Defining Nature in a Globalizing World

Mark Davis
DeWitt Wallace Professor of Biology  
Macalester College

Mark is the DeWitt Wallace Professor of Biology at Macalester College, where he has been a faculty member since 1981.  His research, writings, and presentations focus on the ecology of introduced species and the field of invasion biology. Mark is the author of Invasion Biology, and numerous articles in journals such as Nature, Bioscience and the Journal of Ecology.

Comments 35

  1. Thank you Professor Davis for helping us open the Feral conference with such an exciting and cogent presentation!

    I’m personally thrilled to hear these arguments being articulated from a biological and ecological perspective and to think about the parallels between these debates in different scientific and humanistic contexts. At this stage, I’d like to invite questions and comments from conference ‘attendees’ and other participants in response to this presentation, but also, to get the ball rolling, I have a question of my own: you suggest that after the end of the conservation/restoration paradigm, we will need to assess the organisms on their environmental impact, rather than their origin: could you please give us a sense of how that impact might be assessed in an ecological context?

    Once you’ve watched Professor Davis’ presentation, I would also encourage everyone to check out some of the other panels that are active this week.

  2. Hi Mark,

    I agree with Nick. Fantastic presentation. So clear and concise.

    I share your – may I say – optimism that invasion biology is a passing fad. I also agree that nativism leads to poor science because it muddles the distinction between empirical and ethical forms of knowledge, and in the process does justice to neither.

    I also have a question. I note your use of the term “immigrant” instead of “introduced”. I have been using the language of migration as well in the past few years (immigrant, emigrant, migrant, even refugee at times) to do away with invasion biology’s militaristic jargon. There are some clear benefits to this group of terms. However, since most of these “immigrants” have been in their “novel” ecosystems for hundreds of generations, and since no one but some humans are aware that they are “not from around here”, could these terms act to reinforce the dichotomy we’re trying to get rid of.

    BTW – and finally – in Israel the prickly pear is a symbol of human nativity for both Jewish Israelis and Palestinians, even though it originated from central America and was probably brought to Israel/Palestine 50-200 years ago (I don’t remember the number exactly).

    Best wishes, Arian

    1. Hello Arian, great to hear from you. Actually, the use of the word ‘immigrant’ in my presentation wasn’t my idea. It was simply in the definition of nativism that I pulled off of google. Merriam-Websterj similarly used the word ‘immigrant’ in their definition. I do agree that for species that have been in place for hundreds of generations using words like ‘immigrant’ doesn’t make much sense and just maintains the dubious dichotomy. –Mark

  3. Hi Mark
    Yes, awesome presentation, thank you. It was really interesting and so well structured and explained. I’ve not heard of the idea of ecological novelty but have long wondered about the plant racism I have encountered. I suppose the challenge is that this new paradigm is not interpreted as ‘anything goes’, or perhaps that is what you are recommending?
    Thanks, Ronlyn

    1. Hello Ronlyn, thanks for your kind words. Ecological novelty definitely does not mean ‘anything goes’. Without question we are going to have to adapt to some of the ecological novelty. But, the specific objectives for particular sites will guide the land managers, e.g., manage for biodiversity, or pollinator-friendly plants, or to reduce the effects of wave action during hurricanes. Those objectives will emerge from society’s values and wishes.–Mark

      1. Well said Mark,

        I appreciate this idea that Ecological Novelty does not mean “anything goes”. This is truly fraught philosophical territory that often prioritizes the needs of humans, but I appreciate how your presentation made efforts to discuss the complexity of what is “natural”. Often, we fight against totally natural forces to reimpose what we consider to be the native balance, when perhaps this new ecological paradigm would be more beneficial?

  4. Hi Mark,

    That was a fascinating presentation. Thank you.

    I am very interested in what you were saying about the honey bee when looked at in conjunction with food security. Currently there are discussions around the danger to bees from insecticide use, together with statements about “if all the bees died humans would die of starvation” and other comments like that found in grey literature.

