Naturalization and invasion of alien plants: concepts and definitions
TL;DR: It is proposed that the term ‘invasive’ should be used without any inference to environmental or economic impact, and terms like ‘pests’ and ‘weeds’ are suitable labels for the 50–80% of invaders that have harmful effects.
Abstract: . Much confusion exists in the English-language literature on plant invasions concerning the terms ‘naturalized’ and ‘invasive’ and their associated concepts. Several authors have used these terms in proposing schemes for conceptualizing the sequence of events from introduction to invasion, but often imprecisely, erroneously or in contradictory ways. This greatly complicates the formulation of robust generalizations in invasion ecology.
Based on an extensive and critical survey of the literature we defined a minimum set of key terms related to a graphic scheme which conceptualizes the naturalization/invasion process. Introduction means that the plant (or its propagule) has been transported by humans across a major geographical barrier. Naturalization starts when abiotic and biotic barriers to survival are surmounted and when various barriers to regular reproduction are overcome. Invasion further requires that introduced plants produce reproductive offspring in areas distant from sites of introduction (approximate scales: > 100 m over 6 m/3 years for taxa spreading by roots, rhizomes, stolons or creeping stems). Taxa that can cope with the abiotic environment and biota in the general area may invade disturbed, seminatural communities. Invasion of successionally mature, undisturbed communities usually requires that the alien taxon overcomes a different category of barriers.
We propose that the term ‘invasive’ should be used without any inference to environmental or economic impact. Terms like ‘pests’ and ‘weeds’ are suitable labels for the 50–80% of invaders that have harmful effects. About 10% of invasive plants that change the character, condition, form, or nature of ecosystems over substantial areas may be termed ‘transformers’.
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TL;DR: Although restricted to few taxa, these studies reveal clear relationships between the characteristics of releases and the species involved, and the successful establishment and spread of invaders.
Abstract: Predicting which species are probable invaders has been a long-standing goal of ecologists, but only recently have quantitative methods been used to achieve such a goal. Although restricted to few taxa, these studies reveal clear relationships between the characteristics of releases and the species involved, and the successful establishment and spread of invaders. For example, the probability of bird establishment increases with the number of individuals released and the number of release events. Also, the probability of plant invasiveness increases if the species has a history of invasion and reproduces vegetatively. These promising quantitative approaches should be more widely applied to allow us to predict patterns of invading species more successfully.
2,698 citations
TL;DR: A unified framework for biological invasions is proposed that reconciles and integrates the key features of the most commonly used invasion frameworks into a single conceptual model that can be applied to all human-mediated invasions.
Abstract: There has been a dramatic growth in research on biological invasions over the past 20 years, but a mature understanding of the field has been hampered because invasion biologists concerned with different taxa and different environments have largely adopted different model frameworks for the invasion process, resulting in a confusing range of concepts, terms and definitions. In this review, we propose a unified framework for biological invasions that reconciles and integrates the key features of the most commonly used invasion frameworks into a single conceptual model that can be applied to all human-mediated invasions. The unified framework combines previous stage-based and barrier models, and provides a terminology and categorisation for populations at different points in the invasion process.
1,795 citations
TL;DR: A multiphase model describing the interrelationships between plant invaders and fire regimes is presented, a system for evaluating the relative effects of invaders and prioritizing them for control is provided, and ways to restore pre-invasion fire regime properties are recommended.
Abstract: Plant invasions are widely recognized as significant threats to biodiversity conservation worldwide. One way invasions can affect native ecosystems is by changing fuel properties, which can in turn affect fire behavior and, ultimately, alter fire regime characteristics such as frequency, intensity, extent, type, and seasonality of fire. If the regime changes subsequently promote the dominance of the invaders, then an invasive plant–fire regime cycle can be established. As more ecosystem components and interactions are altered, restoration of preinvasion conditions becomes more difficult. Restoration may require managing fuel conditions, fire regimes, native plant communities, and other ecosystem properties in addition to the invaders that caused the changes in the first place. We present a multiphase model describing the interrelationships between plant invaders and fire regimes, provide a system for evaluating the relative effects of invaders and prioritizing them for control, and recommend ways...
