Assisted Migration in Normative and Scientific Context


Assisted migration (AM), an ecosystem engineering technology, is receiving increasing attention and significant support as a means to save biodiversity in a changing climate. Few substantive, or not obviously deficient, reasons have been offered for why pursuing this conservation goal via these means might be good. Some proponents of AM, including those who identify themselves as “pragmatists,” even suggest there is little need for such argument. We survey the principal reasons offered for AM, as well as reasons offered for not offering reasons. As exemplified by the case for translocating whitebark pine, which may at first seem especially strong, we note the incongruence of framing the goal of AM in terms of “saving biodiversity,” neglect of some crucial moral questions, marginalization of normative and scientific context when AM is cast as the lesser of two evils in a “crisis,” doubtful validity and, in any case, marginal importance of arguments that AM projects ought to be undertaken, inconsistent use of scientific facts, and omission of science that counters sanguine assessments. All told—even in cases such as whitebark pine for which AM may seem most defensible—there is little reason to think that AM projects are good as means to “save biodiversity,” or good as means to other goals that have accreted into arguments for these projects.

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  1. 1.

    Hällfors et al. (2014) discuss the surfeit of names for assisted migration, none of which were mentioned by Peters and Darling (1985). The pleas of some to standardize terminology—by attaching specific names to specific kinds of projects that differ in goals or conditions imposed—have so far been ignored. Nothing substantive is at stake in our choice of the name "assisted migration."

  2. 2.

    Halfway to ecosystem services are "ecosystem functions" or functional properties of an ecosystem that some ecosystem engineers want to engineer into some ecosystems that lack them. Among those who advocate translocating organisms to bolster certain properties are Lunt et al. (2013). We remark on the normative relevance of these properties in our later discussion of AM for whitebark pine.

  3. 3.

    See Schwartz et al. (2012, p. 733, Table 1) for another tabulation of project types involving moving organisms to some selected locale.

  4. 4.

    The “Missing and Hazy Moral and Scientific Context” section takes up the exceptions.

  5. 5.

    The worry that stakeholders with morally objectionable goals may prevail is not abstract. This, precisely, has happened in the UN-affiliated Intergovernmental Panel on Biodiversity and Ecosystem Services (IPBES). With destructive corporations included as "stakeholders", the IPBES have adopted a framework that essentially places its imprimatur on those corporations' destructive behavior (Maier and Feest 2015). See also Maier (2016) on including stakeholders.

  6. 6.

    The term "socioeconomic data" may also refer to factors other than actual desires and cultural norms, which are normatively relevant—for example, human safety.

  7. 7.

    That economic value reflects not just willingness but ability to pay entails that it disproportionately represents the actual desires of the rich.

  8. 8.

    For example, I am justified in my moral unconcern about the risk of my stepping on sidewalk cracks as I stroll downtown.

  9. 9.

    The phrase "ethical challenges" comes from the title of Schwartz et al. (2012), discussed just below in the main text.

  10. 10.

    For example, torture by even the best methods does not make its practice good.

  11. 11.

    The ubiquitous phrase "ecosystem integrity" is used in multifarious ways, often as an approximate synonym for "ecosystem health." These two phrases jointly embody a concept that formerly was referred to as "the balance of nature."

  12. 12.

    With his suggestion that the value of species is essentially intertwined with its particular relationships, Sandler (2010, 2012, 2013) is one of the few who not only avoids but also rejects the assumption that the goodness of a thing entails a duty to promote its continued existence: For him a species' continued existence is not good absent these relationships.

  13. 13.

    While the need to research and thoroughly understand diseases transmitted by translocated organisms is often acknowledged, Dodd (2005, p. 268) highlights other, seldom acknowledged investigative requirements regarding: the causes for decline (some of which may be masked by the most obvious ones); the habitat, demographic, and biophysical factors that constrain every stage of the organism's life history; and the organism's population genetics alongside (for many animals) its social structure. Pedlar et al. (2011, p. 766) suggest how formidable is the investigative task for trees when they state, "the existence of established provenance trials, seed transfer guidelines, seed procurement systems, and plantation establishment protocols makes AM considerably more feasible for most commercial tree species than for most species of conservation concern."

