invasion biology terminology

The need for a clearly defined and consistent invasion biology terminology has been acknowledged by many sources. ''Invasive species'', or ''invasive exotics'', is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats. ''Invasion biology'' is the study of these organisms and the processes of species invasion.

The terminology in this article contains definitions for invasion biology terms in common usage today, taken from accessible publications. References for each definition are included. Terminology relates primarily to invasion biology terms with some ecology terms included to clarify language and phrases on linked articles.

Introduction

Definitions of "invasive non-indigenous species have been inconsistent", which has led to confusion both in literature and in popular publications (Williams and Meffe 2005). Also, many scientists and managers feel that there is no firm definition of non-indigenous species, native species, exotic species, "and so on, and ecologists do not use the terms consistently." (Shrader-Frechette 2001) Another question asked is whether current language is likely to promote "effective and appropriate action" towards invasive species through cohesive language (Larson 2005). Biologists today spend more time and effort on invasive species work because of the rapid spread, economic cost, and effects on ecological systems, so the importance of effective communication about invasive species is clear. (Larson 2005)

Controversy in invasion biology terms exists because of past usage and because of preferences for certain terms. Even for biologists, defining a species as native may be far from being a straightforward matter of biological classification based on the location or the discipline a biologist is working in (Helmreich 2005). Questions often arise as to what exactly makes a species native as opposed to non-native, because some non-native species have no known negative effects (Woods and Moriarty 2001). Natural biological invasions, generally considered range expansions, and introductions involving human activities are important and could be considered a normal ecological process (Vermeij 2005). Non-native and native species may be sometimes considered invasive, and these invasions often follow human-induced landscape changes, with subsequent damage to existing landscapes a value judgment (Foster and Sandberg 2004). As a result, many important terms relevant to invasion biology, such as invasive, weed, or transient, include qualities that are "open to subjective interpretation" (Colautti and MacIsaac 2004). Sometimes one species can have both beneficial and detrimental effects, such as the Mosquito fish (''Gambusia affinis''), which has been widely introduced because of its suppression of larval mosquitoes, although it also has negative impacts on native species of insects, fish and amphibians (Colautti and MacIsaac 2004).

The large number and current complexity of terms makes interpretation of some of the invasion biology literature challenging and intimidating. Exotic, alien, transplanted, introduced, non-indigenous, and invasive are all words that have been used to describe plants and animals that have been moved beyond their native ranges by humans (Williams and Meffe 2005), along with other terms such as foreign, injurious, aquatic nuisance, pest, non-native, all with a particular implication. Even the use of what seem to be simple, basic terms to articulate ecological concepts "can confuse ideological debates and undermine management efforts" (Colautti and MacIsaac 2004). Attempts to redefine commonly used terms in invasion biology have been difficult because many authors and biologists are particular to a favorite definition (Colautti and MacIsaac 2004). Also, the status and identification of any species as an invader, a weed, or an exotic are "conditioned by cultural and political circumstances." (Robbins 2004)

Terminology

Where words in a sentence are also defined elsewhere in this article, they appear in italics.

