Skip to main content

Generic ecological impact assessments of alien species in Norway: a semi-quantitative set of criteria

Abstract

The ecological impact assessment scheme that has been developed to classify alien species in Norway is presented. The underlying set of criteria enables a generic and semi-quantitative impact assessment of alien species. The criteria produce a classification of alien species that is testable, transparent and easily adjustable to novel evidence or environmental change. This gives a high scientific and political legitimacy to the end product and enables an effective prioritization of management efforts, while at the same time paying attention to the precautionary principle. The criteria chosen are applicable to all species regardless of taxonomic position. This makes the assessment scheme comparable to the Red List criteria used to classify threatened species. The impact of alien species is expressed along two independent axes, one measuring invasion potential, the other ecological effects. Using this two-dimensional approach, the categorization captures the ecological impact of alien species, which is the product rather than the sum of spread and effect. Invasion potential is assessed using three criteria, including expected population lifetime and expansion rate. Ecological effects are evaluated using six criteria, including interactions with native species, changes in landscape types, and the potential to transmit genes or parasites. Effects on threatened species or landscape types receive greater weightings.

This is a preview of subscription content, access via your institution.

Fig. 1
Fig. 2
Fig. 3

References

  • Alberternst B (1998) Biologie, Ökologie, Verbreitung und Kontrolle von Reynoutria-Sippen in Baden-Württemberg. Culterra 23:1–198

    Google Scholar 

  • Amiri A, Talebi AA, Zamani AA, Kamali K (2010) Effect of temperature on demographic parameters of the hawthorn red midget moth, Phyllonorycter corylifoliella, on apple. J Insect Sci 10(134):1–12

    Article  Google Scholar 

  • Augustin S, Guichard S, Heitland W, Freise J, Svatoš A, Gilbert M (2009) Monitoring and dispersal of the invading Gracillariidae Cameraria ohridella. J Appl Entomol 133:58–66

    Google Scholar 

  • Baiser B, Lockwood JL, La Puma D, Aronson MFJ (2008) A perfect storm: two ecosystem engineers interact to degrade deciduous forests of New Jersey. Biol Invasions 10:785–795

    Article  Google Scholar 

  • Baker R, Hulme P, Copp GH, Thomas M, Black R, Haysom K (2005) UK non-native organism risk assessment scheme user manual: version 3.3. Great Britain Non-native Species Secretariat, New York

    Google Scholar 

  • Beissinger SR, McCollough DR (eds) (2002) Population viability analysis. University of Chicago Press, Chicago

    Google Scholar 

  • Blackburn TM, Lockwood JL, Cassey P (2009) Avian invasions: the ecology and evolution of exotic birds. Oxford University Press, Oxford

    Book  Google Scholar 

  • Bomford M (2008) Risk assessment models for establishment of exotic vertebrates in Australia and New Zealand. Invasive Animals Cooperative Research Centre, Canberra

    Google Scholar 

  • Borgstrøm R, Brittain JE, Hasle K, Skjølås S, Dokk JG (1996) Reduced recruitment in brown trout Salmo trutta, the role of interactions with the minnow Phoxinus phoxinus. Nord J Freshw Res 72:30–38

    Google Scholar 

  • Branquart E (2009) Guidelines for environmental impact assessment and list classification of non-native organisms in Belgium: version 2.6. Belgian Forum on Invasive Species, Bruxelles

    Google Scholar 

  • Brown PMJ, Adriaens T, Bathon H et al (2008) Harmonia axyridis in Europe: spread and distribution of a non-native coccinellid. BioControl 53:5–21

    Article  Google Scholar 

  • Brunel S, Branquart E, Fried G et al (2010) The EPPO prioritization process for invasive alien plants. Bull OEPP 40:407–422

    Google Scholar 

  • Buhl O, Falck P, Jørgensen B, Karsholt O, Larsen K, Vilhelmsen F (2003) Fund af småsommerfugle fra Danmark i 2002 (Lepidoptera). Entomol Medd 71:65–76

    Google Scholar 

  • Burgman MA (2002) Flaws in subjective assessments of ecological risks and means for correcting them. Aust J Environ Manag 8:219–226

    Google Scholar 

  • Butchard SHM (2008) Red List indices to measure the sustainability of species use and impacts of invasive alien species. Bird Conserv Int 18(Suppl):S245–S262

