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Bernd Blossey

Bio: Bernd Blossey is an academic researcher from Cornell University. The author has contributed to research in topics: Lythrum salicaria & Introduced species. The author has an hindex of 42, co-authored 128 publications receiving 7681 citations. Previous affiliations of Bernd Blossey include International Institute of Minnesota & University of Kiel.


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TL;DR: There are very few valid generalizations about invasive species, so that it is only possible to make weak, probabilistic predictions about which species will invade (Gilpin 1990; Daehler & Strong 1993).
Abstract: There are very few valid generalizations about invasive species, so that it is only possible to make weak, probabilistic predictions about which species will invade (Gilpin 1990; Daehler & Strong 1993). A phenomenon that has not received much attention, however, is the observation that, in alien environments, plants tend to be more vigorous and taller, producing more seeds than in their native distribution (Crawley 1987). The seed production of Chrysanthemoides monilifera (native to Sout'l Africa) in Australia and of Acacia longifolia (native to Australia) in South Africa is an order of magnitude higher where the plants are aliens (Noble 1989). The vigour and success of aliens in areas where they have been introduced has been attributed to both, more favourable environments, and to the release from natural phytophagous enemies (Crawley 1987). These alternatives can be evaluated according to two theories relating to resource allocation. The optimal defence hypothesis predicts that plants with limited resources will show trade-offs in biomass allocation among maintenance, growth, storage, reproduction, and defence (Coley et al. 1985; Bazzaz et al. 1987; Fagerstrom 1989; Herms & Mattson 1994; Lerdau et al. 1995). The environmental constraint hypothesis (Bryant et al. 1988), however, predicts that the evolution of defence mechanisms against herbivory will result in only minor reductions in growth. Resource availability is then the primary force determining whether there is surplus photosynthate available for allocation to secondary metabolism.

1,708 citations

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TL;DR: In this article, the global distribution and context (protected status, biome, anthrome, and net primary productivity) of 2573 terrestrial study sites reported in recent publications (2004-2009) of 10 highly cited ecology journals were analyzed.
Abstract: Although the geographical context of ecological observations shapes ecological theory, the global distribution of ecological studies has never been analyzed. Here, we document the global distribution and context (protected status, biome, anthrome, and net primary productivity) of 2573 terrestrial study sites reported in recent publications (2004–2009) of 10 highly cited ecology journals. We find evidence of several geographical biases, including overrepresentation of protected areas, temperate deciduous woodlands, and wealthy countries. Even within densely settled or agricultural regions, ecologists tend to study “natural” fragments. Such biases in trendsetting journals may limit the scalability of ecological theory and hinder conservation efforts in the 75% of the terrestrial world where humans live and work.

402 citations

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TL;DR: In later successional habitats, root feeders appear to be the more potent force in driving plant performance and plant community composition and their importance in natural areas, particularly in the tropics.
Abstract: Investigations of plant-herbivore interactions continue to be popular; however, a bias neglecting root feeders may limit our ability to understand how herbivores shape plant life histories. Root feeders can cause dramatic plant population declines, often associated with secondary stress factors such as drought or grazing. These severe impacts resulted in substantial interest in root feeders as agricultural pests and increasingly as biological weed control agents, particularly in North America. Despite logistical difficulties, establishment rates in biocontrol programs are equal or exceed those of aboveground herbivores (67.2% for aboveground herbivores, 77.5% for belowground herbivores) and root feeders are more likely to contribute to control (53.7% versus 33.6%). Models predicting root feeders would be negatively affected by competitively superior aboveground herbivores may be limited to early successional habitats or generalist root feeders attacking annual plants. In later successional habitats, root feeders become more abundant and appear to be the more potent force in driving plant performance and plant community composition. Aboveground herbivores, even at high population levels, were unable to prevent buildup of root herbivore populations and the resulting population collapse of their host plants. Significant information gaps exist about the impact of root feeders on plant physiology and secondary chemistry and their importance in natural areas, particularly in the tropics.

329 citations

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TL;DR: The evolutionary trap concept provides a useful framework for predicting and managing the impact of harmful invasive species and is proposed to promote the long-term co-existence of native and introduced species in cases where the eradication of the latter is either economically or biologically unrealistic.
Abstract: Invasive species can alter environments in such a way that normal behavioural decision-making rules of native species are no longer adaptive. The evolutionary trap concept provides a useful framework for predicting and managing the impact of harmful invasive species. We discuss how native species can respond to changes in their selective regime via evolution or learning. We also propose novel management strategies to promote the long-term co-existence of native and introduced species in cases where the eradication of the latter is either economically or biologically unrealistic.

303 citations


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6,278 citations

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TL;DR: About 42% of the species on the Threatened or Endangered species lists are at risk primarily because of alien-invasive species.

4,463 citations

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TL;DR: In this article, the introduction of invasive species and identifying life history stages where management will be most effective are discussed. And evolutionary processes may be key features in determining whether invasive species establish and spread.
Abstract: ■ Abstract Contributions from the field of population biology hold promise for understanding and managing invasiveness; invasive species also offer excellent opportunities to study basic processes in population biology. Life history studies and demographic models may be valuable for examining the introduction of invasive species and identifying life history stages where management will be most effective. Evolutionary processes may be key features in determining whether invasive species establish and spread. Studies of genetic diversity and evolutionary changes should be useful for

3,280 citations

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TL;DR: Competitive release through greater generalist enemy impact on natives seems to be an important but understudied mechanism of enemy release, but there is a serious need for experiments involving exclusion of natural enemies in invaded plant communities.
Abstract: To curb the future economic and environmental impacts of invasive exotic species, we need to understand the mechanisms behind exotic invasions. One commonly accepted mechanism for exotic plant invasions is the enemy release hypothesis (ERH), which states that plant species, on introduction to an exotic region, experience a decrease in regulation by herbivores and other natural enemies, resulting in a rapid increase in distribution and abundance. The success of classical biological control has been used as support for ERH, but this observational evidence does not directly test ERH, and the more experimental evidence is equivocal. Competitive release through greater generalist enemy impact on natives seems to be an important but understudied mechanism of enemy release, but there is a serious need for experiments involving exclusion of natural enemies in invaded plant communities. With a clearer understanding of the role of enemy release in exotic plant invasions, we can begin to build a comprehensive predictive model of exotic plant invasions.

3,173 citations

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TL;DR: Aproximately 50,000 nonindigenous (non-native) species are estimated to have been introduced to the United States, many of which are beneficial but have caused major economic losses in agriculture, forestry, and several other segments of the US economy, in addition to harming the environment.
Abstract: [Extract] Aproximately 50,000 nonindigenous (non-native) species are estimated to have been introduced to the United States. Some of these are beneficial; for example, species introduced as food crops (e.g., corn, wheat, and rice) and as livestock (e.g., cattle and poultry) now provide more than 98% of the US food system, at a value of approximately $800 billion per year (USBC 1998). Other exotic species have been introduced for landscape restoration, biological pest control, sport, pets, and food processing, also with significant benefits. Some nonindigenous species, however, have caused major economic losses in agriculture, forestry, and several other segments of the US economy, in addition to harming the environment. One study reported that 79 exotic species had caused approximately $97 billion in damages during the period 1906–1991 (OTA 1993).

2,922 citations