;Alien species (See Introduced species)
: Less commonly used in scientific literature but often included in ''population'' publications, public information displays, and educational literature. This term refers to ''species'' that spread beyond their ''native range'', not necessarily harmful, or ''species'' introduced to a new range that establish themselves and spread; similar terms include ''exotic species'', ''foreign species'', ''introduced species'', ''non indigenous species'', and ''non native species'' (Jeschke and Strayer 2005).
; Aquatic nuisance species
: Less commonly used in most literature.
:#A ''nonindigenous species'' that threatens the diversity or abundance of native species or the ecological stability of infested waters, or commercial, agricultural, aquacultural or recreational activities dependent on such waters (EPA 1990).
:#Aquatic ''species'' that causes economic or environmental harm to humans (Heutte and Bella 2003).
:#An aquatic ''species'' with adverse effects on humans, either directly (e.g. ''species'' that produce toxins that are harmful to humans) or indirectly (e.g. ''species'' that infest nature reserves) (Colautti and MacIsaac 2004).
;Biological control or biocontrol (See Biological pest control)
:# In general, the control of the numbers of one organism as a result of natural predation by another or others. Specifically, the human use of natural predators for the control of ''pests'' or ''weeds''. Also applied to the introduction of large numbers of sterilized males of the ''pest species'', whose matings result in the laying of infertile eggs (Allaby 1998).
:# The release of one ''species'' to control another (Carlton 2001).
:# The management of ''weeds'' using introduced herbivores (often insects) as biological control agents (Booth ''et al.'' 2003).
; Biological invasion or bioinvasion
: A broad term for both human-assisted introductions and natural range expansions (Carlton 2001).
;Biological diversity (See biodiversity)
: Used to describe ''species'' richness, ecosystem complexity, and genetic variation (Allaby 1998).
;Biological control (See Biological pest control)
: Control method involving a biological control agent that is a natural enemy of a target ''pest'' (Heutte and Bella 2003).
;Bioregion (See Ecoregion)
: A biological subdivision of the earth's surface delineated by the ''flora'' and ''fauna'' of the region (Allaby 1998).
; Biota
: The organisms (plants, animals, fungi, bacteria, algae, etc.) of a specific region or period, or the total aggregation of organisms in the biosphere (Allaby 1998).
; Casual species
: This term is becoming less common in usage. A ''non native species'' that does not form self-replacing ''populations'' (Booth ''et al.'' 2003). Similar terms include ''introduced species'', ''non indigenous species'', and ''non native species''.
; Chemical control
: Control method that employs herbicides to control ''exotic'' plants (Heutte and Bella 2003).
;Community
: Any grouping of ''populations'' of different organisms that live together in a particular environment (Allaby 1998).
; Cryptogenic species
: ''Species'' that are neither clearly ''native'' nor ''exotic'' (Cohen and Carlton 1988).
;Cultivar: A variety of a plant produced and maintained by horticultural techniques and not normally found in wild ''populations'' (Allaby 1998).
; Disturbance: An event or change in the environment that alters the composition and successional status of a biological community and may deflect succession onto a new trajectory, such as a forest fire or hurricane, glaciation, agriculture, and urbanization (Art 1993).
;Ecosystem: A discrete unit, or community of organisms and their physical environment (living and non-living parts), that interact to form a stable system (Allaby 1998).
;Endemic: A ''species'' or taxonomic group that is restricted to a particular geographic region because of such factors as isolation or response to soil or climatic conditions; this ''species'' is said to be endemic to the region (Allaby 1998).
;Exotic species (See Introduced species)
: This term is commonly used in publications and literature, and is similar to the terms ''alien species'', ''foreign species'', ''introduced species'', ''non indigenous species'', and ''non native species'' (Heutte and Bella 2003). Other definitions include:
:# An ''introduced'', ''non native species'', or a ''species'' that is the result of direct or indirect, deliberate or accidental introduction of the ''species'' by humans, and for which introduction permitted the species to cross a natural barrier to dispersal (Noss and Cooperrider 1994).
:# In North America, often refers to those ''species'' not present in a ''bioregion'' before the entry of Europeans in the 16th century, or present in later parts of that region and later introduced to an ecosystem by human-mediated mechanisms (Cohen and Carlton 1988).
;Fauna: The animal life of a region or geological period (Allaby 1998).
;Foreign species (See Introduced species): A species introduced to a new area or country. Similar terms include ''alien species'', ''exotic species'', ''introduced species'', ''non indigenous species'', and ''non native species''.
;Flora: Plant or bacterial life forms of a region or geological period (Allaby 1998).
;Habitat: The place, including physical and biotic conditions, where a plant or an animal usually occurs (Allaby 1998).
;Herbicide: ''Pesticide'' that specifically targets vegetation (Heutte and Bella 2003).
; Hybridization: Production of novel genotypes, through mating between distinct species or ecotypes. Novel genotypes may be more invasive than parental genotypes.