    Google Scholar 

  • CEC (2009) Trinational risk assessment guidelines for aquatic alien invasive species. Commission for Environmental Cooperation, Montréal

    Google Scholar 

  • CEU (2009) A mid-term assessment of implementing the EU biodiversity action plan and towards an EU strategy on invasive alien species. Council of the European Union, Bruxelles

    Google Scholar 

  • CFIA (2001) Canadian PHRA rating guidelines. Canadian Food Inspection Agency, Montreal

    Google Scholar 

  • Clark JS, Lewis M, McLachlan JS, HilleRisLambers J (2003) Estimating population spread: what can we forecast and how well? Ecology 84:1979–1988

    Article  Google Scholar 

  • Colautti RI, Grigorovich IA, MacIsaac HJ (2006) Propagule pressure: a null model for biological invasions. Biol Invasions 8:1023–1037

    Article  Google Scholar 

  • Cox GW (2004) Alien species and evolution: the evolutionary ecology of exotic plants, animals, microbes, and interacting native species. Island Press, Washington DC

    Google Scholar 

  • Deschka G, Dimić N (1986) Cameraria ohridella sp. n. (Lep., Lithocolletidae) aus Mazedonien. Jugoslawien Acta Entomol Jugosl 22:11–23

    Google Scholar 

  • Dextrase AJ, Mandrak NE (2006) Impacts of alien invasive species on freshwater fauna at risk in Canada. Biol Invasions 8:13–24

    Article  Google Scholar 

  • Doak DF, Estes JA, Halpern BS et al (2008) Understanding and predicting ecological dynamics: are major surprises inevitable? Ecology 89:952–961

    PubMed  Article  Google Scholar 

  • Ehrenfeld JG (2010) Ecosystem consequences of biological invasions. Annu Rev Ecol Evol Syst 41:59–80

    Article  Google Scholar 

  • Essl F, Klingenstein F, Nehring S, Otto C, Rabitsch W, Stöhr O (2008) Schwarze Listen invasiver Arten – ein Instrument zur Risikobewertung für die Naturschutz-Praxis. Nat Landsch 83:418–424

    Google Scholar 

  • Essl F, Nehring S, Klingenstein F, Milasowszky N, Nowack C, Rabitsch W (2011) Review of risk assessment systems of IAS in Europe and introducing the German–Austrian Black List Information System (GABLIS). J Nat Conserv 19:339–350

    Article  Google Scholar 

  • Euler T (2011) Der Japanische Staudenknöterich als „Ökosystemingenieur“ in Flussauen. Geogr Rundsch 63(3):59

    Google Scholar 

  • FAO (2004) Pest risk analysis for quarantine pests including analysis of environmental risks and living modified organisms: ISPM no. 11. Food and Agriculture Organization, Roma

    Google Scholar 

  • Fisher J (1953) The collared turtle dove in Europe. Br Birds 46:153–181

    Google Scholar 

  • Freckleton RP, Dowling PM, Dulvy NK (2006) Stochasticity, nonlinearity and instability in biological invasions. In: Cadotte MW, McMahon SM, Fukami T (eds) Conceptual ecology and invasion biology. Springer, Dordrecht, pp 125–146

    Google Scholar 

  • Fremstad E, Elven R (1997) Fremmede planter i Norge. De store Fallopia-artene. Blyttia 55:3–14

    Google Scholar 

  • Gederaas L, Moen TL, Skjelseth S, Hansen L-K (2013) Alien species in Norway: with the Norwegian Black List 2012. Artsdatabanken, Trondheim

  • Gederaas L, Salvesen I, Viken Å (2007) Norsk svarteliste 2007 – økologiske risikovurderinger av fremmede arter. Artsdatabanken, Trondheim

  • Genovesi P, Shine C (2004) European strategy on invasive alien species. Nat Environ Ser 137:1–60

    Google Scholar 

  • Gilbert M, Grégoire J-C, Freise JF, Heitland W (2004) Long-distance dispersal and human population density allow the prediction of invasive patterns in the horse chestnut leafminer. J Anim Ecol 73:459–468

    Article  Google Scholar 

  • Goodenough AE (2010) Are the ecological impacts of alien species misrepresented? A review of the “native good, alien bad” philosophy. Community Ecol 11:13–21