  14. 14.

    A translocated organism's invasiveness can manifest only after decades (Simberloff 2013, pp. 92–96).

  15. 15.

    It is important to note that our complaint about the naïve pretensions of AM as a significant means of "saving biodiversity" is different in kind as well as in scope from the commonly voiced complaint that devoting too many resources to AM might undercut other kinds of worthwhile conservation efforts. The latter complaint is about misjudging the allocation of resources. In contrast, our complaint calls into question that it is even possible for AM to accomplish what it is supposed to—even if all conservation resources worldwide were dedicated to them.

  16. 16.

    Palmer and Larson (2014, p. 647) are an exception in allowing that whitebark pine is subject to a "multiplicity of threats", some of which may be considered independently of climate change.

  17. 17.

    Mention of these other means should not be interpreted as advocacy.

  18. 18.

    Jared Farmer (2013, Part Two, Eucalypts: The Taxonomy of Belonging) vividly recounts this tale.

  19. 19.

    Many of these refuges—Dawes Arboretum in Newark, OH, Hoyt Arboretum in Portland, OR, Tilden Regional Park's Regional Park Botanic Garden in Berkeley, CA, and the United States National Arboretum in Washington, DC—are far removed from the tree's "native" montane haunts or any habitat that even remotely resembles them. The websites for these facilities document their various specimens.

  20. 20.

    The verdict on this possibility is not decided by the failure of a massive campaign in the early and mid-20th century to eradicate WPBR throughout the United States by eradicating native and introduced species of Ribes (Maloy 1997). This campaign, impossibly large in scope, was also waged in ignorance of more recently uncovered (McDonald et al. 2006; Zambino et al. 2006) host capabilities of Pedicularis and Castilleja spp. It also led to a successful genetics program to develop rust-resistant western pine (Pinus monticola) (Maloy 1997).

  21. 21.

    See, for example, Simberloff (2013, p. 66).

  22. 22.

    One might hope that this discussion would fill the lacuna left in Larson and Palmer (2013, pp. 17–18) where these authors also tout the potential for translocations to bolster ecosystem services, but offer no substantive reason to support this claim.

  23. 23.

    See Maier (2012, pp. 173–174) for more discussion of the indifference of services to particular service-providers.

  24. 24.

    Eucalyptus pauciflora has even earned the imprimatur of the Royal Horticultural Society, with its Award of Garden Merit for one subspecies.

  25. 25.

    It is worth observing that the proposition of "conserving" or bolstering ecosystem properties that benefit people differs substantially and substantively from "conserving biodiversity"—particularly, the number and identity of species in ecosystems (Maier 2012; Maris 2014; Schröter et al. 2014). This observation has led to an enormous research program that has spent decades attempting to show that biodiversity per se is the basis of some functional properties (Tilman et al. 2014). Serious questions about the validity of this research remain. But even if doubts about the research were allayed, the normative relevance of these "functions" would remain in doubt.

  26. 26.

    Maier (2012, §6.9) details how the related claim that biodiversity more generally has option value (in the economic sense) unravels.

  27. 27.

    This is essentially the credo of novel ecosystem engineering, which we touch on just below in the main text. The credo admits many rationales, including many that have little or nothing to do with any commonsense notion of "conserving nature," for engineering re-arrangements of ecosystems.

  28. 28.

    Maier (2016) more fully discusses the single-premise version of the novel ecosystem licensing argument and its variants.

  29. 29.