;Indigenous (See Indigenous species): A ''species'' that occurs naturally in an area; a synonym for ''native species'' (Allaby 1998).
; Injurious species: An ''introduced species'' that causes economic or environmental harm to humans. Similar terms include ''aquatic nuisance species'', ''noxious weed'', and ''invasive species'' (Heutte and Bella 2003).
; Intentional introduction: A ''species'' that is brought to a new area, country, or bioregion for a specific purpose, such as for a garden or lawn; a crop species; a landscaping ''species''; a ''species'' that provides food; a groundcover ''species''; for soil stabilization or hydrological control; for aesthetics or familiarity of the ''species''; or other purposeful reasons (Booth ''et al.'' 2003).
;Introduced species: This term, along with the terms ''introduced species'' and ''nonindigenous species'', is one of the most commonly used terms to describe a plant or animal species that is not originally from the area in which it occurs. This terms means those ''species'' that have been transported by human activities, either intentionally or unintentionally, into a region in which they did not occur in historical time and are now reproducing in the wild (Carlton 2001). Similar terms include ''alien species'', ''exotic species'', ''foreign species'', ''non indigenous specie''s, and ''non native species''.
; Invasibility: The ease with which a ''habitat'' is invaded (Booth ''et al.'' 2003).
;Invasion (See Introduced species and Invasive species): The expansion of a ''species'' into an area not previously occupied by it (Booth ''et al.'' 2003).
;Invasive species: Generally, this term refers to a subset of plants or animals that are introduced to an area, survive, and reproduce, and expand beyond the original area of introduction. This is the biological definition. Practical definitions add that they cause harm economically or environmentally within the new area of introduction.
:# An ''alien species'' whose introduction does or is likely to cause economic or environmental harm or harm to human health (Executive Order 1999).
:# An adjective for ''non native'' or ''nonindigenous species'' that have colonized natural areas;
:# Discrimination of ''nonindigenous species'' established in cultivated ''habitats'' (as 'noninvasive') from those established in natural ''habitats'';
:# ''Nonindigenous species'' that are widespread; or 5. Widespread ''nonindigenous species'' that have adverse effects on the invaded ''habitat'' (Colautti and MacIsaac 2004).
:Other definitions include the following:
;Integrated pest management: IPM focuses on long-term prevention or suppression of ''pests''. The integrated approach to ''weed'' management incorporates the best suited cultural, biological and chemical controls that have minimum impact on the environment and on people (Heutte and Bella 2003).
; Manual control: Removal that involves the use of tools such as shovels, axes, rakes, grubbing hoes, and hand clippers to expose, cut, and remove flowers, fruits, stems, leaves, and/or roots from target plants (Heutte and Bella 2003).
; Mechanical control: Removal that involves the use of motorized equipment such as mowers, "weed-whackers", and tractor-mounted plows, disks, and sweepers. Burning is also categorized here (Heutte and Bella 2003).
; Native range: The ecosystem that a ''species'' inhabits (Booth ''et al.'' 2003).
;Native species (See Indigenous (ecology)):
:# A synonym for ''indigenous species''
:# A ''species'' that occurs naturally in an area, and has not been introduced by humans either intentionally or unintentionally (Allaby 2005).
:# In North America, a ''species'' established before the year 500 (Jeschke and Strayer 2005)
; Native weed ( invasive native): A ''species'' that is native to an area or ''bioregion'' that has increased in number dramatically. In cases of ''disturbance'' or change to a landscape, a ''ruderal species'' can increase in cover and compete with other native plants, threatening the diversity of a community. In other cases, landscape level changes can cause the increase of the ''population'' of a ''species'', such as white-tailed deer in the northeastern part of the United States, which are at the highest levels historically and cause damage to humans, crops, and structures, suffer high disease levels, and pose threats to humans through interactions on roads (Foster and Sandberg 2004).
;Naturalized species (See Introduced species):
:# A ''species'' that was originally introduced from a different country, a different ''bioregion'', or a different geographical area, but now behaves like a native species in that it maintains itself without further human intervention and now grows and reproduces in native communities (Allaby 1998).
:# A ''non native species'' that forms self-sustaining ''populations'' but is not necessarily an ''invasive species'' (Booth ''et al.'' 2003).
;Neobiota: An umbrella term for the entirety of all non-native species, independently of their taxonomic rank, naturalization status or time of introduction, without defining these by a negation (non-native) or by an evaluative approach (Kowarik 2002.
; Niche opportunity: Defines conditions that promote invasions in terms of resources, natural enemies, the physical environment, interactions between these factors, and the manner in which they vary in time and space (Shea and Chesson 2002).
; Nonindigenous species: This is a common term used along with ''non native species'' and ''introduced species'' in current literature and publications; other similar terms include ''alien species'', ''exotic species'', and ''foreign species''.
:# Any ''species'' or other viable biological material that enters an ecosystem beyond its historic range, including any such organism transferred from one country into another (EPA 1990).