    Article  Google Scholar 

  • Halvorsen R, Andersen T, Blom HH et al (2009) Naturtyper i Norge – teoretisk grunnlag, prinsipper for inndeling og definisjoner. Artsdatabanken, Trondheim

  • Hartvigsen R (1997) Spredning av parasitter ved innvandring og/eller introduksjon av nye fiskearter: spredning av ørekyt (Phoxinus phoxinus) til ørretvassdrag. NINA Oppdragsmeld 466:1–14

    Google Scholar 

  • Hejda M, Pyšek P, Jarosik V (2009) Impact of invasive plants on the species richness, diversity and composition of invaded communities. J Ecol 97:393–403

    Article  Google Scholar 

  • Higgins SN, Vander Zanden MJ (2010) What a difference a species makes: a meta-analysis of dreissenid mussel impact on freshwater ecosystems. Ecol Monogr 80:179–196

    Article  Google Scholar 

  • Hooten MB, Wikle CK (2008) A hierarchical Bayesian non-linear spatio-temporal model for the spread of invasive species with application to the Eurasian collared-dove. Environ Ecol Stat 15:59–70

    Article  Google Scholar 

  • Huang D, Haack RA, Zhang R (2011) Does global warming increase establishment rates of invasive alien species? A centurial time series analysis. PLoS ONE 6:e24733

    PubMed  CAS  Article  Google Scholar 

  • Invasive Species Ireland (2008) Invasive species Ireland risk assessment. National Parks and Wildlife Service/Northern Ireland Environment Agency, Dublin/Belfast

    Google Scholar 

  • IUCN (2000) IUCN guidelines for the prevention of biodiversity loss caused by alien invasive species. International Union for the Conservation of Nature, Gland

    Google Scholar 

  • IUCN (2001) IUCN Red List categories and criteria: version 3.1. International Union for the Conservation of Nature, Cambridge

    Google Scholar 

  • Jäger EJ (1995) Die Gesamtareale von Reynoutria japonica Houtt. und R. sachalinensis (F. Schmidt) Nakai, ihre klimatische Interpretation und Daten zur Ausbreitungsgeschichte. Schrr Vegkd 27:395–403

    Google Scholar 

  • Kålås JA, Viken Å, Henriksen S, Skjelseth S (eds) (2010) Norsk rødliste for arter 2010. Artsdatabanken, Trondheim

    Google Scholar 

  • Keller RP, Lodge DM, Finnoff DC (2007) Risk assessment for invasive species produces net bioeconomic benefits. Proc Natl Acad Sci USA 104:203–207

    PubMed  CAS  Article  Google Scholar 

  • Koch RL (2003) The multicolored Asian beetle, Harmonia axyridis: a review of its biology, uses in biological control, and non-target impacts. J Insect Sci 3(32):1–16

    Google Scholar 

  • Kot M, Lewis MA, van den Driessche P (1996) Dispersal data and the spread of invading organisms. Ecology 77:2027–2042

    Article  Google Scholar 

  • Kumschick S, Nentwig W (2010) Some alien birds have as severe an impact as the most effectual alien mammals in Europe. Biol Conserv 143:2757–2762

    Article  Google Scholar 

  • Lande R, Sæther B-E, Engen S (2003) Stochastic population dynamics in ecology and conservation. Oxford University Press, Oxford

    Book  Google Scholar 

  • Lanzoni A, Accinelli G, Bazzocchi GG, Burgio G (2004) Biological traits and life table of the exotic Harmonia axyridis compared with Hippodamia variegata, and Adalia bipunctata (Col., Coccinellidae). J Appl Entomol 128:298–306

    Article  Google Scholar 

  • Laska MS, Wootton JT (1998) Theoretical concepts and empirical approaches to measuring interaction strength. Ecology 79:461–476

    Article  Google Scholar 

  • Lavergne S, Molofsky J (2007) Increased genetic variation and evolutionary potential drive the success of an invasive grass. Proc Natl Acad Sci USA 104:3883–3888

    PubMed  CAS  Article  Google Scholar 

  • Leigh EG Jr (1981) The average lifetime of a population in a varying environment. J Theor Biol 90:213–239