    Hale et al. (2013, p. 68) present an " 'Argument from Reparation,' which, suggests that our obligations to assist in adaptation stem from a moral obligation to right prior wrongs." These obligations, they say, "rest on a prior failure to justify one’s actions." However they, like Palmer and Larson, neglect to discuss a number of critical elements, which a credible reparation argument must include. The most basic are: what, exactly the "prior wrongs" consist of, what or whom (if any particular things) is wronged, and what reasons we have to consider some particular "assisted adaptation" measure to constitute the morally required reparation actions. At one point, Hale et al. hint that nature is the thing that has been wronged by suggesting that restituting actions be taken "on behalf of nature." But this helps little, absent some plausible account of what it means to wrong nature and how, exactly, adaptive interventions have moral significance as acts of restitution.

  30. 30.

    For a raft of other ways in which an organism's introduction may trigger prediction-defying effects, see Simberloff (2013, pp. 85–96).

  31. 31.

    While these animals are all predators and Clark's Nutcracker is not, the general principle remains. Predation is but one of multiple means of placing pressure on the populations of other creatures—as illustrated by the barred owl's displacement of spotted owl populations in the U.S. Pacific northwest.

  32. 32.

    Recall Dodd and Seigel's (1991) report of less than a 20 % "success" rate for amphibian relocations.

  33. 33.

    Maritime pine (P. pinaster) and Douglas fir (Pseudotsuga menziessii) growing in close proximity to infected Monterey pines appear unaffected by the previously unknown oomycete (Durán et al. 2008, p. 726).


  1. Albrecht, G. A., Brooke, C., Bennett, D. H., & Garnett, S. T. (2013). The ethics of assisted colonization in the age of anthropogenic climate change. Journal of Agricultural and Environmental Ethics, 26(4), 827–845.

    Article  Google Scholar 

  2. Aubin, I., Garbe, C. M., Colombo, S., Drever, C. R., McKenney, D. W., Messier, C., et al. (2011). Why we disagree about assisted migration: Ethical implications of a key debate regarding the future of Canada’s forests. The Forestry Chronicle, 87(6), 755–765.

    Article  Google Scholar 

  3. Buma, B. (2013). Don’t give up just yet: Maintaining species, services and systems in a changing world. Ethics Policy and Environment, 16(1), 33–36.

    Article  Google Scholar 

  4. Cripps, C. L., & Antibus, R. (2011). Native ectomycorrhizal fungi of limber and whitebark pine: Necessary for sustainability?. In R. E. Keane, D. F. Tomback, M. P. Murray, & C. M. Smith (eds.), The future of high-elevation five-needle white pines in Western North America: Proceedings of the high five symposium, 2830 June 2010, Missoula, MT Proceedings RMRS-P-63 (pp. 37–44). Fort Collins, CO: USDA FS, Rocky Mountain Research Station.

  5. Cripps, C. L., & Grimme, E. (2011). Inoculation and successful colonization of whitebark pine seedlings with native mycorrhizal fungi under greenhouse conditions. In R. E. Keane, D. F. Tomback, M. P. Murray, & C. M. Smith (eds.). The future of high-elevation five-needle white pines in Western North America: Proceedings of the high five symposium, 2830 June 2010, Missoula, MT Proceedings RMRS-P-63 (pp. 312–322). Fort Collins, CO: USDA FS, Rocky Mountain Research Station.

  6. Davis, M. A., Grime, J. P., & Thompson, K. (2000). Fluctuating resources in plant communities: A general theory of invasibility. Journal of Ecology, 88, 528–534.

    Article  Google Scholar 

  7. Dodd, C. K., Jr. (2005). Population Manipulations. In M. Lannoo (Ed.), Amphibian declines: The conservation status of United States species (pp. 265–270). Berkeley: University of California Press.

    Google Scholar 

  8. Dodd, C. K., Jr., & Seigel, R. A. (1991). Relocation, repatriation, and translocation of amphibians and reptiles: Are they conservation strategies that work? Herpetologica, 47(3), 336–350.

