ZAVALETA, HOBBS & MOONEY 2001

Viewing invasive species removal in a whole-ecosystem context


Eradications of invasive species often have striking positive effects on native biota. However, recent research has shown that species removal in isolationcan also result in unexpected changes to other ecosystem components. These secondary effects will become more likely as numbers of interacting invaders increase in ecosystems, and as exotics in late stages of invasion eliminate native species and replace their functional roles. Food web and functional role frameworks can be used to identify ecological conditions that forecast the potential for unwanted secondary impacts. Integration of eradication into a holistic process of assessment and restoration will help safeguard against accidental, adverse effects on native ecosystems.


Link: http://planet.uwc.ac.za/nisl/Invasives/Assignment1/Zavaleta.pdf

Difficulty C


Dr Richard Knight Co-ordinator: National Information Society Learnerships - Ecological Informatics
Department of Biodiversity and Conservation Biology
University of the Western Cape
Private Bag X17
Bellville 7535

Phone 27 + 21 + 959 3940
Fax 27 + 21 + 959 1237

Email Rknight@uwc.ac.za
Web http://nisl.uwc.ac.za

WILES ET AL. 2003

Impacts of the Brown Tree Snake: Patterns of Decline and Species Persistence in Guam’s Avifauna


Predation by brown tree snakes (Boiga irregularis) devastated the avifauna of Guam in the Mariana Islands during the last half of the twentieth century, causing the extirpation or serious reduction of most of the island’s 25 resident bird species. Past studies have provided qualitative descriptions of the decline of native forest birds but have not considered all species or presented quantitative analyses. We analyzed two sets of survey data gathered in northern Guam between 1976 and 1998 and reviewed unpublished sources to provide a comprehensive account of the impact of brown tree snakes on the island’s birds. Our results indicate that 22 species, including 17 of 18 native species, were severely affected by snakes. Twelve species were likely extirpated as breeding residents on the main island, 8 others experienced declines of >90% throughout the island or at least in the north, and 2 were kept at reduced population levels during all or much of the study. Declines of >90% occurred rapidly, averaging just 8.9 years along three roadside survey routes combined and 1.6 years at a 100-ha forested study site. Declines in northern Guam were also relatively synchronous and occurred from about 1976 to 1986 for most species. The most important factor pre-disposing a species to coexistence with brown tree snakes was its ability to nest and roost at locations where snakes were uncommon. Large clutch size and large body size were also related to longer persistence times, although large body size appeared to delay, but not prevent, extirpation. Our results draw attention to the enormous detrimental impact that brown tree snakes are likely to have upon invading new areas. Increased containment efforts on Guam are needed to prevent further colonizations, but a variety of additional management efforts would also benefit the island’s remaining bird populations.


Link: http://planet.uwc.ac.za/nisl/Invasives/Assignment1/Wiles.pdf


Difficulty B

Dr Richard Knight Co-ordinator: National Information Society Learnerships - Ecological Informatics
Department of Biodiversity and Conservation Biology
University of the Western Cape
Private Bag X17
Bellville 7535

Phone 27 + 21 + 959 3940
Fax 27 + 21 + 959 1237

Email Rknight@uwc.ac.za
Web http://nisl.uwc.ac.za

WELTZIN, BELOTE & SANDERS 2003

Biological invaders in a greenhouse world: will elevated CO2 fuel plant invasions?


Climate change and biological invasions, two of the hottest topics in ecology, both have ecological and societal implications, but they have developed on separate and parallel paths. Both are likely to have global impacts, yet researchers seldom explicitly consider their interaction. We argue that changes in atmospheric concentrations of carbon dioxide (CO2) and subsequent climate change may facilitate biological invasions, both directly and indirectly, and that our research agenda to date has left us poorly prepared to predict the consequences for communities and ecosystems. Forecasting the impact of biological invaders or elevated CO2 is a challenge for ecologists, and it is therefore prudent and timely to investigate the greater challenge, namely predicting the combined effects of invaders and elevated CO2 on native ecological systems.


