For a few years now, I have invested time and energy into cultivating native plants and removing invasive, non-native ones – as a paid worker, an unpaid volunteer and a recreational gardener. My reason for this work is that native plants are beneficial to the local landscape but threatened by invasive plants, a notion well-supported by scientific research and further endorsed by many governmental initiatives. While I sense that the American public is becoming increasingly aware of the economic and ecological threats that some high-profile species pose, I’ve encountered various reactions to how such species are removed, especially when pesticides are involved. I want to better understand the complexities of invasion ecology so that I can advocate for smart natural resource management. But I must admit, I harbor a certain uneasiness about the dichotomy of “native vs. non-native” that is so prevalent in invasive species discourse, and believe some reflection is in order – Julia
Early autumn in Michigan is a time to enjoy the blooming of asters, the turning colors of broadleaves, the harvesting of apples, the migration of neotropical birds, and the cooling weather. It is also the most effective time to chemically control the invasive common reed, Phragmites australis, referred to often as Phragmites.
There are three lineages of Phragmites australis, one that has been in the U.S. long before Europeans came, one that is also likely native, and one that was transported from Europe by humans. Here in the U.S., this human-introduced lineage establishes dense monocultures, in part because it lacks significant herbivores or pathogens to curb its growth, outcompeting native vegetation (including its native cousin!) and altering hydrological cycles (Great Lakes Phragmites Collaborative). Several governmental and non-profit agencies have partnered with volunteers and ecological restoration businesses to remove invasive Phragmites and other pernicious exotic weeds. Even people who claim to love plants are spraying pesticides to kill it!
Phragmites may trigger emotional reactions in some, but not all, people. I have met folks who feel stress or anger when they see it growing on a roadside or popping up in a wetland – “there goes the neighborhood.” Outside of conservation circles, I have encountered a neutral or disinterested attitude towards the reed. Further, I have also witnessed people admiring its tall stature, its cone-shaped tufts of seed, the thick privacy wall it builds, or its wild dances in the wind. Before we attempt to understand these three, generalized reactions, I’d like to define what makes a species native or non-native, and clarify some ambiguities.
The Natural Resource Conservation Service (NRCS) defines native plants as “part of the balance of nature that has developed over hundreds of thousands of years in a particular region or ecosystem,” emphasizing the importance of biogeography. Anything else is non-native. If a plant has evolved to naturally occur and propagate in a Midwestern tallgrass prairie, but it is planted by a human in mesic flatwood forest in New England where it is not known to be found, then it is non-native to that mesic flatwood and, in fact, can be considered ‘translocated.’ If that tallgrass prairie species were transported by a human across a continent, it would be considered ‘exotic’ in its new home.
Non-native plants may struggle to establish in foreign ecosystems, not only because they may not be suited for local conditions, but they may be killed off by random events. So those that do establish populations would be considered ‘naturalized’ according to the NRCS – or, non-native plants that can reproduce and survive in new areas independent of human cultivation. Some of these non-native, naturalized plants can become ‘invasive,’ outcompeting native plants, upsetting ecosystems, and creating monocultures. If they are upsetting enough to damage human property or a pose a threat to the environment, they may legally be considered ‘noxious weeds.’
Both native and non-native plants can be labeled weeds. Certain native plants are known to be aggressive or opportunistic, quickly establishing after a disturbance, but ecological factors like plant competition, succession (and subsequent changes in light availability and microclimate), wildfire, herbivory will keep that plant in check. Not only are invasive plants less inhibited by competition from other plants, they lack herbivores in their new home. That is because, as Douglas Tallamy explains in the book Bringing Nature Home, most insects are highly specialized in which species of plants they eat. Furthermore, if invasive plants outcompete the native plants that local insects rely on, there will be less food for them, which means fewer insects, which means fewer birds, etc. Not only will this disrupt human pleasure of birdwatching, it should certainly spark thousands of unforeseen consequences throughout Earth’s intricately linked ecosystems.