    PubMed  Article  Google Scholar 

  • Lewis MA, Neubert MG, Caswell H, Clark JS, Shea K (2006) A guide to calculating discrete-time invasion rates from data. In: Cadotte MW, McMahon SM, Fukami T (eds) Conceptual ecology and invasion biology. Springer, Dordrecht, pp 169–192

    Google Scholar 

  • Lindgaard A, Henriksen S (eds) (2011) Norsk rødliste for naturtyper 2011. Artsdatabanken, Trondheim

    Google Scholar 

  • Lockwood JL, Cassey P, Blackburn T (2005) The role of propagule pressure in explaining species invasions. Trends Ecol Evol 20:223–228

    PubMed  Article  Google Scholar 

  • Mace GM, Lande R (1991) Assessing extinction threats: toward a reevaluation of IUCN threatened species categories. Conserv Biol 5:148–157

    Article  Google Scholar 

  • Mack RN, Simberloff D, Lonsdale WM, Evans H, Clout M, Bazzaz FA (2000) Biotic invasions: causes, epidemiology, global consequences, and control. Ecol Appl 10:689–710

    Article  Google Scholar 

  • Mainka SA, Howard GW (2010) Climate change and invasive species: double jeopardy. Integr Zool 5:102–111

    PubMed  Article  Google Scholar 

  • Makowski D, Mittinty MN (2010) Comparison of scoring systems for invasive pests using ROC analysis and Monte Carlo simulations. Risk Anal 30:906–915

    PubMed  Article  Google Scholar 

  • McCarthy MA, Keith D, Tietjen J et al (2004) Comparing predictions of extinction risk using models and subjective judgement. Acta Oecol 26:67–74

    Article  Google Scholar 

  • Miljøministeriet (2008) Handlingsplan for invasive arter. Miljøministeriet, København

  • Moore C (2011) Invasives: classify with care. Science 333:936

    PubMed  CAS  Article  Google Scholar 

  • Morris WF, Doak DF (2002) Quantitative conservation biology: theory and practice of population viability analysis. Sinauer, Sunderland

    Google Scholar 

  • Mrosovsky N (1997) IUCN’s credibility critically endangered. Nature 389:436

    CAS  Article  Google Scholar 

  • Murphy HT, VanDerWal J, Lovett-Doust L, Lovett-Doust J (2006) Invasiveness in exotic plants: immigration and naturalization in an ecological continuum. In: Cadotte MW, McMahon SM, Fukami T (eds) Conceptual ecology and invasion biology. Springer, Dordrecht, pp 65–105

    Google Scholar 

  • Museth J, Hesthagen T, Sandlund OT, Thorstad E, Ugedal O (2007) The history of the European minnow in Norway: from harmless species to pest. J Fish Biol 71(Suppl D):184–195

    Article  Google Scholar 

  • Næstad F, Brittain JE (2010) Long-term changes in the littoral benthos of a Norwegian subalpine lake following the introduction of the European minnow (Phoxinus phoxinus). Hydrobiologia 642:71–79

    Article  CAS  Google Scholar 

  • Neubert MG, Kot M, Lewis MA (2000) Invasion speeds in fluctuating environments. Proc R Soc B 267:1603–1610, 2568–2569

    Google Scholar 

  • Norton LR, Firbank LG, Scott A, Watkinson AR (2005) Characterising spatial and temporal variation in the finite rate of population increase across the northern range boundary of the annual grass Vulpia fasciculata. Oecologia 144:407–415

    PubMed  Article  Google Scholar 

  • Novak M, Wootton JT (2008) Estimating nonlinear interaction strengths: an observation-based method for species-rich food webs. Ecology 89:2083–2089

    PubMed  Article  Google Scholar 

  • Paine RT (1992) Food-web analysis through field measurement of per capita interaction strength. Nature 355:73–75

    Article  Google Scholar 

  • Parker IM, Simberloff D, Lonsdale WM et al (1999) Impact: toward a framework for understanding the ecological effects of invaders. Biol Invasions 1:3–19

    Article  Google Scholar 

  • Pejchar L, Mooney HA (2009) Invasive species, ecosystem services and human well-being. Trends Ecol Evol 24:497–504

    PubMed  Article  Google Scholar 

  • Pell JK, Baverstock J, Roy HE, Ware RL, Majerus MEN (2008) Intraguild predation involving Harmonia axyridis: a review of current knowledge and future perspectives. BioControl 53:147–168