Link: http://planet.uwc.ac.za/nisl/Invasives/Assignment1/Weltzin.pdf


Difficulty C


Dr Richard Knight Co-ordinator: National Information Society Learnerships - Ecological Informatics
Department of Biodiversity and Conservation Biology
University of the Western Cape
Private Bag X17
Bellville 7535

Phone 27 + 21 + 959 3940
Fax 27 + 21 + 959 1237

Email Rknight@uwc.ac.za
Web http://nisl.uwc.ac.za

VERMEIJ 1996

An Agenda for Invasion Biology


Here I advocate a comparative and systematic approach in which invasion (the extension of species ranges to areas not previously occupied by that species) is studied from the perspective of individual species as well as of the regions and biotas that export and receive invaders. In order to go beyond the particulars of invasion, it is important to ask: (1) how invaders differ from non-invaders in the arrival, establishment, and integration phases of invasion; (2) how donor regions or communities that have produced many successful invaders differ from those in which few resident species have been able to extend their ranges; (3) how recipient ecosystems with many successfully established invaders differ from those in which few species have taken hold, and (4) how invasion affects evolution not only of the invader itself, but of species in the recipient community with which the invader interacts.


Link: http://planet.uwc.ac.za/nisl/Invasives/Assignment1/Vermeij.pdf


Difficulty B

Dr Richard Knight Co-ordinator: National Information Society Learnerships - Ecological Informatics
Department of Biodiversity and Conservation Biology
University of the Western Cape
Private Bag X17
Bellville 7535

Phone 27 + 21 + 959 3940
Fax 27 + 21 + 959 1237

Email Rknight@uwc.ac.za
Web http://nisl.uwc.ac.za

SHAPIRO 2002

The Californian urban butterfly fauna is dependent on alien plants

Using the unusually well-documented butterfly fauna of Davis, Yolo County, California, it is shown that the mainly native species commonly observed in gardens breed mostly or entirely on alien plants, especially naturalized weeds. Over 40% of the fauna has no known native hosts in the urban–suburban environment. Were certain alien weeds to be eradicated or their abundance greatly reduced, the urban-suburban butterfly fauna would disappear. This might be regarded as an unfortunate, and perhaps intolerable, side-effect of such programs.


Link: http://planet.uwc.ac.za/nisl/Invasives/Assignment1/Shapiro.pdf


Difficulty B


Dr Richard Knight Co-ordinator: National Information Society Learnerships - Ecological Informatics
Department of Biodiversity and Conservation Biology
University of the Western Cape
Private Bag X17
Bellville 7535

Phone 27 + 21 + 959 3940
Fax 27 + 21 + 959 1237

Email Rknight@uwc.ac.za
Web http://nisl.uwc.ac.za

RICHARDSON & VAN WILGEN 2004

Invasive alien plants in South Africa: how well do we understand the ecological impacts?


This paper examines the evidence for the effects of invasive alien plants in natural and semi-natural ecosystems in South Africa. Invasive alien plants are concentrated in the Western Cape, along the eastern seaboard, and into the eastern interior, but there is a shortage of accurate data on abundance within this range. Most information on site-specific impacts comes from the fynbos biome, and is generally poor for other biomes. The consequences of invasions for the delivery of ecosystem goods and services to people are, with the notable exception of their influence on water resources, inadequately studied. Our understanding of many of the broader aspects of invasion ecology needs to be enhanced, and we identify important challenges for research to address critical gaps in knowledge. Priorities for future research include the development of a predictive understanding of the rates of spread of invasive alien plants, and the development of achievable goals for ecosystem repair after clearing, including measurable criteria for assessing the success of restoration. Climate change could significantly exacerbate problems with invasive species and work is needed to accommodate plausible trajectories in planning and management frameworks. Perhaps the greatest challenge for South African ecologists is to address the twin issues of skills development and social transformation, to ensure that adequate and relevant ecological expertise is maintained to meet future research and management needs. Formal collaboration between organizations to address capacity building and educational transformation in the field of invasion ecology would represent a significant step forward.


Link: http://planet.uwc.ac.za/nisl/Invasives/Assignment1/RichardsonandvanWilgen.pdf


Difficulty B


Dr Richard Knight Co-ordinator: National Information Society Learnerships - Ecological Informatics
Department of Biodiversity and Conservation Biology
University of the Western Cape
Private Bag X17
Bellville 7535