1,440 citations
Cites background from "Naturalization and invasion of alie..."
...Species that can overcome these dispersal and environmental barriers become invasive (sensu Richardson et al. 2000)....
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...They can also indirectly affect native plants and change ecosystems by altering soil stability; promoting erosion; colonizing open substrates; affecting the accumulation of litter, salt, or other soil resources; and promoting or suppressing fire (Vitousek 1990, Richardson et al. 2000)....
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...The second phase of the cycle is the introduction of propagules into a new region, which requires the invader species to overcome significant geographical barriers to dispersal (Richardson et al. 2000)....
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TL;DR: Elton's "The Ecology of Invasions by Animals and Plants" as mentioned in this paper is one of the most cited books on invasion biology, and it provides an accessible, engaging introduction to the most important environmental crises of our time.
Abstract: Much as Rachel Carson's \"Silent Spring\" was a call to action against the pesticides that were devastating bird populations, Charles S. Elton's classic \"The Ecology of Invasions by Animals and Plants\" sounded an early warning about an environmental catastrophe that has become all too familiar today-the invasion of nonnative species. From kudzu to zebra mussels to Asian long-horned beetles, nonnative species are colonizing new habitats around the world at an alarming rate thanks to accidental and intentional human intervention. One of the leading causes of extinctions of native animals and plants, invasive species also wreak severe economic havoc, causing $79 billion worth of damage in the United States alone. Elton explains the devastating effects that invasive species can have on local ecosystems in clear, concise language and with numerous examples. The first book on invasion biology, and still the most cited, Elton's masterpiece provides an accessible, engaging introduction to one of the most important environmental crises of our time. Charles S. Elton was one of the founders of ecology, who also established and led Oxford University's Bureau of Animal Population. His work has influenced generations of ecologists and zoologists, and his publications remain central to the literature in modern biology. \"History has caught up with Charles Elton's foresight, and \"The Ecology of Invasions\" can now be seen as one of the central scientific books of our century.\"-David Quammen, from the Foreword to \"Killer Algae: The True Tale of a Biological Invasion\
1,321 citations
TL;DR: Recommendations are outlined on how to deal with the issue of plant invasions in standard floras with the aim of contributing to a better understanding between taxonomists and ecologists and allowing more detailed comparative analyses of alien floras of various regions of the world.
Abstract: The number of studies dealing with plant invasions is increasing rapidly, but the accumulating body of knowledge has unfortunately also spawned increasing confusion about terminology. Invasions are a global phenomenon and comparison of geographically distant regions and their introduced biota is a crucially important methodological approach for elucidation of the determinants of invasiveness and invasibility. Comparative studies of alien floras provide substantial new insights to our understanding of general patterns of plant invasions. Such studies, using information in previously published floras and checklists, are fundamentally dependent on the quality of the assessment of particular species with respect to their taxonomic identity, time of immigration and invasion status. Three crucial decisions should be made when defining the status of a plant species in a given region: (1) whether the taxon is native or alien to that region (origin status); (2) what is its position in the invasion process, i.e., when was it introduced (residence status); and (3) what is the degree of its naturalization and possible invasion (invasion status). Standard floras differ hugely in their treatment of non-native species and those with appropriate categorization of alien species according to their status are rather rare. The present paper suggests definitions of terms associated with plant invasions and places these into the context of floras. Recommendations are outlined on how to deal with the issue of plant invasions in standard floras with the aim of contributing to a better understanding between taxonomists and ecologists and allowing more detailed comparative analyses of alien floras of various regions of the world.
1,283 citations
References
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Book•
03 Sep 2009
TL;DR: The "Penguin Classics" edition of "On the Origin of Species" as discussed by the authors contains an introduction and notes by William Bynum, and features a cover designed by Damien Hirst.