Therefore, I will use the term ‘invasive’ for strictly non-native plants. In fact, Executive Order 13112 (released by President Clinton in 1999 to establish the National Invasive Species Council) defines invasive species as “alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health.” One word – alien – does not sit well with me in the current political context of xenophobia and wall-building. But remember how I said invasive species can trigger emotional reactions? Let’s revisit the three I most often encounter.
The first, an angry or stressful reaction to invasive species, may be due in part to knowledge of the its effects on local ecosystems. I think it may also be fueled by some of the discourse surrounding non-native plants – aliens, invaders, etc. – that are purposefully emotional in order to inspire action. Susanna Lidström and Simon West thought so, too, and write in a blog post “the concept of invasive alien species steers our thoughts towards countless science fiction films about space invaders – where characters are easily identified in terms of “good versus evil,” “native versus foreign,” “belonging and not-belonging.”
But why the dichotomy? Lidström and West draw parallels between the language used for invasive species control in South Africa and its post-apartheid xenophobia, or the discourse in Europe and its immigration booms and border insecurity. People who work in conservation see Phragmites choking out a wetland and feel loss – a place they know/love is literally being invaded. But ecology is too complex to be effectively managed by such dichotomous perspectives. Lidström and West argue, “the concept of invasive alien species simply does not help us understand how nature works, but instead promotes aggressive ways of relating to our environment, and siphons resources that might be better spent elsewhere,” suggesting that larger, more encompassing issues like climate change are making “little headway” and thus could benefit from time and energy of the natural resources community.
The dramatic language of alien invaders only works on some people. The second emotional reaction I’ve encountered – disinterest or a neutral attitude –may be due to what some authors have called “plant blindness.” As humans become increasingly disconnected with our natural environment, it’s no surprise few people have noticed its replacement of other species. The invasive subspecies of Phragmites was introduced in the East Coast in the early 19th century, so it’s been here long enough for folks to get used to it.
The third reaction – appreciation – is different than plant blindness, because here someone is actively appreciating a plant for its unique physical traits. And if it is true that Phragmites will be impossible to eradicate – that it is here to stay as part of a novel ecosystem – then it is only natural that humans may form an appreciation of it as part of a broader effort to connect with our environment (as pure or impure as it may be). Research suggests (see here and here, for example) that greenery and natural spaces can have positive impacts on human health, but it rarely distinguishes which species. Invasive plants are still better than no plants at all, right? To answer that requires a thorough cost-benefit analysis of all damages, benefits, and costs to control that are associated with a given invasive species. It will also be informed by time, as we watch the effects of European exploitation and stewardship play out and hopefully learn from our mistakes.
Because, like many environmental problems, invasive species can be understood as a product of settler colonialism and globalization. Europeans came to North America, stole land from the indigenous people, and exploited the landscape for its natural resources, causing significant ecological change and degradation (for example: logging in Michigan post-European settlement causing shifts in forest composition).Then, as more and more settlers came, and global trade expanded, non-native plants came too. Mack and Erneberg (2002) studied introductions before 1900s by Europeans through planting culinary and medicinal herbs like dandelion (Taraxacum officinale), ornamentals like multi-flora rose (Rosa multiflora Thunb.) and buckthorn (Rhamnus cathartica L.), and accidentally introducing them through seed contamination like Achillea millefolium, Chenopordium album, Cirsium arvense, etc. As the United States’ economy continued to globalize, these introductions increased. Mack and Erneberg (2002) mention one study of invasive plants in Illinois, with 163 species added between 1922 and 1955, and 209 additional introduced between 1956 and 1978. As the Europeans colonized, so did their plants. As a product of European settlers, I am part of a novel human ecosystem.
A critically important, but often overlooked, set of perspectives that Midwesterners of European descent (like me) can learn from is that of the Anishinaabe. Reo and Ogden (2018) interviewed the Sault Ste Marie Tribe of Chippewa Indians and the Bay Mills Indian Community (which represents a wide range of values and perspectives) about their experience with invasive plants. From these discussions, the authors pulled the following three themes informed by Anishinaabe teachings. One: “recognizing all plants and animals as persons who assemble in ‘nations.’” Two: “it is the responsibility of humans to determine the reason why new plants or animals have arrived in their territories, and actively determine the nature of novel human-animal or human-plant relationships.” Three: indigenous folks “reframed problems of environmental change as related to the introduction of a Euro-American land ethic…culpability lies in “invasive” ideologies rather than the fault of specific animals or plants” (Reo and Ogden, 2018). Yeah, wow.