Phone 27 + 21 + 959 3940
Fax 27 + 21 + 959 1237


Email Rknight@uwc.ac.za
Web http://nisl.uwc.ac.za

RICHARDSON ET AL. 2000

Plant invasions ± the role of mutualisms

Many introduced plant species rely on mutualisms in their new habitats to overcome barriers to establishment and to become naturalized and, in some cases, invasive. Mutualisms involving animal mediated pollination and seed dispersal, and symbioses between plant roots and microbiota often facilitate invasions. The spread of many alien plants, particularly woody ones, depends on pollinator mutualisms. Most alien plants are well served by generalist pollinators (insects and birds), and pollinator limitation does not appear to be a major barrier for the spread of introduced plants (special conditions relating to Ficus andorchids are described). Seeds of many of the most notorious plant invaders are dispersed by animals, mainly birds and mammals. Our review supports the view that tightly coevolved, plant-vertebrate seed dispersal systems are extremely rare. Vertebrate-dispersed plants are generally not limited reproductively by the lack of dispersers. Most mycorrhizal plants form associations with arbuscular mycorrhizal fungi which, becauseof their low specificity, do not seem to play a major role in facilitating or hindering plant invasions (except possibly on remote islands such as the Galapagos which are poor in arbuscular mycorrhizal fungi). The lack of symbionts has, however, been a major barrier for many ectomycorrhizal plants, notably for Pinus spp. inparts of the southern hemisphere. The roles of nitrogen-fixing associations between legumes and rhizobia and between actinorhizal plants and Frankia spp. in promoting or hindering invasions have been virtually ignoredin the invasions literature. Symbionts required to induce nitrogen fixation in many plants are extremely widespread, but intentional introductions of symbionts have altered the invasibility of many, if not most, systems. Some of the world's worst invasive alien species only invaded after the introduction of symbionts. Mutualisms in the new environment sometimes re-unite the same species that form partnerships in the native range of the plant. Very often, however, different species are involved, emphasizing the diffuse nature ofmany (most) mutualisms. Mutualisms in new habitats usually duplicate functions or strategies that exist in the natural range of the plant. Occasionally, mutualisms forge totally novel combinations, with profound implications for the behaviour of the introduced plant in the new environment (examples are seed dispersal mutualisms involving wind-dispersed pines and cockatoos in Australia; and mycorrhizal associations involving plant roots and fungi). Many ecosystems are becoming more susceptible to invasion by introduced plants because: (a) they contain an increasing array of potential mutualistic partners (e.g. generalist frugivores and pollinators, mycorrhizal fungi with wide host ranges, rhizobia strains with infectivity across genera); and (b) conditions conducive for the establishment of various alien/alien synergisms are becoming more abundant. Incorporating perspectives on mutualisms in screening protocols will improve (but not perfect) our ability to predict whether a given plant species could invade a particular habitat. Key words: biological invasions, global change, invasibility, mycorrhiza, nitrogen fixation, pollination, prediction, risk assessment, seed dispersal.


Link: http://planet.uwc.ac.za/nisl/Invasives/Assignment1/Richardson.pdf

Difficulty A

Dr Richard Knight Co-ordinator: National Information Society Learnerships - Ecological Informatics
Department of Biodiversity and Conservation Biology
University of the Western Cape Private
Bag X17
Bellville 7535

Phone 27 + 21 + 959 3940
Fax 27 + 21 + 959 1237

Email Rknight@uwc.ac.za
Web http://nisl.uwc.ac.za

PETIT 2004

Biological invasions at the gene level


Despite several recent contributions of population and evolutionary biology to the rapidly developing field of invasion biology, integration is far from perfect. I argue here that invasion and native status are sometimes best discussed at the level of the gene rather than at the level of the species. This, and the need to consider both natural (e.g. postglacial) and human-induced invasions, suggests that a more integrative view of invasion biology is required.


Link: http://planet.uwc.ac.za/nisl/Invasives/Assignment1/Petit.pdf

Difficulty C

Dr Richard Knight Co-ordinator: National Information Society Learnerships - Ecological Informatics
Department of Biodiversity and Conservation Biology
University of the Western Cape
Private Bag X17
Bellville 7535

Phone 27 + 21 + 959 3940
Fax 27 + 21 + 959 1237

Email Rknight@uwc.ac.za
Web http://nisl.uwc.ac.za

PETERSON & VIEGLAIS 2001

Predicting Species Invasions Using Ecological Niche Modeling: New Approaches from Bioinformatics Attack a Pressing Problem


On 3 February 1999, President Clinton signed an executive order dealing with invasive species in the United States. The order was designed to lay the foundation for a program “to prevent the introduction of invasive species and provide for their control and to minimize the economic, ecological, and human health impacts that invasive species cause” (Clinton 1999). This program includes far-reaching plans to prevent, plan, monitor, and study species’ invasions. Such high-level attention emphasizes the enormity of the problem facing the United States, and in fact the entire world: With ever-growing international commerce, reduced barriers to trade, and increasing human influence, species are moving around, and natural systems are suffering drastic changes. The dimensions of the problem are indeed impressive. Alien plants, animals, and microbes have poured into theUnited States from all directions. Natural systems have been disrupted, species extinguished, transportation and agriculture compromised, and resources damaged (Carlton1997–1998, Ogutu-Ohwayo 1997–1998, Richardson1997–1998, Shiva 1997–1998). In fact, most modern agricultureis based on non-native organisms; problems arise because questions of when and why some escape and become nuisances remain unanswered. More generally, no proactive approach to combating such species is available—invasive species are dealt with one at a time, as they become problematic.