Abstract: Charles Darwin's seminal formulation of the theory of evolution, "On the Origin of Species" continues to be as controversial today as when it was first published. This "Penguin Classics" edition contains an introduction and notes by William Bynum, and features a cover designed by Damien Hirst. Written for a general readership, "On the Origin of Species" sold out on the day of its publication and has remained in print ever since. Instantly and persistently controversial, the concept of natural selection transformed scientific analysis about all life on Earth. Before the "Origin of Species", accepted thinking held that life was the static and perfect creation of God. By a single, systematic argument Darwin called this view into question. His ideas have affected public perception of everything from religion to economics. William Bynum's introduction discusses Darwin's life, the publication and reception of the themes of "On the Origin of Species", and the subsequent development of its major themes. The new edition also includes brief biographies of some of the most important scientific thinkers leading up to and surrounding the "Origin of Species", suggested further reading, notes and a chronology. Charles Darwin (1809-82), a Victorian scientist and naturalist, has become one of the most famous figures of science to date. The advent of "On the Origin of Species" by means of natural selection in 1859 challenged and contradicted all contemporary biological and religious beliefs. If you enjoyed "On the Origin of Species", you might like Darwin's "The Descent of Man", also available in "Penguin Classics".
7,487 citations
4,002 citations
TL;DR: It is concluded that the elusive nature of the invasion process arises from the fact that it depends upon conditions of resource enrichment or release that occur only intermittently and, to result in invasion, must coincide with availability of invading propagules.
Abstract: Summary
1 The invasion of habitats by non-native plant and animal species is a global phenomenon with potentially grave consequences for ecological, economic, and social systems. Unfortunately, to date, the study of invasions has been primarily anecdotal and resistant to generalization.
2 Here, we use insights from experiments and from long-term monitoring studies of vegetation to propose a new theory in which fluctuation in resource availability is identified as the key factor controlling invasibility, the susceptibility of an environment to invasion by non-resident species. The theory is mechanistic and quantitative in nature leading to a variety of testable predictions.
3 We conclude that the elusive nature of the invasion process arises from the fact that it depends upon conditions of resource enrichment or release that have a variety of causes but which occur only intermittently and, to result in invasion, must coincide with availability of invading propagules.
3,169 citations
"Naturalization and invasion of alie..." refers background in this paper
...There are certainly many opportunities for integrating insights from invasion ecology with those from research on local vegetation dynamics (Rejmánek, 1989; Vitousek, 1990; Richardson & Bond, 1991; Davis et al., 2000)....
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Book•
06 Jan 2012
TL;DR: The first book on invasion biology, and still the most cited, Elton's masterpiece provides an accessible, engaging introduction to one of the most important environmental crises of the authors' time.
Abstract: Much as Rachel Carson's "Silent Spring" was a call to action against the pesticides that were devastating bird populations, Charles S. Elton's classic "The Ecology of Invasions by Animals and Plants" sounded an early warning about an environmental catastrophe that has become all too familiar today-the invasion of nonnative species. From kudzu to zebra mussels to Asian long-horned beetles, nonnative species are colonizing new habitats around the world at an alarming rate thanks to accidental and intentional human intervention. One of the leading causes of extinctions of native animals and plants, invasive species also wreak severe economic havoc, causing $79 billion worth of damage in the United States alone. Elton explains the devastating effects that invasive species can have on local ecosystems in clear, concise language and with numerous examples. The first book on invasion biology, and still the most cited, Elton's masterpiece provides an accessible, engaging introduction to one of the most important environmental crises of our time. Charles S. Elton was one of the founders of ecology, who also established and led Oxford University's Bureau of Animal Population. His work has influenced generations of ecologists and zoologists, and his publications remain central to the literature in modern biology. "History has caught up with Charles Elton's foresight, and "The Ecology of Invasions" can now be seen as one of the central scientific books of our century."-David Quammen, from the Foreword to "Killer Algae: The True Tale of a Biological Invasion"
2,530 citations
TL;DR: The history of biology describes the rise of science from the seventeenth century to the twentieth century and the changing intellectual milieu of biology.
2,360 citations
"Naturalization and invasion of alie..." refers background in this paper
...One reason for the complicated classification schemes used in Central Europe may be the strong ‘classificatory’ tradition in this part of the world (see, e.g. Mayr, 1982; Jahn, 1998)....
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