The Sault Ste Marie tribe members interviewed by Reo and Ogden (2018) expanded on invasive ideologies to include “Euro-American property ownership regimes, ‘command and control’ forms of environmental management, and a worldview predicated on the separation of people from nature.” Settler colonialism and globalization have promoted the invasive species problem, yes, but more importantly, they have significantly changed humanity’s relationship to land. Is there hope for shifting towards a more sustainable, holistic relationship?
Let’s revisit the second theme from Reo and Ogden (2018), in which the Anishinaabe teach that humans must find uses and purposes for newly arriving plants or animals. If an invasive plant is here to stay, can we use it? As Reo and Ogden (2018) point out, the Anishinaabe have traditionally used the native broad-leaved cattail (Typha latifolia) for food, so perhaps the introduced narrow-leaved cattail (Typha angustifolia) that is taking over wetlands and hybridizing with T. latifolia will prove nourishing, too. According to the NRCS, the endemic lineage of Phragmites has been used by Native Americans for “arrow shafts, musical instruments, ceremonial objects, cigarettes, and woven mats,” while Europeans have used common reed for thatching, so why can’t the introduced lineage also be useful in Michigan?
Many folks are putting this Anishinaabe teaching into practice. The Strawbale Studio has been harvesting Phragmites in Oxford, Michigan to thatch roofs. Artist Megan Heeres has been using the pulp of Japanese knotweed, honeysuckle, and other invasive to make paper and build community through the Invasive Paper Project, while another group of artists called the Detroit Tree of Heaven Woodshop has been using the wood from Ailanthus altissima growing in alleys and vacant lots to build sculptures and furniture.
Robin Wall Kimmerer, in the book Braiding Sweetgrass, mentions one example of an immigrant that became a good neighbor – the common plantain (Plantago major). Plantain was brought to Turtle Island (North America) by Europeans and gradually embraced by Native people for its nourishing and healing properties. Kimmerer writes, “our immigrant plant teachers offer a lot of different models for how not to make themsleves welcome on a new continent. Garlic mustard poisons the soil so that native species will die….but Plantain is not like that. Its strategy is to be useful, to fit into small places, to coexist with others around the dooryard, to heal wounds.” Kimmerer expounds that people like me (descendants of immigrants/settlers in this colonized land) can learn from Plantain to become naturalized – “to know that your ancestors lie in the ground…to take care of the land as if our lives and the lives of all our relatives depend on it.”
I hope to learn from these teachings and continue to form a nuanced connection with my human-altered environment. For me, the delicate, popping purple blooms of European chicory (Cichorium intybus) in unmowed, vacant lots each July is a special indicator that it is mid-summer in Detroit. The introduced Bradford pear (Pyrus calleryana) blossoms in spring are aesthetically beautiful in places where few other trees exist, as are the native red maple (Acer rubrum) flowers that emerge in spring across many mesic forests of Michigan. I still plant asters, milkweeds, and goldenrods to attract native pollinators, and try to control the spread of mulberry and tree-of-heaven in the alleys. I resent that non-native buckthorn (Rhamnus spp.) and honeysuckle (Lonicera spp.) now dominate the understories of many parks, and hope all the money spent on removing them actually restores biodiversity across the landscape.
It is late autumn now and I am standing at the top of a small rise overlooking a wet field. There is a Phragmites patch in the distance, its leaves mostly yellow – it is too late in the growing season to chemically treat. Besides, I am mostly there to work on the seeding of native plants. This field was a farm that is being restored to a wetland and prairie. The land has been disturbed by humans many times over. I have a lot of questions and things to learn. I sense true restoration may not be possible…but a transformation to healthier relationship to land will require deep listening and inclusive, adaptive management.