calling for policy revisions of what constitutes native, invasive or exotic species, as well as new policies such as assisted migration to support adaptive responses to climate change. It is has become apparent within the domain of large scale policy that the complete dualism of the good native and the bad exotic is neither accurate or helpful at this point.
There are protected niches within habitats, or new habitats, that will provide conditions that these plants could have a chance to thrive in. A north slope of a mountain may buffer against early dormancy breaking. A higher elevation may provide the temperature relief needed for them to grow. Arguably, birds and other animals are already participating in this assisted migration, as they are often the agents moving plants into new areas.
Seed vaults are created, with controlled climates in order to stockpile seeds for future restoration, yet conservationists balk at the idea of planting living seed banks outside of current ranges, where plants can be adapting on their own to respond to changes. How would the cold-stored seeds, with their genetic variability frozen in time, be better suited to a new environment than plant populations that have adapted in real time to emerging circumstances and have been passing that information along for successive generations?
Assisted migration is not a new thing. It has been the way of human-plant relations for many many millennia, since well before the adoption of agriculture. It is time for us to rediscover this part of our essential connection to nature.
The invention of “nativeness”
Describing plants as “native” was first proposed by British botanist Hewett Cottrell (H. C.) Wallace in the mid-19thcentury. His reasoning for the category was that local plants would show a reliable correlation with soil and climate. He stated that a native species was “apparently an aboriginal species; there being little or no reason for supposing it to have been introduced by human agency.” His definition included “naturalized” species who were “originally introduced by human agency [and] now exist in a wild state; some … continued by unintentional sowings … while several keep their acquired hold of the soil unaided, and often despite our efforts to dispossess them.”
In Nazi Germany, the conflict between native vs. non-native plants was put into the context of the larger war efforts. Writes journalist Andrew Cockburn:
“Nazism’s view of non-native plants was consistent with its view of non-native humans. ‘As with the fight against Bolshevism, in which our entire Occidental culture is at stake, so with the fight against this Mongolian invader, in which the beauty of our home forest is at stake,’ wrote a team of German biologists in 1942 regarding Impatiens parviflora, a small plant native to Asia.”
In reference to this conflation of biology and bigotry, biologist Stephen Jay Gould warned:
“When biologically based claims have such a range of political usages (however dubious, and however unfairly drawn some may be), it becomes particularly incumbent upon us to examine the scientific validity of the underlying arguments, if only to acquire weapons to guard against usages that properly inspire our ethical opposition (for if the biological bases are wrong, then we hold a direct weapon; and if they are right, then at least we understand the argument properly, and can accurately drive the wedge that always separates factual claims from ethical beliefs).
“Any argument for preferring native plants must rest upon some construction of evolutionary theory—a difficult proposition (as we shall see) because evolution is so widely misconstrued and, when properly understood, so difficult to utilize for the defense of intrinsic native superiority.”
The founding tome of invasion biology was written by Charles Elton in 1958. “The Ecology of Invasions by Animals and Plants” is not really an academic book, but rather a diatribe laden with war jargon. While suggesting that all human transportation of species is an affront to the geologic time scale (except for agriculture, of course), he also seemed to believe that all species movement since the break-up of Pangaea was invasive.
Elton’s tone clearly set natives as morally superior to aliens. His war cry opposes consequences such as “dislocation, unexpected consequences, an increase in the complexity of ecosystems already difficult enough to understand let alone control, and the piling up of new human difficulties.”
It is curious to note that in earlier publications, Elton had promoted the concept of ecological succession “steeped in the notions of changing habitats and dispersing organisms” with no mention of of invasion. But in the intervening time, during WWII, his job focused on the “immediate needs of protecting food from rabbits, rats, and house mice as part of national defence.” One can’t help but see the shift in perspective as mirroring both his personal and cultural experiences: nature went from an ever-changing flow of natural migrations to a static climax state suffering difficult-to-control invasions. Regardless of the reasons for his shift, his book set a bellicose tone that is still alive and well today.