    I did not realise or had not thought through that honey bees, upon which we depend, are not native to many areas they are now found. They are only there because human activity brought them in and we rely on them. It is then not surprising that continued human activity threatens their tenuous grip on their new environment and more fool us for relying on them so heavily.

    As an aside my father used to shoot the hedge sparrows that ate the bread we threw out to the ‘native‘, but pretty, birds. Actually, the birds he thought of as native appear to have been imported around the 1800’s!!. He was a good shot and eventually the pretty birds adapted to the shots and didn’t fly away. We had few sparrows after that.


    1. Hello Rachel, thanks for your comments. You may be right that honeybees are particularly susceptible to human activities in areas where they were introduced. Unfortunately, the fate of many native bees is not too bright either. No question that we will be in dire trouble if our pollinators crash.–Mark

  5. Wow, what an interesting perspective, and something I had not really thought of before. The nativism paradigm is one of which I am very familiar, but the ideas of ecological novelty make a lot of sense, assuming the non-natives are not invasive species upsetting the ecosystems….is that your assumption?
    Thank you.

    1. Meaning that the biodiversity is negatively affected. E.g. invasive/immigrant/introduced non-native plant vines smothering native flora…

    2. Hi Vicktoria, I’m glad my presentation stimulated some thought for you. What do you mean by ‘upsetting’ the ecosystems? The term ‘upsetting’ is one of those value-laden terms that can cause confusion. The upsetting you are referring to is from a human perspective. For other organisms, the ecosystem changes may be beneficial. Like any species, introduced non-native species will affect ecosystem composition and dynamics. This would constitute ecosystem change. Whether that change is regarded as harm (or upsetting) or not is another issue, one determined by one’s value system.–Mark

  6. Thanks for your presentation. The challenges for ecologists or perhaps us all is to decide what is it that we need to do to retain biodiversity in our local spaces. I too would like to see a move away from the war on weeds/war on pests analogies but also fear loss of whole species if unbalanced ecosystems are left to their own devices. How do we manage our wild spaces? Which immigrants are tipping the scales and need active management. Which can or should be eradicated and which can we manage alongside. The context is different for each spaces and dependent on presence of species threatened with extinction. I love the idea of novel ecosystems but there is a place for preservation of unique species. So much rapid change, so much unpredictability. How do we build resilience?

    1. Hello Marian, you pose several good questions. Adopting the ecological novelty paradigm certainly does not mean that ecosystems should be left to their own devices. There is no easy answer to your question regarding how to manage our wild (or not wild) spaces. There is no ecological or divine imperative to guide us. It is up to us to decide how we want to manage the environment, which will emerge from our value systems. Do we want to manage for productivity, biodiversity, to prevent erosion, to protect a particular endangered or unique species? Our objectives will vary from site to site and ultimately will be decided in the public square. What does society value?–Mark

  7. Hello Arian, great to hear from you. Actually, the use of the word ‘immigrant’ in my presentation wasn’t my idea. It was simply in the definition of nativism that I pulled off of google. Merriam-Websterj similarly used the word ‘immigrant’ in their definition. I do agree that for species that have been in place for hundreds of generations using words like ‘immigrant’ doesn’t make much sense and just maintains the dubious dichotomy. –Mark

  8. Hi Mark and others,
    This was a wonderful keynote to introduce the underlying theme we will be discussing in the following weeks. As an anthropologist, ecological novelty is a shift in perspective when visualizing human-environmental relationships and I very much enjoyed it.

    My experience with ‘native’ and ‘non-native’ species is in relation to traditional ecological knowledge (TEK) of First Nations. Environmental extraction and degradation occurs within Treaty land, and the reforestation process typically replants ‘non-native’ species only (due to cost), species that First Nations (at this time) have no use for in traditional practices. That being said, your presentation today seems to focus more around city or urban ecologies where species are ‘introduced’ through means of transportation. What are your thoughts on ecological novelty in the bush? Do you see differences and/or similarities in novel ecosystems constructed by extractive industries and that of general transportation?