:# A plant or animal that is not native to the area in which it occurs which was either intentionally or unintentionally introduced (Williams and Meffe 2005).
; Non native species: This term, along with the terms ''introduced species'' and ''nonindigenous species'', is one of the most commonly used terms to describe a plant or animal ''species'' that is not originally from the area in which it occurs. Similar terms also include ''alien species'', ''exotic species'', and ''foreign species''. This term has also been defined as:
:# A ''species'' whose presence is due to ''intentional'' or ''unintentional introduction'' as a result of human activity (Booth ''et al.'' 2003).
:# A ''species'' that has been introduced to an area or ''bioregion'' (Heutte and Bella 2003).
;Noxious weed: This term is frequently a legal term in state code, denoting a special status of the plant as, for example, ''prohibited'' or ''restricted''.
:# Native or non-native plants, or plant products, that injure or cause damage to interests of agriculture, irrigation, navigation, natural resources, public health, or the environment (Heutte and Bella 2003).
:# Implies a ''species adverse effects on humans, either directly (e.g. ''species'' that produce toxins that are harmful to humans) or indirectly (e.g. species that infest nature reserves) (Colautti and MacIsaac 2004).
:# Any ''species'' of plants, either annual, biennial, or perennial; reproduced by seed, root, underground stem, or bulblet; which when established is or may become destructive and difficult to control by ordinary means of cultivation or other farm practices (Heutte and Bella 2003).
;Pathway (See Path):
:# Used to mean ''vector'', purpose (the reason why a ''species'' is moved), and route (the geographic corridor from one point to another) (Carlton 2001). 2. Mode by which a ''species'' establishes and continues to exist in a new environment (Heutte and Bella 2003).
; Pest:
:# An animal that competes with humans by consuming or damaging food, fiber, or other materials intended for human consumption or use, such as an insect consuming a cropfield (Allaby 1998)
:# Synonymous to ''invasive species'' (Jeschke and Strayer 2005).
;Pesticide: A chemical or biological agent intended to prevent, destroy, repel, or mitigate plant or animal life and any substance intended for use as a plant regulator, defoliant, or desiccant, including insecticides, fungicides, rodenticides, herbicides, nematocides, and biocides (Heutte and Bella 2003).
;Population: A group of potentially inter-breeding individuals of the same ''species'' found in the same place at the same time (Booth ''et al.'' 2003).
; Prohibited weed: A specific legal term applied to a plant or plant part that may not be brought into a state (Heutte and Bella 2003).
; Restricted weed: A specific legal term applied to a plant or plant part that may only be brought into a state in limited quantities (Heutte and Bella 2003).
; Ruderal species: A plant associated with human dwellings, construction, or agriculture, that usually colonizes disturbed or waste ground. Ruderals are often ''weeds'' which have high demands for nutrients and are intolerant of competition. See also ''native weed or invasive native'' (Allaby 1998).
; Seed bank: Seeds that become incorporated into the soil (Booth ''et al.'' 2003).
;Species: A group of organisms formally recognized as distinct from other groups; the taxon rank in the hierarchy of biological classification below genus; the basic unit of biological classification, defined by the reproductive isolation of the group from all other groups of organisms (Allaby 1998).
; Tens rule
:# Describes how approximately ten percent of ''species'' pass through each transition from being imported to becoming ''casual'' to becoming established, and finally becoming a ''weed'' (Booth ''et al.'' 2003).
:# Ten percent of the ''introduced species'' establish themselves in the non native continent and ten percent of these, in turn, spread or are ''pests'' although many exceptions to this rule have been noted (Jeschke and Strayer 2005).
;Time lag
:# Time between introduction, establishment, and spread of a ''species'' (Jeschke and Strayer 2005).
:# The time between when a ''species'' is introduced and when its ''population'' growth explodes (Booth ''et al.'' 2003).
; Unintentional introduction: An introduction of ''nonindigenous species'' that occurs as the result of activities other than the purposeful or intentional introduction of the ''species'' involved, such as the transport of ''nonindigenous species'' in ballast or in water used to transport fish, mollusks or crustaceans for aquaculture or other purposes (EPA 1990).
;Vector (See Vector (epidemiology)): The physical means or agent by which a ''species'' is transported, such as ballast water, ships' hulls, boats, hiking boats, cars, vehicles, packing material, or soil in nursery stock (Carlton 2001). See also ''pathway''.
;Weed:
:# A plant in the wrong place, being one that occurs opportunistically on land or in water that has been disturbed by human activities (see also ''ruderal species'' and ''native weed or invasive native''), or on cultivated land, where it competes for nutrients, water, sunlight, or other resources with cultivated plants such as food crops. Under different circumstances the weed plant itself may be cultivated for different purposes (Allaby 1998).
:# A ''native'' or ''introduced species'' that has a perceived negative ecological or economic effect on agricultural or natural ecosystems (Booth ''et al.'' 2003).
:# A plant growing in an area where it is not wanted (Royer and Dickinson 1999).