The modern notion of “native” species excludes any “naturalized” species introduced by human agency, with a reference point for nativeness being, in the Western Hemisphere, 1492. There is a pointed separation imposed between “human introduction” and “natural dispersal.”
Darwin’s studies showed how individual birds and insects could carry dozens of seed species a number of miles, from a few to thousands. This mode of dispersal equals or dwarfs human plant exchanges. “The farthest known seed dispersal without the aid of humans is fifteen thousand miles. Dust storms can carry seeds, spores, and insects from the Sahara Desert to Texas, and ocean currents can carry seeds and spores across thousands of miles of open water to inhabit new islands and continents. Darwin once commented that he witnessed seeds within the soil of a tree root stump that had drifted across the ocean.” Are these dispersals to be ignored as valid migration? How does human agency delegitimize the flow thereafter? This ideal ecosystem model stems from a narrow interpretation of the processes of succession, of which we are inescapably a part.
Guilty until proven innocent
A major error in invasive biology is the use of the word, “invasive,” as a taxonomic attribute of particular species rather than as a description of an ecological interaction. That is, once a particular non-native plant is described as undesirable with any number of adjectives (noxious, weedy, nuisance, etc.) and is deemed “invasive,” that entire species ends up carrying the dreaded label, like a scarlet “I.”
This presumption hijacks the ability to clearly see interactions in a particular setting, and severely inhibits understanding about why a change is happening and how resident plants are actually responding. The “invasive species” label tells us that because that plant was bad over there (notwithstanding whether there was any credible evidence for the accusation) it will be bad over here. This is not good science.
Assessment of the place of non-native species in the environment has evolved to an unfortunate and unscientific state of “guilty until proven innocent.” A major criticism of invasion biology is that it starts from an assumed answer (non-native plants have bad effects), tests this hypothesis with no regard for other factors, and ends up relying on exaggerations of inconclusive data.
The assertion of ethical valuations that bind the field of invasive biology have led some ecologists to view it as a “pseudoscience” that has isolated itself from other ecological insights. The good native/bad non-native dichotomy relies on circular arguments that refuse to acknowledge conflicting data; assumptions are not adequately tested and limited findings are exaggerated in too many reported results.
To characterize any change at all as “harm” is to cling to an outdated idea of the environment as being settled and constant, a view that is not the consensus among ecologists. From its inception, the “field of invasion ecology has largely dissociated itself from other sub-disciplines of ecology, particularly succession ecology.” This has produced a narrow view that targets a few individual species as drivers of all disruption. Invasion is also claimed to be totally different from “colonization,” a recognized ecological process marked by a continual, natural occurrence of habitat succession. The fact that invasion and colonization have been explicitly linked is largely ignored and “is further evidence of the persistent isolation of invasion ecology.”
“Today, fewer and fewer ecologists believe nature is either stable or perfectible. Change is the norm, they say,” writes journalist, Fred Pearce. Since the beginning of Western thought on ecology, there has been discussion of many functional pathways. The idea of habitat succession began with the studies by Clements in the early 1900s. He promoted the idea of the environment as an organism, functioning as a whole due to a co-evolutionary process of interaction. During that same time period, Gleason talked about succession consisting of more spontaneous interactions creating habitat, focusing on the individual plants within the habitat organism, each functioning via their own relationships primarily. Somewhere along the way the idea of a rigid timeline of succession became popular, and the debate of the many pathways continues.
Ultimately, there are many types of relationships that mingle, creating habitats both from long term co-evolution and spontaneously kindred adaptations. In the mid 1980s evolutionary ecologist Dan Jenzen clarified the concept of “ecological fitting”, in which “a species does not have to evolve in a habitat in order to participate in the interactions in that habitat.” Within this theory, species may have developed certain defense traits as the result of co-evolution with certain predators, but that those traits also help the species “fit” into a new community without the same pressures. Co-evolution is deemed to occur when each species imposes evolutionary selection on the other, where everyone has their place. With “ecological fitting” species may find a niche in a new community without co-evolution.
