Results 1 - 10
of
158
Ecological impacts of invasive alien plants: a meta-analysis of their effects on species, communities and ecosystems.
- Ecol. Lett.
, 2011
"... Abstract Biological invasions cause ecological and economic impacts across the globe. However, it is unclear whether there are strong patterns in terms of their major effects, how the vulnerability of different ecosystems varies and which ecosystem services are at greatest risk. We present a global ..."
Abstract
-
Cited by 52 (10 self)
- Add to MetaCart
(Show Context)
Abstract Biological invasions cause ecological and economic impacts across the globe. However, it is unclear whether there are strong patterns in terms of their major effects, how the vulnerability of different ecosystems varies and which ecosystem services are at greatest risk. We present a global meta-analysis of 199 articles reporting 1041 field studies that in total describe the impacts of 135 alien plant taxa on resident species, communities and ecosystems. Across studies, alien plants had a significant effect in 11 of 24 different types of impact assessed. The magnitude and direction of the impact varied both within and between different types of impact. On average, abundance and diversity of the resident species decreased in invaded sites, whereas primary production and several ecosystem processes were enhanced. While alien N-fixing species had greater impacts on N-cycling variables, they did not consistently affect other impact types. The magnitude of the impacts was not significantly different between island and mainland ecosystems. Overall, alien species impacts are heterogeneous and not unidirectional even within particular impact types. Our analysis also reveals that by the time changes in nutrient cycling are detected, major impacts on plant species and communities are likely to have already occurred.
Mammal invaders on islands: impact, control and control impact
- Biological Review
, 2003
"... The invasion of ecosystems by exotic species is currently viewed as one of themost important sources of biodiversity loss. The largest part of this loss occurs on islands, where indigenous species have often evolved in the absence of strong competition, herbivory, parasitism or predation. As a resul ..."
Abstract
-
Cited by 50 (2 self)
- Add to MetaCart
The invasion of ecosystems by exotic species is currently viewed as one of themost important sources of biodiversity loss. The largest part of this loss occurs on islands, where indigenous species have often evolved in the absence of strong competition, herbivory, parasitism or predation. As a result, introduced species thrive in those optimal insular ecosystems affecting their plant food, competitors or animal prey. As islands are characterised by a high rate of endemism, the impacted populations often correspond to local subspecies or even unique species. One of the most important taxa concerning biological invasions on islands is mammals. A small number of mammal species is responsible for most of the damage to invaded insular ecosystems: rats, cats, goats, rabbits, pigs and a few others. The effect of alien invasive species may be simple or very complex, especially since a large array of invasive species, mammals and others, can be present simultaneously and interact among themselves as well as with the indigenous species. In most cases, introduced species generally have a strong impact and they often are responsible for the impoverishment of the local flora and fauna. The best response to these effects is almost always to control the alien population, either by regularly reducing their numbers, or better still, by eradicating the population as a whole from the island. Several types of methods are currently used: physical ( trapping, shooting), chemical (poisoning) and biological (e.g. directed use of diseases). Each has its own set of advantages and disadvantages, depending on the
The economic consequences of alien plant invasions: examples of impacts and approaches to sustainable management
- Sustainability
, 2001
"... Abstract. The invasion of natural ecosystems by alien plants is a serious environmental problem that threatens the sustainable use of benefits derived from such ecosytems. Most past studies in this field have focussed on the history, ecology and management of invasive alien species, and little work ..."
Abstract
-
Cited by 23 (2 self)
- Add to MetaCart
Abstract. The invasion of natural ecosystems by alien plants is a serious environmental problem that threatens the sustainable use of benefits derived from such ecosytems. Most past studies in this field have focussed on the history, ecology and management of invasive alien species, and little work has been done on the economic aspects and consequences of invasions. This paper reviews what is known of the economic consequences of alien plant invasions in South Africa. These economic arguments have been used to successfully launch the largest environmental management programme in Africa. Ten million hectares of South Africa has been invaded by 180 alien species, but their impacts are not fully understood, although they are undoubtedly significant. The indications are that the total costs of these impacts are substantial. Selected studies show that invasions have reduced the value of fynbos ecosystems by over US $ 11.75 billion; that the total cost of invasion would be about US $ 3.2 billion on the Agulhas Plain alone; that the net present cost of invasion by black wattles amounts to US $ 1.4 billion; that invasions by red water fern have cost US $ 58 million; and that the cost to clear the alien plant invasions in South Africa is around US $ 1.2 billion. These few examples indicate that the economic consequences of invasions are huge. One of the unique aspects of invasive plant control programmes in South Africa has been the ability
Introduction pathways and establishment rates of invasive aquatic species in Europe. Canadian Journal of Fisheries and Aquatic Sciences 62
- In ‘Biological Invaders in Inland Waters: Profiles, Distribution and
, 2005
"... ..."
(Show Context)
2004a) Risk assessment for invasive species
- Risk Analysis
"... Although estimates vary, there is a broad agreement that invasive species impose major costs on the U.S. economy, as well as posing risks to nonmarket environmental goods and services and to public health. The domestic effort to manage risks associated with invasive species is coordinated by the Nat ..."