    Thank you

    1. Hello Abigael, good questions. Ecological novelty definitely applies to wild places as well as to urban and other populated and managed areas (e.g., farmlands). You are right that the communities created following mining and other extractive industries are often ecologically novel. With planning, and if native species can accomplish the objectives of the restoration, native species can be used instead of nonnative species. Even then, though, there is still likely to be some forms of ecological novelty, perhaps not so much in plant/tree species composition but in the soil microbiota and nutrient cycling.–Mark

  9. Thanks very much for your presentation; I wonder if the idea of ” ecological novelty ” is taken into account in the framework of the Convention on biological Diversity and its Aichi target 9: “By 2020, invasive alien species and pathways are identified and prioritized, priority species are controlled or eradicated and measures are in place to manage pathways to prevent their introduction and establishment” and in the recommendations on this subject to be discussed in the next conference of the Parties (COP-14) ( 17 – 29 November 201). You can see the Recommendation 22/8 at : ( .

    Thank you,


    1. Hello Rosa, No, ecological novelty was not mentioned. Perhaps not surprising though. The focus of 22/8 was mostly on the transport of organisms, rather than on ecosystems in which new species have established themselves.–Mark

  10. Hi Mark,

    Thanks for your insightful presentation, great way to begin the conference. I see from your replies to others that the language of ‘immigrants’ and ‘natives’ comes about by the constraints of the ecological paradigms which determine plant origins in narrow ways. I was wondering though in a settler colonial context how ecological novelty might also be a value-laden term in that it can displace a focus on human events (such as colonisation) that create profound ecological disturbances. In Australia, there is a bit of revival of bush tucker or native tucker as a way of valorising Indigenist knowledges and land management which I don’t think fits your definitions of restoration as nativist. Does this resonate in a US context?


    1. Hello Holly, I must admit I had to look up ‘bush tucker’ 🙂 . Ecological novelty doesn’t necessarily eliminate the distinction between native and introduced species. It just doesn’t use this distinction as the starting point for management. Interestingly and ironically those who passionately advocate a nativist stance are usually immigrants or descendants of immigrants themselves. I agree that the use of and preference for native plants by indigenous peoples is not the type of nativism I was referring to. This sort of nativism (the one used by indigenous peoples) is usually not accompanied by the highly normative and inflammatory language used by invasion biologists to describe introduced species.–Mark

  11. Hi Mark,

    Thanks for your lucid talk. I remember how relieved I was when your article came out in Nature in 2011 that finally biologists were coming to acknowledge how value-laden their management decisions are. Over the years, I have been fascinated with the biopolitics of conservation – how decisions over the life and death of nonhuman animal species are being made on a daily basis.

    I have a few follow up questions: First, I am wondering how you feel about human editing and modification of individuals and of entire species (via CRISPR and gene drives, for example). Would you call such altered populations “novel” and Is this also a decision that you would like to leave with the public? Take corals for example: there is a current debate within the coral scientists’ community whether it would be desirable to breed super corals who would be more resilient to the warming temps and rising acidity of the oceans. What would be the status of such corals, in your view, and what do you think about such and other, even more radical, suggestions for genetic modification?

    Second and relatedly, when you say that the decisions over what kind of nature we would like to see and manage is a democratic one, what exactly do you mean? I wonder whether democratization is a legitimizing process that in fact reifies certain power relations, especially of those structurally less empowered groups. Also, this decision-making process sounds very human-focused. Would nonhumans have standing in deciding about their future? What would be the processes of such decision making and what kind of institutions would you envision governing such processes?