Examples of fitting can be observed today. Says biologist, Dan Jantzen: “The complex interactions enacted by introduced species of animals and plants all over the tropics make it quite clear that a species does not have to evolve in a habitat in order to participate in the interactions in that habitat. Widespread species are not adapted to their habitats, they just are.”
Perhaps our ideas about succession are too narrow, limiting our ability to recognize it as it’s happening. There is an attachment to a particular set of species selected from recent history. But just because the actors change does not mean the process of succession is not still at play. It may be that it is more spontaneous in nature, with the familiar and exotic mixing and supporting mutual adaptation as we speak.
The long term, committed relationship of co-evolution is not the only path to intimacy. Proximity could be the catalyst for intimacy, not familiarity. “Perhaps finding an ecological niche is a bit like falling in love,” as Fed Pearce mused. This type of “ecological fitting” describes ecosystems as exhibiting a more fluid self-organization, with the formation of novel intimacies between previously unfamiliar species. An example would be the reality that one third of California’s native butterflies now depend on non native plants for their food. We could also be more fluid in our approach to stewarding resilience in the face of change.
The campaign against “invasive” species fails to accept “non-natives as valuable community members.” As a result, non native plants are not counted in biodiversity indices. The omission of them paints a picture of decreasing biodiversity, when in fact “the introduction of non-native species has almost always increased the number of species in a region.” There are a growing number of ecologists who are calling for biodiversity and sustainability assessments to capture more than just the presumed negative aspects of non-native species in order reflect the whole picture of change. Currently unaccounted for are contributions (increase in regional species richness, positive interactions with other species), and ecosystem services (i.e., provisioning, regulating, cultural and supporting).
“Novel ecosystems” is a term given to new species combinations within habitats. These ecosystems are “increasingly being recognized as maintaining critical ecosystem processes, such as productivity, carbon storage, and nutrient cycling.” It seems essential to include them, since non-native species in some regions and cities make up over half of all species. Their omission from measurements meant to provide insight creates a false narrative of how the environment is responding to change. The picture is biased towards seeing any change as degradation, instead of restorative in its own right.
“We need to understand Nature doesn’t make mistakes, that Earth is, at minimum, 3.5 billions years old, and that earth has been engaging in this process a lot longer than our species has existed…We need to understand that processes that no scientists understand are occurring on both very large and very small scales… So, when we see “invasive’ plants moving wholesale into new ecosystems, we need to ask in all humility, What are they doing? What is their purpose?”
For the most part, invasion biology is not interested in asking these questions, but only in building a case for demonization. That’s not good science. That’s the stuff that cults are made of.
No “wilderness” to restore
Agriculture, and the human dispersal thereof, is distinctly absent from these considerations of invasion, which presupposes a fundamental separation of natural processes and human activity. It’s as if we’ve created sacrifice zones in the valleys that produce our sustenance, where the same biases do not apply.
But the “wilderness” we struggle to restore here in North America is often comprised of untended remnants of past human cultures who significantly shaped their ecosystem homes, though from a place of direct connection rather than exploitation. This reality is routinely dismissed as irrelevant when it is acknowledged at all, which is not often, even though it arguably points to the way forward for the evolution of our own relationship with the planet. Instead we aim to recreate the past in the form of an idealized standard that never existed. Pearce describes this goal as “both impossible and an affront to nature, like trying to turn the world into a giant zoo.”
Indeed, the modern idea of “wilderness” is a new idea, and thus not something we can recreate. Many areas previously considered wilderness have turned out to be anthropogenic landscapes. In our hubris, we start from a place of human separation from “wilderness” to begin a process of intense management of it. To achieve the appearance of a pristine ideal, all traces of human agency must be erased, yet the dominating mentality remains in this erasure itself. This focus on appearances detracts from addressing underlying catalysts of degradation such as agriculture, resource extraction, and pollution, to which some species of plants (non-native and native alike) are attempting to adapt.