Link: http://planet.uwc.ac.za/nisl/Invasives/Assignment1/PetersonandVieglais.pdf

Difficulty B

Dr Richard Knight Co-ordinator: National Information Society Learnerships - Ecological Informatics
Department of Biodiversity and Conservation Biology
University of the Western Cape
Private Bag X17
Bellville 7535

Phone 27 + 21 + 959 3940
Fax 27 + 21 + 959 1237

Email Rknight@uwc.ac.za
Web http://nisl.uwc.ac.za

O'DOWD, GREENT & LAKE 2003

Invasional "meltdown" on an oceanic island


Islands can serve as model systems for understanding how biological invasions affect community structure and ecosystem function. Here we show invasion by the alien crazy ant Anoplolepis gracilipes causes a rapid, catastrophic shift in the rain forest ecosystem of atropical oceanic island, affecting at least three trophic levels. In invaded areas, crazy ants extirpate the red land crab, the dominant endemic consumer on the forest floor. In doing so, crazy ants indirectly release seedling recruitment, enhance species richness of seedlings, and slow litter breakdown. In the forest canopy, new associations between this invasive ant and honeydew-secreting scale insects accelerate and diversify impacts. Sustained high densities of foraging ants on canopy trees result in high population densities of host generalist scale insects and growth of sooty moulds, leading to canopy dieback and even deaths of canopy trees. The indirect fallout from the displacement of a native "keystone" species by an ant invader, itself abetted by introduced/cryptogenic mutualists, produces synergism in impacts to precipitate invasional "meltdown" in this system.


Link: http://planet.uwc.ac.za/nisl/Invasives/Assignment1/ODowd.pdf


Difficulty C

Dr Richard Knight Co-ordinator: National Information Society Learnerships - Ecological Informatics
Department of Biodiversity and Conservation Biology
University of the Western Cape
Private Bag X17
Bellville 7535

Phone 27 + 21 + 959 3940
Fax 27 + 21 + 959 1237

Email Rknight@uwc.ac.za
Web http://nisl.uwc.ac.za

MEYERS ET AL. 2000

Eradication revisited: dealing with exotic species


Invasions of non-indigenous species threaten native biodiversity, ecosystem functioning, animal and plant health, and human economies. The best solution is to prevent the introduction of exotic organisms but, once introduced, eradication might be feasible. The potential ecological and social ramifications of eradication projects make them controversial; however, these programs provide unique opportunities for experimental ecological studies. Deciding whether to attempt eradication is not simple and alternative approaches might be preferable in some situations.


Link: http://planet.uwc.ac.za/nisl/Invasives/Assignment1/Myers.pdf


Difficulty C


Dr Richard Knight Co-ordinator: National Information Society Learnerships - Ecological Informatics
Department of Biodiversity and Conservation Biology
University of the Western Cape
Private Bag X17
Bellville 7535

Phone 27 + 21 + 959 3940
Fax 27 + 21 + 959 1237

Email Rknight@uwc.ac.za
Web http://nisl.uwc.ac.za

LeMAITRE 2004

Alien plant invasions in South Africa: driving forces and the human dimension


Invasive alien plants pose a substantial threat to the rich biodiversityof South Africa, and to the sustained delivery of a wide range of ecosystem services. Biological invasions are driven by human activities and mediated by culturally shaped values andethics. This paper explores the human dimensions of alien plant invasions in South Africa. We consider four primary forces, those which directly influence the likelihood and rate of invasion—arrival of propagules; changes in disturbance regimes; changes in the availability of limiting factors; and fragmentation of the landscape— and the roles of 22 secondary driving forces in shapingthe outcomes of the four primary driving forces. Human societies and their dynamics and activities are an integral part of each of the secondary driving forces. A map of the interactions between and among the primary and secondary driving forces shows how they are interlinked and influence each other—either positively or negatively, or switching between the two. There are two key points for intervention: prevention of the introduction of propagules of potentially invasive species and developing collaborative initiatives with enterprises that rely largely on alien species (for example, horticulture, agriculture and forestry, including community forestry) to minimize the introduction and use of potentially invasive species. An example of the first type of intervention would be to implement more effective inspection systems at international border and customs posts. This type of intervention can only be effective if those who are directly affected—whether businessmen, tourists or migrants — understand the requirement for these measures, and collaborate. The need to build public awareness of the critical importance of the human dimension of invasions emerges as a key theme from this analysis and is the basis for better-informed decisions, more effective control programmes and a reduction of further invasions.