    Google Scholar 

  9. Durán, A., Gryzenhout, M., Slippers, B., Ahumada, R., Rotella, A., Flores, F., et al. (2008). Phytophthora pinifolia sp. nov. associated with a serious needle disease of Pinus radiata in Chile. Plant Pathology, 57, 715–727.

    Article  Google Scholar 

  10. Goldfarb, B. (2015). Beaver fever. High Country News, 47(9), 7–23.

    Google Scholar 

  11. Hale, B., Hermans, A. P., & Lee, A. (2013). Climate adaptation, moral reparation, and the baseline problem. In S. C. Moser & M. T. Boykoff (Eds.), Successful adaptation to climate change: Linking science and policy in a rapidly changing world (pp. 67–80). Milton Park, Abingdon, UK: Routledge.

    Google Scholar 

  12. Hällfors, M. H., Vaara, E. M., Hyvärinen, M., Oksanen, M., Schulman, L. E., Siipi, H., & Lehvävirta, S. (2014). Coming to terms with the concept of moving species threatened by climate change—A systematic review of the terminology and definitions. PLoS One, 9(7), e102979.

  13. Helfer, S. (2014). Rust fungi and global change. New Phytologist, 201(3), 770–780.

    Article  Google Scholar 

  14. Hewitt, N., Klenk, N., Smith, A. L., Bazely, D. R., Yan, N., Wood, S., et al. (2011). Taking stock of the assisted migration debate. Biological Conservation, 144(11), 2560–2572.

    Article  Google Scholar 

  15. Hobbs, R. J., Higgs, E. S., & Harris, J. A. (2014). Novel ecosystems: Concept or inconvenient reality? A response to Murcia et al. Trends in Ecology & Evolution, 29(12), 645–646.

    Article  Google Scholar 

  16. Hoegh-Guldberg, O., Hughes, L., McIntyre, S., Lindenmayer, D. B., Parmesan, C., Possingham, H. P., et al. (2008). Assisted colonization and rapid climate change. Science, 321(5887), 345–346.

    Article  Google Scholar 

  17. Hooper, D. U., Chapin, F. S., I. I. I., Ewel, J. J., Hector, A., Inchausti, P., Lavorel, S., et al. (2005). Effects of biodiversity on ecosystem functioning: A consensus of current knowledge. Ecological Monographs, 75(1), 3–35.

    Article  Google Scholar 

  18. Hunter, M. M. (2007). Climate change and moving species: Furthering the debate on assisted colonization. Conservation Biology, 21(5), 1356–1358.

    Article  Google Scholar 

  19. Karlman, M. (2001). Risks associated with the introduction of Pinus contorta in northern Sweden with respect to pathogens. Forest Ecology and Management, 141, 97–105.

    Article  Google Scholar 

  20. Keane, R. E., Tomback, D. F., Aubry, C. A., Bower, A. D., Campbell, E. M., Cripps, C. L., Jenkins, M. B., Manning, M., McKinney, S. T. Murray, M. P., Perkins, D. L., Reinhart, D. P., Ryan, C., Schoettle, A. W., & Smith, C. M. 2012. A range-wide restoration strategy for whitebark pine (Pinus albicaulis). General technical report RMRS-GTR-279. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

  21. Klenk, N. L., & Larson, B. M. H. (2013). A rhetorical analysis of the scientific debate over assisted colonization. Environmental Science & Policy, 33, 9–18.

    Article  Google Scholar 

  22. Larson, B. M. H., & Palmer, C. (2013). Assisted colonization is no panacea, but let’s not discount it either. Ethics Policy and Environment, 16(1), 16–18.

    Article  Google Scholar 

  23. Lunt, I. D., Byrne, M., Hellmann, J. J., Mitchell, N. J., Garnett, S. T., Hayward, M. W., et al. (2013). Using assisted colonisation to conserve biodiversity and restore ecosystem function under climate change. Biological Conservation, 157, 172–177.