    And finally: would you suggest norms and constitutions for governing such democratic decision-making processes, or would it be acceptable that the public decide anything it wants about how to manage species, for example that it wants to go completely “native,” e.g. take a “humans-first” approach and eliminate all the rest? In other words, would you install into the system limitations as to what humans can decide in this context, or would you leave that decision, too, in the hands of the “public”?

    Thanks again,

    1. Hello Irus, I would consider species modified by CRISPR to be part of ecological novelty. Personally, I am hesitant to view CRISPR and gene drives as a panacea. One of things we learn from ecology is that one can almost never do just one thing by intervening. There will be other effects as well, often ones we didn’t anticipate. Regarding the decision-making process, I didn’t mean that there would be something like a public vote. Rather, existing agencies, e.g., departments of natural resources, would still make decisions regarding management objectives, BUT only after considerable effort to solicit public views of the proposed project. Too often I think the “experts” make the decisions based on their own value system without having sought public input. It would be very difficult to install system limitations that would prevent the public from choosing extreme objectives, since the public could simply change the limitations. Fortunately, in an open society, there are usually diverse perspectives, which would prevent the choosing of extreme objectives. Also, perspectives from outside the country can serve as advocates for less extreme objectives. For example, due to considerable pressure from inside and outside the country China just backed off its plan to allow the import and sale of rhino horns and tiger parts.–Mark

  12. Mark–One more comment regarding your presentation of restoration: it seems worthwhile to mention that in some areas of biology, traditional restoration approaches are being replaced by restoration approaches that tend toward the novel ecosystem perspective you outlined. See for example Madeleine van Oppen et al.’s 2017 publication “Shifting Paradigms in Restoration of the World’s Coral Reefs,” which calls for the application of “intervention ecology,” originally proposed for terrestrial systems, for coral reef management. Buki Rinkevich also documents the changing paradigms in coral reef restoration.

    I would like to finally thank the organizers of this conference for putting together this wonderful opportunity for near carbon-neutral interaction.

    1. excellent example, Irus. This illustrates how restoration ecology is becoming a more future-oriented effort rather than a past-oriented effort.–Mark

  13. Thankyou- Thought provoking for me,especially as we have just installed an outdoor learning environment at our local school. It consists mainly of NZ native plants and yet we put aside a small separate area to encourage bees with bright flowered immigrant plants . I have also wondered about restorative ecology when the local council insisted we cut down very large pines over 100 years old when planting out a wetland . The huge pines didn’t cause any ecological damage, they were on a hill and a haven for birds . Seems we are selective when considering the past .

  14. Hi Mark,

    thanks for the interesting presentation. My problem with the definition of invasive species is that relies on a human-nature dichotomy, as the origin of species is evaluated against human action (facilitation of movement), thus we have a pre-human and post-human location of species. But species are always in the move (it is a problem of time scale), and also how can we evaluate the human facilitation of species movement when human modification of the environment is so widespread. For example, a species movement because of suitable habitat displacement by climate change, it is probably not considered a biological invasion. I shared with you the interest in the novel ecosystems perspective, however, I have some concerns. Is “novel” also depending on an atemporal ecology? In other words, if ecosystems have an history of past changes, are not all present ecosystems novel? Is the human being a defining factor in novelty in this perspective?


    1. Hello Robert, Actually I’ve had the same reservations about the term ‘novel’ since ecological novelty was proposed by Richard Hobbs in 2006. You are right that ecosystems are always changing. But, the horse is out of the barn now and ‘ecological novelty’ is the phrase that is used now. I also agree with your assessment of the term ‘invasive species’. The dichotomous thinking is very forced.

  15. Hello Mark,

    That was an excellent presentation, and it touched on a lot of important points, especially the notion of how a particular species functions in an ecosystem being more important than it’s classification as “native” or “non-native”. This made my mind wander to a few plants in particular: Phragmites, Himalayan blackberry, and spotted knapweed.