Link:
http://planet.uwc.ac.za/nisl/Invasives/Assignment1/LeMaitre.pdf


Difficulty B


Dr Richard Knight Co-ordinator: National Information Society Learnerships - Ecological Informatics
Department of Biodiversity and Conservation Biology
University of the Western Cape
Private Bag X17
Bellville 7535

Phone 27 + 21 + 959 3940
Fax 27 + 21 + 959 1237

Email Rknight@uwc.ac.za
Web http://nisl.uwc.ac.za

KEANE & CRAWLEY 2002

Exotic plant invasions and the enemy release hypothesis


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 under-studied 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.


Link:
http://planet.uwc.ac.za/nisl/Invasives/Assignment1/KeaneandCrawley.pdf


Difficulty B

Dr Richard Knight Co-ordinator: National Information Society Learnerships - Ecological Informatics
Department of Biodiversity and Conservation Biology
University of the Western Cape
Private Bag X17
Bellville 7535

Phone 27 + 21 + 959 3940
Fax 27 + 21 + 959 1237

Email Rknight@uwc.ac.za
Web http://nisl.uwc.ac.za

GIRAUD 2002

Evolution of supercolonies: The Argentine ants of southern Europe

Some ants have an extraordinary social organization, called unicoloniality, whereby individuals mix freely among physically separated nests. This type of social organization is not only a key attribute responsible for the ecological domination of these ants, but also an evolutionary paradox and a potential problem for kin selection theory because relatedness between nest mates is effectively zero. The introduction of the Argentine ant in Europe was apparently accompanied by a dramatic loss of inter-nest aggression and the formation of two immense supercolonies (which effectively are two unicolonial populations). Introduced pulations experienced only limited loss of genetic diversity at neutral markers, indicating that the breakdown of recognition ability is unlikely to be merely due to a genetic bottleneck. Rather, we suggest that a ‘‘genetic cleansing’’ of recognition cues occurred after introduction. Indeed workers of the same supercolony are never aggressive to each other despite the large geographical distance and considerable genetic differentiation between sampling sites. By contrast, aggression is invariably extremely high between the two supercolonies, indicating that they have become fixed for different recognition alleles. The main supercolony, which ranges over 6,000 km from Italy to the Spanish Atlantic coast, effectively forms the largest cooperative unit ever recorded.


Link:
http://planet.uwc.ac.za/nisl/Invasives/Assignment1/Giraud.pdf

Difficulty C

Dr Richard Knight Co-ordinator: National Information Society Learnerships - Ecological Informatics
Department of Biodiversity and Conservation Biology
University of the Western Cape
Private Bag X17
Bellville 7535

Phone 27 + 21 + 959 3940
Fax 27 + 21 + 959 1237

Email Rknight@uwc.ac.za
Web http://nisl.uwc.ac.za

DUKES & MOONEY 1999

Does global change increase the success of biological invaders?


Biological invasions are gaining attention as a major threat to biodiversity and an important element of global change. Recent research indicates that other components of global change, such as increases in nitrogen deposition and atmospheric CO2 concentration, favor groups of species that share certain physiological or life history traits. New evidence suggests that many invasive species share traits that will allow them to capitalize on the various elements of global change. Increases in the prevalence of some of these biological invaders would alter basic ecosystem properties in ways that feed back to affect many components of global change.