    Article  Google Scholar 

  24. Maier, D. S. (2012). What’s so good about biodiversity? A call for better reasoning about nature’s value. Dordrecht: Springer.

    Google Scholar 

  25. Maier, D.S. (2016). Taking nature seriously in the anthropocene. Environmental Philosophy, 13(1), 1–33.

  26. Maier, D. S., & Feest, A. (2015). The IPBES conceptual framework: An unhelpful start. Journal of Agricultural and Environmental Ethics,. doi:10.1007/s10806-015-9584-5.

    Google Scholar 

  27. Maloy, O. C. (1997). White pine blister rust control in North America: A case history. Annual review of Phytopathology, 35, 87–109.

    Article  Google Scholar 

  28. Maloy, O. C. (2001). White pine blister rust. Plant Health Progress,. doi:10.1094/PHP-2001-0924-01-HM.

    Google Scholar 

  29. Maris, V. (2014). Nature à Vendre: Les Limites des Services Écosystémiques. Versailles: Éditions Quæ.

    Google Scholar 

  30. McDonald, G. I., Richardson, B. A., Zambino, P. J., Klopfenstein, N. B., & Kim, M.-X. (2006). Pedicularis and Castilleja are natural hosts of Cronartium ribicola in North America: A first report. Forest Pathology, 36, 73–82.

    Article  Google Scholar 

  31. McLachlan, J. S., Hellmann, J. J., & Schwartz, M. W. (2007). A framework for debate of assisted migration in an era of climate change. Conservation Biology, 21(2), 297–302.

    Article  Google Scholar 

  32. Millennium Ecosystem Assessment. (2005). Ecosystems and human well-being: Biodiversity synthesis. Washington, DC: World Resources Institute.

    Google Scholar 

  33. Minteer, B. A. (2012). Refounding environmental ethics: Pragmatism, principle, and practice. Philadelphia: Temple University Press.

    Google Scholar 

  34. Minteer, B. A., & Collins, J. P. (2010). Move it or lose it? The ecological ethics of relocating species under climate change. Ecological Applications, 20(7), 1801–1804.

    Article  Google Scholar 

  35. Minteer, B. A., & Collins, J. P. (2012). Species conservation, rapid environmental change, and ecological ethics. Nature Education Knowledge, 3(10), 14

  36. Murcia, Ca., Aronson, J., Kattan, G. H., Moreno-Mateos, D., Dixon, K., & Simberloff, D. (2014). A critique of the ‘novel ecosystem’ concept. Trends in Ecology & Evolution, 29(10), 548–553.

    Article  Google Scholar 

  37. Norment, C. J. (2014). Relicts of a beautiful sea: Survival, extinction, and conservation in a desert world. Chapel Hill: The University of North Carolina Press.

    Google Scholar 

  38. Palmer, C. (2010). Animal ethics in context. New York: Columbia University Press.

    Google Scholar 

  39. Palmer, C. (2012). Can we—and should we—make reparation to ‘nature’? In W. P. Kabasenche, M. O’. Rourke, & M. H. Slater (Eds.), Topics in contemporary philosophy: Environment: Philosophy, science, and ethics (pp. 201–221). Cambridge, MA, USA: MIT Press.

    Google Scholar 

  40. Palmer, C., & Larson, B. M. H. (2014). Should we move the whitebark pine? Assisted migration, ethics, and global environmental change. Environmental Values, 23(6), 641–662.

    Article  Google Scholar 

  41. Parfit, D. (2011). On what matters. Oxford: Oxford University Press.

    Google Scholar 

  42. Pedlar, J. H., McKenney, D. W., Beaulieu, J., Colombo, S. J., McLachlan, J. S., & O’Neill, G. A. (2011). The implementation of assisted migration in Canadian forests. The Forestry Chronicle, 87(6), 766–777.

