An assessment of the colonizing ability of <i>Emex australis</i>

Panetta, F. D.; Randall, R. P.

doi:10.1111/j.1442-9993.1994.tb01546.x

Cited by 6 publications

(6 citation statements)

References 14 publications

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“…Theoretical models (Lande 1988(Lande , 1993 and simulations (Lande and Orzack 1988;Menges 1991;Grevstad 1999b) indicate that extinction varies inversely to the size of the immigrant population. Our multi-year field results with multiple species strengthen these predictions and are also consistent with the results of other experimental plant introductions (Panetta and Randall 1994). The likelihood of persistence also rises as the number of introduction events increases (Simberloff 1989;Guerrant 1996;Veltman et al 1996;Grevstad 1999b).…”

Section: Mitigating Barriers To Persistencesupporting

confidence: 86%

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Naturalization of plant populations: the role of cultivation and population size and density

Minton

2010

Oecologia

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Field experimentation is required to assess the effects of environmental stochasticity on small immigrant plant populations-a widely understood but largely unexplored aspect of predicting any species' likelihood of naturalization and potential invasion. Cultivation can mitigate this stochasticity, although the outcome for a population under cultivation nevertheless varies enormously from extinction to persistence. Using factorial experiments, we investigated the effects of population size, density, and cultivation (irrigation) on the fate of founder populations for four alien species with different life history characteristics (Echinochloa frumentacea, Fagopyrum esculentum, Helianthus annuus, and Trifolium incarnatum) in eastern Washington, USA. The fate of founder populations was highly variable within and among the 3 years of experimentation and illustrates the often precarious environment encountered by plant immigrants. Larger founder populations produced more seeds (P < 0.001); the role of founder population size, however, differed among years. Irrigation resulted in higher percent survival (P < 0.001) and correspondingly larger net reproductive rate (R(0); P < 0.001). But the minimum level of irrigation for establishment, R(0) > 1, differed among years and species. Sowing density did not affect the likelihood of establishment for any species. Our results underscore the importance of environmental stochasticity in determining the fate of founder populations and the potential of cultivation and large population size in countering the long odds against naturalization. Any implementation of often proposed post-immigration field trials to assess the risk of an alien species becoming naturalized, a requisite step toward invasion, will need to assess different sizes of founder populations and the extent and character of cultivation (intentional or unintentional) that the immigrants might receive.

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Section: Mitigating Barriers To Persistencesupporting

confidence: 86%

“…Guerrant 1996). Similar low probabilities of establishment have been documented in experimental introductions of Melaleuca quinquenervia (Myers 1983), Emex australis (Panetta and Randall 1994), and Brassica napus (Crawley et al 1993) at sites well within these species' ecological amplitude.…”

Section: The Unpredictable Fate Of Foundersmentioning

confidence: 66%

Naturalization of plant populations: the role of cultivation and population size and density

Minton

2010

Oecologia

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“…Naturalization only starts when environmental barriers (B) do not prevent individuals from surviving and when various barriers to regular reproduction (C) are overcome. Therefore a taxon can be considered successfully naturalized after overcoming barriers A, B and C. At this stage populations are sufficiently large that the probability of extinction due to environmental stochasticity is low (MacArthur, 1972;Menges, 2000; see also Panetta & Randall, 1994 with regard to Emex australis ). Several authors have attempted to define the degree to which an alien taxon is naturalized.…”

Section: Towards a Standardized Terminology For Plant Invasion Ecologymentioning

confidence: 99%

Naturalization and invasion of alien plants: concepts and definitions

Richardson

Pyšek

Rejmánek

et al. 2000

Diversity and Distributions

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2,591

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“…Added to the uncertainty regarding the seed bank status of a targeted infestation is the demographic stochasticity associated with very small populations. While eradication sensu stricto is not achieved until no living trace of a weed remains, a weed infestation may become effectively moribund when seed banks reach very low densities, since it will become prone to stochastic extinction (Shaffer, 1981; Ehrlich, 1989), as it might have been during the colonization phase (Panetta & Randall, 1994). Since extirpation is an event that is determined probabilistically, it is difficult to define critical seed population levels — a population simply becomes more prone to extirpation as it becomes smaller.…”

Section: The Extirpation Criterionmentioning

confidence: 99%

Evaluation of weed eradication programs: containment and extirpation

Panetta¹

2006

Diversity and Distributions

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Weed eradication programs often require 10 years or more to achieve their objective. It is important that progress is evaluated on a regular basis so that programs that are 'on track' can be distinguished from those that are unlikely to succeed. Earlier research has addressed conformity of eradication programs to the delimitation criterion. In this paper evaluation in relation to the containment and extirpation criteria is considered. Because strong evidence of containment failure (i.e. spread from infestations targeted for eradication) is difficult to obtain, it generally will not be practicable to evaluate how effective eradication programs are at containing the target species. However, chronic failure of containment will be reflected in sustained increases in cumulative infested area and thus a failure to delimit a weed invasion. Evaluating the degree of conformity to the delimitation and extirpation criteria is therefore sufficient to give an appraisal of progress towards the eradication objective. A significant step towards eradication occurs when a weed is no longer readily detectable at an infested site, signalling entry to the monitoring phase. This transition will occur more quickly if reproduction is prevented consistently. Where an invasion consists of multiple infestations, the monitoring profile (frequency distribution of time since detection) provides a summary of the overall effectiveness of the eradication program in meeting the extirpation criterion. Eradication is generally claimed when the target species has not been detected for a period equal to or greater than its seed longevity, although there is often considerable uncertainty in estimates of the latter. Recently developed methods, which take into consideration the cost of continued monitoring vs. the potential cost of damage should a weed escape owing to premature cessation of an eradication program, can assist managers to decide when to terminate weed eradication programs.

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An assessment of the colonizing ability of Emex australis

Cited by 6 publications

References 14 publications

Naturalization of plant populations: the role of cultivation and population size and density

Naturalization of plant populations: the role of cultivation and population size and density

Naturalization and invasion of alien plants: concepts and definitions

Evaluation of weed eradication programs: containment and extirpation

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