The first step in most restoration projects is to interrupt the start at succession which nature has offered. Will we seek to conserve one part at the expense of the whole, pulling and poisoning our way back to a managed “pristine?”
Changing our cultural mind frames
Perhaps the most essential disconnect in understanding ecosystem change is inherent in the predominant cultural mind frame. Anchored in the scientific rationale are particular cultural prejudices; for example, within “Western tradition there is a recognized hierarchy of beings, with, of course, the human being on top—the pinnacle of evolution, the darling of Creation—and the plants at the bottom.” This hierarchal view assumes the “lower” lifeforms are somehow less (or not at all) alive, and thus have no intelligence of their own. This is not a universal perception of life. Indigenous cultures around the world have a common belief about the agency of plants and animals as sentient beings, and often look to them as sources of wisdom to teach by example, and show the humans how to live on Earth as their “younger brothers of creation.”
When asked about their thoughts on invasive species, Anishnaabe tradition-bearers pointed to “invasive land-ethics” as being the real threat underlining the cause of the changes we see today. The “invasive land ethics” are rooted in the belief that land should be dominated, a belief imported with colonial settlement.From this perspective, environmental management practices such as the dredging, damming and channelizing of rivers are an affront, with their audacity to command and control natural processes and places. (Apparently this view extends to controlling the environmental resilience to such practices as well, as that resilience is expressed by non-native plant species.)
Kathy Leblanc, an Anishnaabe collaborator for ethnographic studies on the subject, suggested that non-native plants “may just be enacting their own migration stories.” In Australia, Aboriginal resistance to “invasive” eradication programs is tied to a belief “that the worth of a species lies in its ability to flourish in an environment, not in it claim to being an original inhabitant.”
Stewarding the land from the view point of enriching life (rather than trying to control it) is responsible for much of the biodiversity we have today. Research and stories of multi-generational use show that some of the most diverse ecosystems “were not untouched environments but the result of the last ‘cycle of abandonment’ by traditional users.” A huge example is the Amazon Rainforests.
Evidence of long-term interaction can be observed other places by learning to read the landscape from a perspective of interaction, not separation. Tribal stories contain detailed information of who, what, when and how the living world was utilized towards increased abundance and diversity. The denial that previous human interaction in fact helped shape the wilderness gives credence to the proposal to remove any plant species that arrived by our hand.
This is perhaps our dilemma: that we cannot see resilience—only misery. As Issac Yuen suggests: “Given a narrative borne out of the loss of pure wilderness, we can’t help but view the world and our actions within it through a lens of self-loathing and despair.”
For all the faith given to scientific understanding, there is little agreement on the claims of much of invasion biology. First, such claims are too often not actually supported by scientific data, but by repeated rhetoric alone. Another reason is that science aims to understand complex systems by dissection, assuming the outcome of interactions within an entire system based on isolated findings in isolated portions. The lab does not translate well to the field. A third reason is that science is not an unbiased inquiry when assumptions are a part of the hypothesis. That means other factors are not studied, and the aim is to prove what is expected.
Our understanding of ecosystem dynamics and the factors of resilience cannot not be known by science alone. As Robin Wall Kimmerer puts it so succinctly in her book, Braiding Sweetgrass: “Science as a way of knowing is too narrow for the task.”
We must do nothing less than address the fundamental ways in which we relate with nature and radically change them. The needless killing must stop.
Imagine for a moment that the term “invasive species” didn’t exist. Imagine that another current term was popular instead, one that is already used to designate plants who are the first to establish themselves in a newly disturbed area: “pioneer species.”
Imagine further that its synonyms were not “aliens” or “non-natives” but “explorers” and “frontier-species.”
