Invasive alien species


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Invasive alien species

  2. 2. Outline Introduction Conditions that lead to invasion -> Species-based mechanisms -> Ecosystem-based mechanisms Pathway of Introduction Impacts Control and management
  3. 3. Introduction An Invasive species is an organism that is not indigenous/native to its environment. Invasive species can be a plant, animal or insect. Different words are used to describe species occurring in
  4. 4. Introduction contd..According to the Global Invasive Species Program (GISP): “Invasive alien species (IAS) are non-native organisms that cause, or have the potential to cause, harm to the environment, economies, or
  5. 5.  Invasion is considered as the second most important threat to biodiversity after All Species habitat destruction. Marine Species Invasive species are so much important inthe present scenario that, article 8(h) of theBiodiversity Convention asks for measures ‘‘toprevent the introduction, control or even
  6. 6. Conditions thatTwo lead to that when combined mechanisms, invasion establish invasiveness in a newly introduced species;1. Species-based mechanisms Invasive species appear to have specific traits that allow them to outcompete native species. Common invasive species traits include: -Fast growth, for e.g.Mile-a-minute weed (Mikania micarantha),i) a fast Mikania
  7. 7. - Rapid reproduction - High dispersal ability - Phenotypic plasticity (the ability to alter growth ii) Barbed form to suit current conditions) goatgrass -Tolerance of a wide range of environmental conditions ( Ecological competence), For e.g. Barbed goatgrass (Aegilops triuncialis) introduced to California on serpentine soils (low water-
  8. 8. - They are usually generalist. - Association with humans - Prior successful invasions - Ecological facilitation Lantana iii) like alleopathy mechanism. For e.g. Lantana (Lantana camara).2. Ecosystem-based mechanisms describe a situation in which the
  9. 9. - changes such as a forest fire. For e.g. Bromus tectorum, highly fire-adapted. It not only spreads rapidly after burning but also increases the frequency and intensity of fires, by providing large amounts of dry detritus. iv) Bromus v) Water hyacinth
  10. 10. - Habitat fragmentation and Edge effect, brings change in species composition with invasion of exotic species. vi) woodthrush nest parasitized by cowbird
  11. 11. Pathway of Introduction Non-native species have many vectors, including many biogenic ones, but most species considered "invasive" are associated with human activity. vii) zebra mussel - Ballast water taken up at sea and released in port is a major
  12. 12. - Plants or seeds imported for horticulture.- The pet trade moves animals across borders, where they can escape and become invasive.- Chinese mitten crab, introduced viii) Chinese mitten crab in foreign water for economic purpose.
  13. 13. Impacts1. Ecological Disturbed habitats are prone to invasions that can have adverse effects on local ecosystems, changing ecosystem functions. In the Waterberg region of South Africa, cattle grazing over the past six centuries has allowed invasive scrub and small trees to displace
  14. 14.  Invasive species can change the functions of ecosystems. For example, invasive plants can alter the fire regimen (cheatgrass, Bromus tectorum), nutrient cycling (smooth cordgrass Spartina alterniflora), and hydrology (Tamrix) in native ecosystems.2. Economica) Benefits
  15. 15.  Vegetative invasives such as water hyacinth can be turned into fuel by methane digesters.b) Cost Estimated damage and control cost of invasive species in the U.S. alone amount to more than $138 billion annually. If monetary values were assigned to the extinction of
  16. 16. 3. Agriculture Many introduced weeds in agriculture field compete with native crops. ix) Mikania on banana plants A decline in pollinator services and loss of fruit production has been caused by honey bees infected by the invasive varroa mite. mite x) Varroa Introduced rats (Rattus rattus and
  17. 17. 4. Forestry The unintentional introduction of forest pest species and plant pathogens can change forest ecology. For e.g. Mikania micarantha xi) Mikania covering trees (Lahare banmara).5. Health Introduced birds (e.g. pigeons), rodents and insects (e.g. mosquito,
  18. 18. 6. Biodiversity Biotic invasion is considered one of the five top drivers for global biodiversity loss and is increasing because of tourism and globalization. xii) Invasive plant in Rhino xiii) American alligator attacking habitat a Burmese python in florida. Invasive species may drive local
  19. 19. Control and management xiv) Harvesting vehicles xv) Root talon xvi) weed wrench1. Physical (Mechanical) control- It involves directly removing the species by hand or with appropriate machines. - such as harvesting vehicles (e.g.,
  20. 20. 2. Chemical control- Involves the use of herbicides, insecticides, and rodenticides that primarily affect the target species.
  21. 21. 3. Biological control- Intentional use of populations of natural enemies of the target invasive alien species. For e.g. Mikania is an excellent example where this new generation of classical biological control agents, namely fungal pathogens are used to control it.4. Integrated pest management (IPM) and Habitat management
  22. 22. - Habitat management involves measures such as prescribed burning, grazing and other activities.- Therefore, given the high complexity of the ecology of invasive species and habitats affected, control
  23. 23. Conclusion Invasive Alien Species (IAS) are the second greatest threat to biological diversity globally and the highest threat on many island ecosystems. The adverse environmental impacts such as alteration of habitat and species composition have been experienced due to some alien species. The control and management of
  24. 24. References Drake, J. A., Mooney, H. A., Di Castri, F., Groves, R.H., Kruger, F. J., Rejmanek, M. and Williamson, M. 1989. Biological invasion: A global perspective. Scope 37. Wiley, Chichester, London, England. Mooney, H.A. and Hobbs, R.J. 2000. Invasive species in a changing world. Island (press,Washington, D.C.) Tiwari, S., Adhikari, B., Siwakoti, M. and Subedi, K. 2005. An inventory