    Article  Google Scholar 

  43. Peters, R. L., & Darling, J. D. S. (1985). The greenhouse effect and nature reserves. BioScience, 35(11), 707–717.

    Article  Google Scholar 

  44. Ricciardi, A., & Simberloff, D. (2009). Assisted colonization is not a viable conservation strategy. Trends in Ecology & Evolution, 24(5), 248–253.

    Article  Google Scholar 

  45. Richardson, D. M., Hellmann, J. J., McLachlan, J. S., Sax, D. F., Schwartz, M. W., Gonzalez, P., et al. (2009). Multidimensional evaluation of managed relocation. PNAS, 106(24), 9721–9724.

    Article  Google Scholar 

  46. Sandler, R. (2010). The value of species and the ethical foundations of assisted migration. Conservation Biology, 24(2), 424–431.

    Article  Google Scholar 

  47. Sandler, R. (2012). The ethics of species: An introduction. Cambridge: Cambridge University Press.

    Google Scholar 

  48. Sandler, R. (2013). Climate change and ecosystem management. Ethics Policy and Environment, 16(1), 1–15.

    Article  Google Scholar 

  49. Schlaepfer, M. A., Helenbrook, W. D., Searing, K. B., & Shoemaker, K. T. (2009). Assisted colonization: evaluating contrasting management actions (and values) in the face of uncertainty. Trends in Ecology & Evolution, 24(9), 471–472.

    Article  Google Scholar 

  50. Schoettle, A. W., & Sniezko, R. A. (2007). Proactive intervention to sustain high-elevation pine ecosystems threatened by white pine blister rust. Journal of Forestry Research, 12, 327–336.

    Article  Google Scholar 

  51. Schröter, M., van der Zanden, E. H., van Oudenhoven, A. P. E., Remme, R. P., Serna-Chavez, H. M., de Groot, R. S., & Opdam, P. (2014). Ecosystem services as a contested concept: A synthesis of critique and counter-arguments. Conservation Letters 7, 514–523.

  52. Schwartz, M. W., Hellmann, J. J., McLachlan, J. M., Sax, D. F., Borevitz, J. O., Brennan, J., et al. (2012). Managed relocation: Integrating the scientific, regulatory, and ethical challenges. BioScience, 62(8), 732–743.

    Article  Google Scholar 

  53. Seddon, P. J. (2010). From reintroduction to assisted colonization: moving along the conservation translocation spectrum. Restoration Ecology, 18(6), 796–802.

    Article  Google Scholar 

  54. Siipi, H. & Ahteeneuu, M.O. (2016). “Moral Relevance of Range and Naturalness in Assisted Migration.” Environmental Values, 25(4), 465–483.

  55. Simberloff, D. (1991). Keystone species and community effects of biological introductions. In L. R. Ginzburg (Ed.), Assessing ecological risks of biotechnology (pp. 1–19). Boston, MA: Butterworth-Heinemann.

    Google Scholar 

  56. Simberloff, D. (2013). Invasive species. What everyone needs to know. New York: Oxford University Press.

    Google Scholar 

  57. Tilman, D., Isbell, F., & Cowles, J. M. (2014). Biodiversity and ecosystem functioning. Annual Review of Ecology Evolution and Systematics, 45, 471–493.

    Article  Google Scholar 

  58. Zambino, P. J., Richardson, B. A., McDonald, G. I., Klopfenstein, N. B., & Kim, M.-S. (2006). Non-ribes alternate hosts of white pine blister rust: What this discovery means for whitebark pine. Nutcracker Notes, Whitebark Pine Ecosystem Foundation, 10, 6–7.

    Google Scholar 

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Maier, D., Simberloff, D. Assisted Migration in Normative and Scientific Context. J Agric Environ Ethics 29, 857–882 (2016).

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  • Assisted migration
  • Conservation
  • Ecosystem engineering
  • Biodiversity
  • Climate
  • Change
  • Whitebark pine