Legal definitions

; Invasive species (United States)
: Executive Order 13112 (1999) defines this term as an ''alien species'' whose introduction does or is likely to cause economic or environmental harm or harm to human health. Website

; Introduction (United States)
: Executive Order 13112 (1999) defines this term as the intentional or unintentional escape, release, dissemination, or placement of a ''species'' into an ecosystem as a result of human activity. Website

; Native species (United States)
: Executive Order 13112 (1999) defines this term as a ''species'' with respect to a particular ecosystem that historically occurred or currently occurs in that ecosystem rather than as a result of an introduction. Website

; Nonindigenous species (United States)
: The Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990 (Public Law 101-646, 16 USC 4701-4741) defines this term as any ''species'' or other viable biological material that enters an ecosystem beyond its historic range, including any such organism transferred from one country into another. ebsite: http://www.epa.gov/owow/invasive_species/nanpca90.pdf; Species (United States)
: Executive Order 13112 (1999) defines this term as a group of organisms, all of which have a high degree of physical and genetic similarity, generally interbreed only among themselves, and show persistent differences from members of allied groups of organisms. Website

; Unintentional introduction (United States)
: The Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990 (Public Law 101-646, 16 USC 4701-4741) defines this term as an introduction of ''nonindigenous species'' that occurs as the result of activities other than the purposeful or intentional introduction of the ''species'' involved, such as the transport of ''nonindigenous species'' in ballast or in water used to transport fish, mollusks or crustaceans for aquaculture or other purposes. Website

See also

* Neophyte (botany), Neophyte
* Archaeophyte
*Columbian Exchange

References

*Allaby, M. 1998. Oxford Dictionary of Ecology. New York, NY: Oxford University Press.
*Art, H. W. 1993. The Dictionary of Ecology and Environmental Science. New York, NY: Henry Holt and Company.
*Booth, B. D., S. D. Murphy, and C. J. Swanton. 2003. Weed Ecology in Natural and Agricultural Systems. Cambridge, MA: CABI Publishing.
*Carlton, J.T. 2001. Introduced Species in U.S. Coastal Waters: Pew Oceans Commissions Report. Pew Oceans Commissions: Washington, DC.
*Clearwater S.J., Hickey C.W. & Martin M.L. 2008. Overview of potential piscicides and molluscicides for controlling aquatic pest species in New Zealand. ''Science for Conservation 283''. p 74. Published by Department of Conservation, New Zealand