    Article  Google Scholar 

  • Petrovskii SV, Li B-L (2006) Exactly solvable models of biological invasions. Chapman & Hall, Boca Raton

    Google Scholar 

  • Pheloung PC, Williams PA, Halloy SR (1999) A weed risk assessment model for use as a biosecurity tool evaluating plant introductions. J Environ Manag 57:239–251

    Article  Google Scholar 

  • Pimentel D, Zuniga R, Morrison D (2005) Update on the environmental and economic costs associated with alien-invasive species in the United States. Ecol Econ 52:273–288

    Article  Google Scholar 

  • PLH [European Food Safety Authority Panel on Plant Health] (2011) Guidance on the environmental risk assessment of plant pests. EFSA J 9:2490

    Google Scholar 

  • Power ME, Tilman D, Estes JA et al (1996) Challenges in the quest for keystones. BioScience 46:609–620

    Google Scholar 

  • Pyšek P, Richardson DM, Rejmánek M, Webster GL, Williamson M, Kirschner J (2004) Alien plants in checklists and floras: towards a better communication between taxonomists and ecologists. Taxon 53:131–143

    Article  Google Scholar 

  • R development core team (2011) R: a language and environment for statistical computing, version 2.12.2. R Foundation for Statistical Computing, Wien url: http://www.r-project.org

  • Ree V (1994) Tyrkerdue Streptopelia decaocto. In: Gjershaug JO, Thingstad PG, Eldøy S, Byrkjeland S (eds) Norsk fugleatlas: Hekkefuglenes utbredelse og bestandsstatus i Norge. Norsk ornitologisk forening, Klæbu, pp 266–267

    Google Scholar 

  • Richardson DM, Pyšek P, Rejmánek M, Barbour MG, Panetta FD, West CJ (2000) Naturalization and invasion of alien plants: concepts and definitions. Divers Distrib 6:93–107

    Google Scholar 

  • Rocha G, Hidalgo SJ (2000) The spread of the collared dove Streptopelia decaocto in Europe: colonization patterns in the West of the Iberian Peninsula. Bird Study 49:11–16

    Article  Google Scholar 

  • Roy HE, Adriaens T, Isaac NJB et al (2012) Invasive alien predator causes rapid declines of native European ladybirds. Divers Distrib 18:717–725

    Google Scholar 

  • Sæthre M-G, Staverløkk A, Hågvar EB (2010) Stowaways in horticultural plants imported from the Netherlands, Germany and Denmark. Nor J Entomol 57:25–35

    Google Scholar 

  • Shigesada N, Kawasaki K (1997) Biological invasions: theory and practice. Oxford University Press, Oxford

    Google Scholar 

  • Simberloff D (2005) Non-native species do threaten the natural environment! J Agric Environ Ethics 18:595–607

    Article  Google Scholar 

  • Skarpaas O (2012) Levedyktighetsanalyse som grunnlag for risikovurdering av fremmede karplanter. NINA Minirapp 361:1–58

    Google Scholar 

  • Staverløkk A, Sæthre M-G (2008) Funn av harlekinmarihøna Harmonia axyridis i Norge. Insekt Nytt 33:8–12

    Google Scholar 

  • Stone ER, Yates JF, Parker AM (1994) Risk communication: absolute versus relative expressions of low-probability risks. Organ Behav Hum Decis Process 60:387–408

    Article  Google Scholar 

  • Sutcliffe OL, Thomas CD, Moss D (1996) Spatial synchrony and asynchrony in butterfly population dynamics. J Anim Ecol 65:85–95

    Article  Google Scholar 

  • Svorkmo-Lundberg M (2006) Tyrkerdue Streptopelia decaocto. In: Svorkmo-Lundberg T, Bakken V, Helberg M, Mork K, Røer JE, Sæbø S (eds) Norsk vinterfuglatlas: Fuglenes utbredelse, bestandsstørrelse og økologi vinterstid. Norsk ornitologisk forening, Trondheim, pp 254–255

    Google Scholar 

  • Syslo JM, Guy CS, Bigelow PE, Doepke PD, Ertel BD, Koel TM (2011) Response of non-native lake trout (Salvelinus namaycush) to 15 years of harvest in Yellowstone Lake, Yellowstone National Park. Can J Fish Aquat Sci 68:2132–2145