Why, such plants would be celebrated for their patriotism! They would be called “brave” not “aggressive,” “ground-breaking” not “encroaching,” and “thriving” not “threatening.”
Now imagine the uphill battle you’d have trying to convince people that the “pioneers” were having negative effects and needed to be controlled; that, in fact, their heroes are villains. Imagine trying to attach the adjective “invasive” to “pioneer.” That would never fly (despite—or because of?—its historical accuracy in the case of human pioneers).
Your campaign would be fruitless and lonely. (And you’d know what it feels like to be an anti-imperialist in the USA!)
In our case, with this article, we are not seeking such a drastic shift, from one extreme to the other. Rather, we would like to see the discussion of new plants taken out of the realm of value judgments entirely and instead be based in reality-based observations, analysis and participation. Put simply, we are seeking to look clearly, reckon truthfully and act sensibly.
But maybe this is wishing for an even more radical shift. Perhaps trying to convince people that good is evil or that evil is good is less arduous than trying to convince them to have a conversation that isn’t about either one.
“Your whole life is divided into opposites – virtue and non-virtue, right and wrong – because you never meet life completely but always with this reaction, with this background of division. You have created this background; you have crippled your mind with these ideas…”
In other times and places, we believe, humans were not so crippled. Not that there wasn’t danger or conflict, but—seen without the distorting lens of dualism—those are merely conditions of living that come and go like conditions of weather.
Just as rain, wind and sunshine are not good or evil, neither is any particular species of plant. In certain situations, as measured by certain criteria, we might find certain plants to be helpful or harmful. But all that certainty is only in our mind.
For example: If we are hungry and find a blackberry bush full of ripe fruit, we might love the plant and call it a friend. If we are thirsty and are blocked from a riverbank by the same bush’s thorny vines, we might hate it and call it an enemy. In both cases, the emotion and the name-calling are ours, and ours alone. The blackberry bush did not change. To insist that our characterization of the plant in either of these discrete instances is equivalent to describing the intrinsic nature of the species as a whole is delusional.
Yet, this, in a nutshell, is the assertion being made with the application of the loaded word, “invasive” to an entire plant species. A certainty has been proclaimed.
Returning to the blackberry, let’s say that we encountered it first when we were thirsty and acted on our certainty of its evil nature in that moment to hack it down to the ground. After having a drink at the river and taking a nap from our labors, we later wake up hungry. Making our way back up the bank, we don’t even notice the smashed berries in the dirt as we step over the chopped canes. After all, that plant was no good, didn’t belong there, and the world is a better place with it gone. Can’t wait to track it down and kill it everywhere else we find it.
Such behavior saddens and enrages us. We see no maturity or intelligence in such attitudes and actions.
Imagine a world not divided into “good” and “evil.” A world without antagonism, hostility and competition. A world, instead, of openness, respect and cooperation.
Imagine that world, if you can.
 Thompson, Ken. Where Do Camels Belong? The Story and Science of Invasive Species (London: Profile Books, February 2014), p.82.5.
 Elton, Charles S. The Ecology of Invasions by Plants and Animals (Chapman and Hall: London, 1958). p. 57.
 Scott, Timothy Lee. Invasive Plant Medicine: The Ecological Benefits and Healing Abilities of Invasives (Healing Arts Press: Rochester, VT, 2010), p. 73.
 Pearce, Fred. The New Wild: Why Invasive Species will be Nature’s Salvation (Beacon Press: Boston, MA, 2015), E-pub E-pub p. 180.
 Pearce, p. 366
 Pearce, p. 34.
 Pearce, p. 15.
 Berkes, Fikret. Sacred Ecology, 2nd edition (Taylor and Francis: New York NY, 1999). p. 236.
 Kimmerer, Robin Wall. Braiding Sweetgrass (Milkweed Editions: Canada, 2013), p. 38.
 Kimmerer, p. 38.
 Kimmerer, p. 103.