Link: http://planet.uwc.ac.za/nisl/Invasives/Assignment1/DukesandMooney.pdf


Difficulty C


Dr Richard Knight Co-ordinator: National Information Society Learnerships - Ecological Informatics
Department of Biodiversity and Conservation Biology
University of the Western Cape
Private Bag X17
Bellville 7535

Phone 27 + 21 + 959 3940
Fax 27 + 21 + 959 1237

Email Rknight@uwc.ac.za
Web http://nisl.uwc.ac.za

BINNS, ILLGNER & NEL 2001

Water Shortage, Deforestation and Development: South Africa's Working for Water Programme


In the post-apartheid era, South Africa is experiencing a serious water supply crisis as demand increases from both rural areas and rapidly growing towns and cities. New dams and water transfer schemes are being constructed, but they are both controversial and unlikely to fully satisfy demand. Alien species of trees and plants have invaded many plants of the country, taking over land from indigenous species. These alien species consume much more water than indigenous vegetation, as well as threatening biodiversity and constituting a significant fire hazzard. The Working for Water Programme, established in 1995, and working in partnership with local communities, aims to clear invasive alien species and thus increase water supply. The programme is examined in terms of its impacts on environment and the livelihoods of predominantly poor rural communities. Questions are raised about the future sustainability of the programme.

Link: http://planet.uwc.ac.za/nisl/invasives/Assignment1/Binns.pdf


Difficulty B


Dr Richard Knight Co-ordinator: National Information Society Learnerships - Ecological Informatics
Department of Biodiversity and Conservation Biology
University of the Western Cape
Private Bag X17
Bellville 7535

Phone 27 + 21 + 959 3940
Fax 27 + 21 + 959 1237

Email Rknight@uwc.ac.za

Web http://nisl.uwc.ac.za/

D'ANTONIO & MEYERSON 2002

Exotic Plant Species as Problems and Solutions in Ecological Restoration: A Synthesis

Exotic species have become increasingly significant management problems in parks and reserves and frequently complicate restoration projects. At the same time there may be circumstances in which their removal may have unforeseen negative consequences or their use in restoration is desirable. We review the types of effects exotic species may have that are important during restoration and suggest research that could increase our ability to set realistic management goals. Their control and use may be controversial; therefore we advocate consideration of exotic species in the greater context of community structure and successionand emphasize areas where ecological research could bring insight to management dilemmas surrounding exotic species and restoration. For example, an understanding of the potential transience ofexotics in a site and the role particular exotics might play in changing processes that influence the course of succession is essential to setting removal priorities and realistic management goals. Likewise, a greater understanding of the ecological role of introduced species might help to reduce controversy surrounding their purposeful use in restoration. Here we link generalizations emerging from the invasion ecology literature with practical restoration concerns, including circumstances when it is practical to use exotic species in restoration.


Link: http://planet.uwc.ac.za/nisl/Invasives/Assignment1/DAntonioandMeyerson.pdf


Difficulty B


Dr Richard Knight Co-ordinator: National Information Society Learnerships - Ecological Informatics
Department of Biodiversity and Conservation Biology
University of the Western Cape
Private Bag X17
Bellville 7535

Phone 27 + 21 + 959 3940
Fax 27 + 21 + 959 1237

Email Rknight@uwc.ac.za
Web http://nisl.uwc.ac.za/

COLAUTTI & MacISAAC 2004

A neutral terminology to define ‘invasive’ species

The use of simple terms to articulate ecological concepts can confuse ideological debates and undermine management efforts. This problem is particularly acute in studies of non-indigenous species, which alternatively have been called ‘exotic’, ‘introduced’, ‘invasive’ and ‘naturalised’, among others. Attempts to redefine commonly used terminology have proven difficult because authors are often partial to particular definitions. In an attempt to form a consensus on invasion terminology,we synthesize an invasional framework based on current models that break the invasion process into a series of consecutive, obligatory stages. Unlike previous efforts, we propose a neutral terminology based on this framework. This ‘stagebased’ terminology can be used to supplement terms with ambiguous meanings (e.g. invasive, introduced, naturalized, weedy, etc.), and thereby improve clarity of future studies. This approach is based on the concept of ‘propagule pressure’ and has the additional benefit of identifying factors affecting the success of species at each stage. Under this framework, invasions can be more objectively understood as biogeographical, rather than taxonomic, phenomena; and author preferences in the use of existing terminology can be addressed. An example of this recommended protocol might be: ‘We examined distribution data to contrast the characteristics of invasive species (stages IVa and V) and non-invasive species (stages III and IVb)’.

Link: http://planet.uwc.ac.za/nisl/Invasives/Assignment1/ColauttiandMacIsaac.pdf

Difficulty C

Dr Richard Knight Co-ordinator: National Information Society Learnerships - Ecological Informatics
Department of Biodiversity and Conservation Biology
University of the Western Cape
Private Bag X17
Bellville 7535

Phone 27 + 21 + 959 3940
Fax 27 + 21 + 959 1237

Email Rknight@uwc.ac.za
Web http://nisl.uwc.ac.za/

BERTOLINO & GEN0VESI 2002

Spread and attempted eradication of the grey squirrel (Sciurus carolinensis) in Italy, and consequences for the red squirrel (Sciurus vulgaris) in Eurasia.


