Invasive

Invasive Species Donna Marie Tan Sarah Jane Toledo

What are “Invasive Species”? • The term “invasive species” is often said to be ‘ambiguous’ (Codman, 2005). - “An introduced species that out-competes native species for space and resources. Scotch Broom is an invasive species that out-competes local vegetation and results in a monoculture, and hence a decrease in local diversity. “ -oceanlink.island.net/glossary.html

What are “Invasive Species”? “An invasive species is a species occurring, as a result of human activities, beyond its accepted normal distribution and which threatens valued environmental, agricultural or other social resources by the damage it causes.” -http://www.environment.gov.au/biodiversity/invasive/

What are “Invasive Species”? Stage

Characteristic

2

Propagates, residing in a “donor” region Traveling

3

Introduced

4 5

Localized and numerically rare Widespread but rare

6

Localized but dominant

7

Widespread and dominant

1

How do these species get to certain places? Species sometimes are • Imported by people • Accidentally wanders to a certain place

How do these species get to certain places? • Examples of invasive species Kudzu, a Japanese species invasive in the southeast United States, growing in Atlanta, Georgia

• Examples of invasive species

Brown Tree Snake

Pied Currawong

• Species-based mechanisms Species-based characteristics focus on competition. While all species compete to survive, invasive species appear to have specific traits or combinations of specific traits that allow them to outcompete native species

• Ecosystem-based mechanisms -

Some invading species are able to fill niches that are not utilized by native species, and they also can create niches that did not exist.

What Threats Do Invasive Species Impose on the Environment? Invasive species may negatively impact native species in a number of ways. These include competition and predation with the native species, interbreeding and introduction of pathogens and parasites that sicken or kill the native species.

What Threats Do Invasive Species Impose on the Environment? • • • • • • •

Threats to native species Agricultural Impacts Impact on Forestry Impact on Fisheries Impact on Water-systems Impact on Human Health Genetic ‘Pollution’ or Uncontrolled Hybridization’

What has to be Done • Prevention is the single best way to limit impacts of nonnative species • Eradication may be feasible early in an invasion or in a restricted area • Containment is an important tool to reduce the impact of existing invaders. Strategies for containment generally combine tools used in prevention and eradication

• Control methods can include any of the following: – Chemical – Mechanical – Biological

• Restoration of native communities is an important step to minimize the chances an area will be reinvaded. Many control techniques inherently create disturbance, which may increase the vulnerability of an area to subsequent invaders

References • • •

Article on ‘Invasive Species’ source: http://en.wikipedia.org/wiki/Invasive_species Ecological Society of America. Handout on Invasive Species (2004) • www.esa.org/education/edupdfs/invasion.pdf. Retrieved on July 3, 2008. • Pimentel, D.; R. Zuniga and D., Morrison (2005). "Update on the environmental and economic costs associated with alieninvasive species in the United States.". Ecological Economics 52: 273–288. • Colautti, Robert I.; MacIsaac, Hugh J. (2004), “A neutral terminology to define 'invasive' species”, Diversity and Distributions 10: 135–141, doi:10.1111/j.13669516.2004.00061.x, . Retrieved on 2008-08-01