    Article  Google Scholar 

  • USDA (2000) Guidelines for pathway-initiated pest risk assessment: version 5.02. United States Department of Agriculture, Riverdale

    Google Scholar 

  • Veit RR, Lewis MA (1996) Dispersal, population growth, and the Allee effect: dynamics of the house finch invasion of eastern North America. Am Nat 148:255–274

    Article  Google Scholar 

  • Venable DL (2007) Bet hedging in a guild of desert annuals. Ecology 88:1086–1090

    PubMed  Article  Google Scholar 

  • Verbrugge LNH, Leuven RSEW, van der Velde G (2010) Evaluation of international risk assessment protocols for exotic species. Rep Environ Sci 352:1–54

    Google Scholar 

  • Vilà M, Basnou C, Pyšek P et al (2010) How well do we understand the impacts of alien species on ecosystem services? A pan-European, cross-taxa assessment. Front Ecol Environ 8:135–144

    Article  Google Scholar 

  • Vose D (2008) Risk analysis: a quantitative guide, 3rd edn. Wiley, Chichester

    Google Scholar 

  • Waples RS, Jensen DW, McClure M (2010) Eco-evolutionary dynamics: fluctuations in population growth rate reduce effective population size in chinook salmon. Ecology 91:902–914

    PubMed  Article  Google Scholar 

  • Ware RL, Majerus MEN (2008) Intraguild predation of immature stages of British and Japanese coccinellids by the invasive ladybird Harmonia axyridis. BioControl 53:169–188

    Article  Google Scholar 

  • Webber BL, Scott JK (2012) Rapid global change: implications for defining natives and aliens. Glob Ecol Biogeogr 21:305–311

    Article  Google Scholar 

  • Weber E, Köhler B, Gelpke G, Perrenoud A, Gigon A (2005) Schlüssel zur Einteilung von Neophyten in der Schweiz in die Schwarze Liste oder die Watch-Liste. Bot Helv 115:169–173

    Article  Google Scholar 

  • White EM, Wilson JC, Clarke AR (2006) Biotic indirect effects: a neglected concept in invasion biology. Divers Distrib 12:443–455

    Article  Google Scholar 

  • Whitney KD, Gabler CA (2008) Rapid evolution in introduced species, “invasive traits” and recipient communities: challenges for predicting invasive potential. Divers Distrib 14:569–580

    Article  Google Scholar 

  • WTO (1994) Agreement on the application of sanitary and phytosanitary measures. World Trade Organization, Genève

    Google Scholar 

Download references

Acknowledgments

The development of the new set of criteria was solicited and funded by The Norwegian Biodiversity Information Centre (Artsdatabanken). Further funding was provided by the Norwegian Directorate for Nature Management (DN). Valuable input, comments and help came from L. Gederaas, S. Henriksen, T.L. Moen, I. Salvesen, H. Sandmark, S. Skjelseth (Artsdatabanken), E. Ødegaard (DN), H.H. Grundt (FlowerPower), M. Crawley (Imperial College), H. Loeng (Institute of Marine Research), R. Andersen (Museum of Natural History and Archaeology at NTNU), R. Elven (Natural History Museum at University of Oslo), L.T. Kristjánsson (Norwegian Directorate of Fisheries), H.P. Brække (Norwegian Food Safety Authority), B.H. Øyen (Norwegian Forest and Landscape Institute), T. Hofsvang (Norwegian Institute for Agricultural and Environmental Research), J.A. Kålås, F. Ødegaard, O.T. Sandlund, O. Skarpaas (Norwegian Institute for Nature Research), R.A. Ims (University of Tromsø) and the anonymous reviewers. We thank N. Straw at Forest Research (UK) for kindly providing observational data.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Hanno Sandvik.