In 1997, the National Wildlife Institute, in co-operation with the University of Turin, produced an action plan to eradicate theAmerican grey squirrel from Italy, as this introduced species replaces the native red squirrel through competitive exclusion anddamages trees through de-barking. The first step, a trial eradication of a small population of grey squirrels at Racconigi (Turin) toevaluate the efficiency of the removal techniques, started in May 1997. Preliminary results showed that eradication was feasible, butthe project was opposed by radical animal rights groups which took the National Wildlife Institute to court in June 1997. This legalaction caused a suspension of the project and led to a lengthy judicial enquiry that ended in July 2000 with the acquittal of theInstitute. Nevertheless, the 3-year suspension of all actions led to a significant expansion of the grey squirrel’s range and thus eradicationis no longer considered practical. Therefore, in the medium to long term, grey squirrels are likely to expand through continentalEurasia. This constitutes a major threat to the survival of the red squirrel over a large portion of its distribution range andwill have a significant impact on forests, with economic damage to timber crops.


Link: http://planet.uwc.ac.za/nisl/Invasives/Assignment1/BertolinoandGenovesi.pdf


Difficulty B


Dr Richard Knight Co-ordinator: National Information Society Learnerships - Ecological Informatics
Department of Biodiversity and Conservation Biology University of the Western Cape
Private Bag X17
Bellville 7535

Phone 27 + 21 + 959 3940
Fax 27 + 21 + 959 1237

Email Rknight@uwc.ac.za
Web http://nisl.uwc.ac.za

BENNING 2002

Interactions of climate change with biological invasions and land use in the Hawaiian Islands: Modeling the fate of endemic birds using a geographic information system


The Hawaiian honeycreepers (Drepanidae) represent a superbillustration of evolutionary radiation, with a single colonizationevent giving rise to 19 extant and at least 10 extinct species[Curnutt, J. & Pimm, S. (2001) Stud. Avian Biol. 22, 15–30]. They alsorepresent a dramatic example of anthropogenic extinction. Cropand pasture land has replaced their forest habitat, and humanintroductions of predators and diseases, particularly of mosquitoesand avian malaria, has eliminated them from the remaining lowandmid-elevation forests. Landscape analyses of three highelevationforest refuges show that anthropogenic climate changeis likely to combine with past land-use changes and biologicalinvasions to drive several of the remaining species to extinction,especially on the islands of Kauai and Hawaii.


Link: http://planet.uwc.ac.za/nisl/Invasives/Assignment1/Benning.pdf


Difficulty C

Dr Richard Knight Co-ordinator: National Information Society Learnerships - Ecological Informatics
Department of Biodiversity and Conservation Biology
University of the Western Cape
Private Bag X17
Bellville 7535

Phone 27 + 21 + 959 3940
Fax 27 + 21 + 959 1237

Email Rknight@uwc.ac.za
Web http://nisl.uwc.ac.za/

ALPERT, BONE & HOLZAPFEL 2000

Invasiveness, invasibility and the role of environmental stress in the spread of non-native plants

Invasion ecology, the study of how organisms spread in habitats to which they are not native, asks both about the invasiveness of species and the invasibility of habitats: Which species are most likely to become invasive? Which habitats are most susceptible to invasion? To set the stage for considering these questions with regard to plants, we offer a two-way classification of nativeness and invasiveness that distinguishes natives, non-invasive non-natives and invasive non-natives. We then consider the current state of knowledge about invasiveness and invasibility. Despite much investigation, it has proven difficult to identify traits that consistently predict invasiveness. This may be largely because different traits favour invasiveness in different habitats. It has proven easier to identify types of habitats that are relatively invasible, such as islands and riverbanks. Factors thought to render habitats invasible include low intensities of competition, altered disturbance regimes and low levels of environmental stress, especially high resource availability. These factors probably often interact; the combination of altered disturbance with high resource availability may particularly promote invasibility. When biotic factors control invasibility, non-natives that are unlike native species may prove more invasive; the converse may also be true. We end with a simple conceptual model for cases in which high levels of environmental stress should and should not reduce invasibility. In some cases, it may be possible to manipulate stress to control biological invasions by plants.