Abstract
-
Cited by 16 (0 self)
- Add to MetaCart
(Show Context)
Although estimates vary, there is a broad agreement that invasive species impose major costs on the U.S. economy, as well as posing risks to nonmarket environmental goods and services and to public health. The domestic effort to manage risks associated with invasive species is coordinated by the National Invasive Species Council (NISC), which is charged with devel-oping a science-based process to evaluate risks associated with the introduction and spread of invasive species. Various international agreements have also elevated invasive species issues onto the international policy agenda. The World Trade Organization (WTO) Sanitary and Phytosanitary (SPS) Agreement establishes rights and obligations to adhere to the discipline of scientific risk assessment to ensure that SPS measures are applied only to the extent required to protect human, animal, and plant health, and do not constitute arbitrary or unjustifiable technical barriers to trade. Currently, however, the field of risk assessment for invasive species is in its infancy. Therefore, there is a pressing need to formulate scientifically sound methods and approaches in this emerging field, while acknowledging that the demand for situation-specific empirical evidence is likely to persistently outstrip supply. To begin addressing this need, the Society for Risk Analysis Ecological Risk Assessment Specialty Group and the Eco-
REPORT The Allee effect, stochastic dynamics and the eradication of alien species
"... Previous treatments of the population biology of eradication have assumed that eradication can only be achieved via 100 % removal of the alien population. However, this assumption appears to be incorrect because stochastic dynamics and the Allee effect typically contribute to the extinction of very ..."
Abstract
-
Cited by 16 (4 self)
- Add to MetaCart
Previous treatments of the population biology of eradication have assumed that eradication can only be achieved via 100 % removal of the alien population. However, this assumption appears to be incorrect because stochastic dynamics and the Allee effect typically contribute to the extinction of very low-density populations. We explore a model that incorporates Allee dynamics and stochasticity to observe how these two processes contribute to the extinction of isolated populations following eradication treatments of varying strength (percentage mortality). As a case study, we used historical data on the dynamics of isolated gypsy moth, Lymantria dispar, populations to fit parameters to this model. The parameterized model was then used in simulations that evaluated the efficacy of various eradication strategies. The results indicated that eradication of isolated gypsy moth populations could be easily achieved following a treatment of>80 % mortality as long as populations were relatively low (indicated by <100 males captured in pheromone traps).
Invasive plants can inhibit native tree seedlings: testing potential allelopathic mechanisms
- Plant Ecology
, 2005
"... The mechanisms by which invasive species affect native communities are not well resolved. For example, invasive plants may influence other species through competition, altered ecosystem processes, or other pathways. We investigated one potential mechanism by which invasive plants may harm native spe ..."
Abstract
-
Cited by 13 (3 self)
- Add to MetaCart
(Show Context)
The mechanisms by which invasive species affect native communities are not well resolved. For example, invasive plants may influence other species through competition, altered ecosystem processes, or other pathways. We investigated one potential mechanism by which invasive plants may harm native species, allelopathy. Specifically, we explored whether native tree species respond differently to potential allelo-pathic effects of two invasive plant species. We assessed the separate effects of Lolium arundinaceam (tall fescue) and Elaeagnus umbellata (autumn olive) on three common successional tree species: Acer sac-charinum (silver maple), Populus deltoides (eastern cottonwood), and Platanus occidentalis (sycamore). Tall fescue and autumn olive are widely planted and highly invasive or persistent throughout North America where they often grow in forest edges, old fields, and other sites colonized by pioneering tree species. In an exploratory greenhouse experiment, we applied aqueous extracts derived from soil, leaf litter, or live leaves to native trees. We compared these treatments to a sterile water control and also to minced leaves leached in water, a common, but potentially less realistic method of testing for allelopathy. For all tree species, minced leaves from tall fescue reduced the probability that seedlings emerged, and minced leaves of autumn olive reduced the number of days to emergence. During other demographic stages, the three native tree species
Ecological and socioeconomic impacts of invasive alien species in
"... island ecosystems ..."
(Show Context)
The effects of introduced water hyacinth on habitat structure, invertebrate assemblages, and fish diets
- Estuaries
, 2003
"... ABSTRACT: The South American floating aquatic plant water hyacinth (Eichhornia crassipes) has a history of worldwide invasions, including a 1904 introduction into the Sacramento-San Joaquin Delta, California. The native pennywort (Hydrocotyle umbellata) occupies similar habitats in the Delta and is ..."
Abstract
-
Cited by 8 (0 self)
- Add to MetaCart
ABSTRACT: The South American floating aquatic plant water hyacinth (Eichhornia crassipes) has a history of worldwide invasions, including a 1904 introduction into the Sacramento-San Joaquin Delta, California. The native pennywort (Hydrocotyle umbellata) occupies similar habitats in the Delta and is extensively used by resident invertebrates and fish. We sought to discover if an invader would be functionally equivalent to the native plant, by asking whether the encroaching hyacinth modified the invertebrate assemblage structure and fish-invertebrate food web relative to pennywort. We sampled epiphytic, epibenthic, and benthic invertebrates, and plant canopy insects in patches of hyacinth and pennywort, and analyzed fish diets at three sites in the Delta during 1998. We also measured habitat structure (leaf density, root biomass, and surface area). In 1999, following control and absence of hyacinth, we again measured epiphytic invertebrates in pennywort. We found differences between hyacinth and pennywort in structure, associated invertebrates, and fish diets. Most measurements inferred functional non-equivalency between hyacinth and pennywort, although some functional equivalency and natural variation existed. Leaf and insect densities were significantly higher in pennywort and there were also significant differences in insect assemblage compositions. Hyacinth roots in the water column had significantly more surface area. Densities of epibenthic and benthic aquatic invertebrates were typically greater in pennywort and taxonomic compositions of aquatic invertebrate assemblages showed significant differences. Amphipods and isopods living epiphytically in the root masses were particularly abundant, including several newly discovered introduced species: the amphipod Crangonyx floridanus and the isopods Caecidotea racovitzai and Asellus hilgendorfii. The native amphipod Hyalella azteca was more abundant in pennywort and heavily preyed upon by fish, while the non-indigenous C. floridanus was more abundant in hyacinth and not prevalent in fish diets. The introduction of hyacinth to the Delta has caused significant ecological alterations in the surrounding community, due to hyacinth being functionally different from native patches of pennywort.