*Cohen, A. H., and J. T. Carlton. 1998. Accelerating invasion rate in a highly invaded estuary. Science 279: 555–58.
*Colautti, R. I., and H. J. MacIsaac. 2004. A neutral terminology to define 'invasive' species. Diversity and Distributions 10: 134–41.
*Executive Presidential Order. 1999. Executive Order 13112 of February 3, 1999: Invasive Species. Federal Register 64 (25):6183-6186.
*Foster, J., and L. A. Sandberg. 2004. Friends or foe? Invasive species and public green space in Toronto. The Geographical Review 94(2): 178–98.
*Helmreich, S. 2005. How scientists think; about 'natives', for example. A problem of taxonomy among biologists of alien species in Hawaii. Journal of the Royal Anthropological Institute 11:107-28.
*Heutte, T., and E. Bella. 2003. Invasive plants and exotic weeds of Southeast Alaska. Anchorage, AK: USDA Forest Service. Website

*Jeschke, J. M., and D. L. Strayer. 2005. Invasion success of vertebrates in Europe and North America. Proceedings of the National Academy of Sciences 102(20):7198-202.
*Kowarik, I. 2002. Biologische Invasionen in Deutschland: zur Rolle nichteinheimischer Pflanzen. NeoBiota 1:5-24.
*Larson, B. M. H. 2005. The war of the roses: demilitarizing invasion biology. Frontiers in Ecology and the Environment 3(9):495-500.
*Noss, R. F., and A. Y. Cooperrider. 1994. Saving Nature's Legacy: Protecting and Restoring Biodiversity. Washington, DC: Island Press.
*Robbins, P. 2005. Comparing invasive networks: cultural and political biographies of invasive species. The Geographical Review 94(20):139-56.
*Royer, F., and R. Dickinson. 1999. Weeds of the northern U.S. and Canada. Edmonton, AB: Lone Pine Press.
*Shea, K., and P. Chesson. 2002. Community ecology theory as a framework for biological invasions. Trends in Ecology and the Environment 17(4):170-176.
*Shrader-Frechette, K. 2001. Non-indigenous species and ecological explanation. Biology and Philosophy 16:507-19.
*United States Environmental Protection Agency (EPA). 1990. Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990. Washington, DC.
*Vermeij, G. J. 2005. Invasion as Expectation: A historical fact of life. Pages 315–339 in D. F. Sax, J. J. Stachowicz, and S. D. Gaines, editors. Species invasions: insights into ecology, evolution and biogeography. Sinauer Associates, Inc., Sunderland, MA.
*Williams, J. D., and G. K. Meffe. 2005. Status and trends of the nation's biological resources: Nonindigenous species. Washington, DC: US Geological Survey.
*Woods, M., and P. V. Moriarty. 2001. Strangers in a strange land: The problem of exotic species. Environmental Values 10:163-91.

External links

Global Invasive Species DatabaseGlobal Invasive Species Programme (GISP)The Nature Conservancy Global Invasive Species InitiativeUnion of Concerned Scientists Invasive Species

;Africa
Forest Invasive Species Network for Africa – FISNADST-NRF Centre of Excellence for Invasion Biology

;Australia and New Zealand
Australian Government Department of Climate Change, Energy, the Environment and Water, Invasive Species pageCSIRO Australian WeedsQueensland Government Weeds & Pest Animal ManagementTasmanian Government Pests and DiseasesBiosecurity New Zealand

;Europe
Regional Biological Invasions Centre (Europe)

NEOBIOTA - The European Group on Biological Invasions

;United States (including Hawaii)
Hawaiian Ecosystems at Risk project (HEAR)
{{Webarchive, url=https://web.archive.org/web/20210221021637/http://www.hear.org/ , date=2021-02-21
United States Executive Order 13112 (1999)United States Federal Interagency Committee for the Management of Noxious and Exotic Weeds (FICMNEW)United States Invasive Species Government site (Invasivespecies.gov)United States Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990Weed Science Society of America

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