Link: http://planet.uwc.ac.za/nisl/Invasives/Assignment1/Alpert.pdf


Difficulty A

Dr Richard Knight Co-ordinator: National Information Society Learnerships - Ecological Informatics
Department of Biodiversity and Conservation Biology
University of the Western Cape
Private Bag X17
Bellville 7535

Phone 27 + 21 + 959 3940
Fax 27 + 21 + 959 1237

Email Rknight@uwc.ac.za
Web http://nisl.uwc.ac.za/

ALLDORF & LUNDQUIST 2003:

Introduction: Population Biology, Evolution, and Control of Invasive Species


Invasion by nonindigenous species has been recognized as second only to loss of habitat and landscape fragmentation as a threat to global biodiversity (Walker & Steffen 1997 ). The economic impact of these species is a major concern throughout the world. For example, an estimated 50,000 nonindigenous species established in the United States cause major environmental damage and economic losses that total over an estimated U.S.$125 billion per year (Pimentel et al. 2000). Management and control of nonindigenous species is perhaps the biggest challenge that conservation biologists will face in the next few decades.


Link: http://planet.uwc.ac.za/nisl/Invasives/Assignment1/AllendorfandLundquist.pdf

Difficulty B

Dr Richard Knight Co-ordinator: National Information Society Learnerships - Ecological Informatics
Department of Biodiversity and Conservation Biology
University of the Western Cape
Private Bag X17
Bellville 7535

Phone 27 + 21 + 959 3940
Fax 27 + 21 + 959 1237

Email Rknight@uwc.ac.za
Web http://nisl.uwc.ac.za

ASSIGNMENT 1 (20%): REVIEWING A SCIENTIFIC PAPER

Hi Everyone

I will put up the abstracts of some 20 research papers, which you will review, and from your review you will prepare a Narrated Presentation. These Paper Reviews will be put up for all people to comment on. Our UWC students have completed theirs (David all parts) and Karen (just needing to add her narration - the original microphone supplied was poor quality).

A Review is NOT...

• just a summary of the paper.
• examination ONLY of the material contained in the paper.
• only a re-statement of the points made by the authors.

A Review IS...

• a critical but fair analysis of the quality of the research paper.
• putting the research into perspective of other research that has been undertaken.
• an expression (at least in part) of your own opinions and suggestions, including where improvements could be made.

In essence your review should been seen as a constructive critique and at least some reflections of your own points of view.

I will put up abstracts and links for each paper as individual postings and you will book by adding a comment confirming acceptance of this paper for your review.

Instruction Points

Use the latest template (since the CSIR logo has changed) and this can be downloaded from the following URL (Right Mouse Click and Save Target as)

http://planet.uwc.ac.za/nisl/NISL_templates/NISL_Template_EI_2.ppt

For each slide you will need an audio file using either your Windows Sound Recorder which limits sopund clips to 60 seconds or to download the free software Audacity

http://audacity.sourceforge.net/ (Sorry I cannot help you on learning how to use this!)

I have provided a mini-video showing you how to use your Windows Sound Recorder to make audio files. Audio files need to be name slide1, slide2 etc and when completed please use WinZip to zip the files to make a single compressed file for emailing to me. (if you do not know how to make a Zip File please let me know by adding a comment to this posting)

http://planet.uwc.ac.za/nisl/NISL_templates/Audio/recorder.html

The Ruderic for marking this assignment can be found at the following URL (Right Mouse click and Save Target as)

http://planet.uwc.ac.za/nisl/Invasives/Assignment1/

Please note that if you take a more difficult and longer paper may get awarded bonus marks (additional 10 marks), wheras very easy or short paper you will only get marked out of 90. Difficult or longer papers are indicated with an A, whereas the easiest papers are indicated with a C. Most of the papers are graded with a B and therefore are marked out of 100.

Final Deadline is 15 June 2006 and the PowerPoint should be emailed to mailto:toknight.rich@gmail.com (with the heading "Invasives_assignment_1") and the Document name: Initial_Surname_invasives_2006_assignment_1.ppt and Initial_Surname_invasives_2006_assignment_1.zip as the attached file names (failure to correctly name your files will or provide the incorrect heading for your email message will incur a 10% penalty). If your font page of your Power Point does not carry full contact details you will also be subject to a further 10% penalty.

Or

upload via ftp to the following directory (please ask by email for login details)
http://planet.uwc.ac.za/nisl/invasives/Assignments_collect/2006

Cheers

Rich