Appendix

Appendix

Estimation of expected population lifetime and expansion rate

Following Leigh (1981; Lande et al. 2003:38–40), expected population lifetime can be estimated as:

$$ \bar{T}_{\text{ext}} = 2\int_{C}^{{N_{0} }} {s\left( x \right)} {\kern 1pt} \;\int_{x}^{\infty } {\frac{1}{s\left( N \right)V\left( N \right)}} \;dN\;dx , $$
(1)

where

$$ s\left( N \right) = e^{{ - 2\int_{C}^{N} {{{M\left( x \right)} \mathord{\left/ {\vphantom {{M\left( x \right)} {V\left( x \right)}}} \right. \kern-\nulldelimiterspace} {V\left( x \right)}}\;dx} }} , $$
(2)
$$ M\left( N \right) = \left( {\uplambda - 1} \right)N\left[ {1 - \left( {\tfrac{N}{K}} \right)^{\uptheta } } \right] , $$
(3)
$$ V\left( N \right) = \upsigma_{\text{d}}^{2} N + \upsigma_{\text{e}}^{2} N^{2} + 2\uprho \upsigma_{\text{e}} \upsigma_{\ln K} \tfrac{\uplambda - 1}{{\bar{K}}}N^{3} + \left( {e^{{\upsigma_{{_{\ln K} }}^{2} }} - 1} \right)\left( {\tfrac{\uplambda - 1}{{\bar{K}}}} \right)^{2} N^{4} , $$
(4)

with C, quasi-extinction threshold; K, carrying capacity; λ = e r, annual multiplicative population growth rate; N 0, current population size; ρ, correlation between growth rate and environmental noise; \( \upsigma_{d}^{2} \), demographic variance; \( \upsigma_{e}^{2} \), environmental variance; \( \upsigma_{\ln K}^{2} \), temporal variance of the carrying capacity; θ, form of the density dependence. An R-script (R development core team 2011) that carries out the estimation of expected population lifetime as described here, is available from the first author (http://www.evol.no/hanno/12/lifetime.htm).

In our analyses, we assumed the quasi-extinction threshold to be 10; carrying capacity to be 100 times current population size; temporal variance of the carrying capacity to be negligible (i.e., \( \upsigma_{\ln K}^{2} \) = 0); and density regulation to be logistic (i.e., θ = 1). Simulations have shown that the estimation of expected population lifetime is quite insensitive to variation in these parameters and in demographic variance (Sandvik and Sæther unpublished data).

Population size was based on reported counts and observations available, accounting for the unreported or undetected fraction of the population (i.e., including levels of uncertainty by dividing known numbers by the estimated or suspected detection rate). Growth rates and variances were based on what is known about the life history of the taxa considered and, were available, on the actual trends of the populations in Norway. In order to obtain intervals, we used the best available estimate as well as a realistic upper limit for each parameter. Table 7 summarises the information used as input to Table 3 including the references consulted.

Table 7 Input values used for the estimation of expected population lifetime of the five example species

An alternative way to estimate expected population lifetime is by use of population viability analyses. Given estimates on extinction risk within a given timeframe, as used in criterion E of the international Red List criteria (IUCN 2001), expected population lifetime can be obtained as

$$ \bar{T}_{\text{ext}} = {{ - \Updelta t} \mathord{\left/ {\vphantom {{ - \Updelta t} {\ln \left( {1 - p} \right)}}} \right. \kern-\nulldelimiterspace} {\ln \left( {1 - p} \right)}} , $$
(5)

where p is the probability of extinction within time interval Δt.

Expansion rate was estimated as the speed \( \bar{v} \) of an assumed invasion front starting from the position of first observation of the species. Corresponding to our definition of expansion rate, the assumed invasion front was, in turn, inferred using all individual observations of the species, irrespective of how the species might have ended up there (locomotion, dispersal, anthropogenic transport etc.). The speed of the invasion front was then obtained using linear regression under the assumption of sampling error and no process variance. An R-script (R development core team 2011) that carries out the estimation of expansion rate as described here, is available from the first author (http://www.evol.no/hanno/12/expans.htm).

The method described may produce unrealistic estimates in cases where an alien species has been introduced a few times at locations that are very far from each other. An alternative definition of expansion rate for such cases would be the sum of the rates estimated from each of the introductions.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Sandvik, H., Sæther, BE., Holmern, T. et al. Generic ecological impact assessments of alien species in Norway: a semi-quantitative set of criteria. Biodivers Conserv 22, 37–62 (2013). https://doi.org/10.1007/s10531-012-0394-z

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s10531-012-0394-z

Keywords

  • Black List criteria
  • Ecological effect
  • Invasion potential
  • Non-native species
  • Quantitative risk assessment
  • Risk classification