    In the northeastern U.S., Phragmites is being aggressively sprayed because it is occupying wetland habitat formerly inhabited by cattails; in the northwestern U.S., Himalayan blackberry is the local bogeyman. Although it is unclear if Phragmites is native or non-native, it appears to be occupying degraded ecological niches. Himalayan blackberry is a known introduced species, but it also appears to be occupying ecological niches that are damaged, degraded, or modified in some way by human activity (i.e., it’s part of a “novel ecosystem”). In both cases, it appears to me (and I’m an archaeologist, not an ecologist, so this is a layman’s perspective) that human activity has constructed ideal niches for these plants which they subsequently occupy. And yet the plant gets blamed for “invading” this niche, instead of the humans for creating it in the first place. In spite of their flaws, both plants have proved useful to humans in some way: Phragmites (or a native variant) was useful to indigenous peoples in the past, and the blackberry is useful today, to those who wish to eat its fruit. Nevertheless, whether labeled “native” or otherwise, both are considered “noxious” for what I perceive to be economic reasons.

    The same goes for spotted knapweed. Where I live in Montana, knapweed is classified as a “noxious weed” because of its impact on grasses that are economically useful to cattle ranchers. However, honeybees seem to like it, and knapweed honey is plentiful and delicious. So this plant is not “noxious” from the perspective of the beekeeper. In the same way (and I touched on this in my presentation), plants like goosefoot (i.e., Chenopodium berlandieri) are considered noxious weeds in the Midwest to maize farmers, even though a thousand years ago in the same region indigenous agriculturalists would have been growing domesticated varieties of both plants and regarding neither of them as weeds. All that said, is there anything scientifically objective about this “noxious weed” classification?

    1. Hello Kevin,

      Your excellent examples illustrate perfectly that harm is in the eye of the beholder. And, you are right that the species you mentioned are particularly common in areas where other plants have difficulty growing. Besides range lands, common habitats of spotted knapweed (described for North Dakota) are highways, waterways, railroad tracks, pipelines and recently installed utility lines. The common complaint about sk is that it reduces the quality of pastureland, as you described.–Mark

  16. It is striking to me how many analogies this native non-native discussion draws to issues of human immigration as well. There seems to be a general bias towards nostalgia and focus on negative impacts of immigration as opposed to the benefits that newcomers can and often do bring. Here I like the idea from Boym of Reflective Nostalgia for integrating newcomers.

    I completely agree with some of the comments here regarding the seeking of open environmental niches to occupy or compete for by newcomer species.

    Tensions of defining “nature” and what changes in a given ecology can be seen as acceptable or not. It seems that we more readily disapprove of changes when they negatively affect humans, whether economically or even in terms of aesthetic enjoyment of a landscape.

    We seem to require a balance between the extremes of striving for a stasis which is unachievable and inherently non natural versus the apathetic ignoring of human impacts on introduction of non-native species. In some ways, removal of non-native species by humans can and does result in many more negative impacts, considering application of chemical pesticides or even new human introduced species as predatory controls.

    My question for Mark is whether you see a trend in the direction of the conservation field in terms of a more nuanced approach to restoration that acknowledges these new and often valuable equilibria?

    1. Hello Paul, thanks for your astute comments. Yes, I am beginning to see some movement in restoration ecology toward managing the environment for the future instead of recreating the past. Restoration ecology has several decades of momentum operating now and so it will likely be a while before the field as a whole embraces the new perspective. And yes there certainly are similarities between the views of nonnative species and the views of immigrants. Both are products of a nativist perspective.–Mark

  17. Thank you again to Mark, and to everyone who took time to leave thoughtful questions and comments.

    We really appreciate everyone’s engagment and commitment, which we feel has gone a very long way to making this online format work. At this stage, I’d like to draw this virtual keynote to a close, and encourage everyone to please check out the next presentation and set of talks as part of Week Two of the Feral conference (of course, as with a non-virtual conference, please feel free to continue your discussions!).

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