1. Invasive species:
boon or bane
Submitted by:-Manisha
Class:- M.sc.(P) Botany
Roll no. 22

2.  Introduction
 Characteristics of invasive species
 Invasion Rule
 Process of Invasion
 Pathways of introduction
 Deliberate
 Accidental
 Impacts of invasive species
 Examples
 Controlling measures
 Conclusion
 References

3. Introduction
Native species:- occurring within their
natural range.
Non-native species:- Introduced from
somewhere else into new area.
Invasive species:-
 Also called Non-natives, Introduced sp. ,
Non-indigenous, Exotic sp. ,Alien sp. ,
Foreign sp.etc.
 Non-native organisms that cause, or have
the potential to cause, harm to the
environment, economies, or human health.

4.  Fitness homeostasis
 Wide geographic range
 Highly successful seed dispersal, germination and
colonization
 Alternative mode of reproduction
 Strong competitors
 Allelopathic properties
 Have few natural predators, competitors, parasites
& diseases.
 High cost of removal and control
 Difficult to control or eliminate once established

5. statistical rule says that
 1 in 10 of imported species become
introduced
 1 in 10 of those introduced become
established
 1 in 10 of those established becomes
a pest
 All these stages have probability of
≈10%
→10’s rule (Williamson & Filter, 1996)

6. .Transport Introduction
Establishment Spread
Impact
Ecological, Economic, Human Health

7. Deliberately introduced
(Intentional/Purposeful introduction
 it refers to the movement of organisms to a
new area for an express purpose i.e some
benefit is expected .
Accidentally introduced
(Unintentional introduction)
 species that are transported as a byproduct
of movement of other goods.

8. Intentional transport
 For Food
 Game species
 Bio-control
 Ornamental plants
 Environmental
enhancement
 Conservation &
Scientific persuites
 Many nurseries &
hobbyists

9.  As hitchhikers.
 In containers,
packing material,
baggage, travelers.
 Attached to fishing
gear, anchors, lines.
 Non-Food Animal
Pathways (aquarium
trade, pets, non-
food livestock,
aquaculture, labs)
 Attached to ship
hulls.
Underwater view of a highly
fouled ship hull showing
attached fouling organisms

10. Movement of species within
ship ballast
 Ocean going
vessels must
balance their
cargo load to
stabilize the
ship.
 Species carried
in ballast
include insects,
plants,
earthworms &
many more
organisms.

11. Some of them are:-
 Invasive species can alter entire
ecosystem.
 Displace native species.
 Reduce forest health & productivity.
 Compete with & replace rare and
endangered species .
 Hybridize with native plant species, altering
their genetic makeup & reduce gene pool.
 Reduce the amount of space, water,
sunlight and nutrients that would be
available to native species .

12. Examples
Water Hyacinth
Eichhornia crassipes
 Native of Asia
 Invaded African rivers
& lakes.
 Can double its biomass
every 2-3 days.
 Carpet the surface of
water bodies with mats.
 Mats harbour
mosquitoes & snails.
 Brought from South
America.
 Double its biomass in
12 days.
 Water covering plant.
 Deprives bottom water
of light & oxygen

13. Spotted knapweed
(Centaurea maculosa)
 A perennial
composite(Asterac
eae)
 Native of Eurasia
 Introduced in North
America in early
1900s accidentally
as seed
contaminant within
crop seed imports.
 it produces an
allelo chemical.
Knapweed infestation

14. .Japanese Stiltgrass
(Microstegium vimineum)
Alliaria petiolata
 Found in Crawford
country.
 Create ‘lawns’ in
forests.
 Displace native
herbaceous plants.
 Reduce biodiversity.
 outcompetes native
plants by monopolizing
light, moisture,
nutrients, soil and
space.
 It is allelopathic.

15.  Largest trees of
Eastern Deciduous
forest.
 A Chestnut-Blight
Fungus named
(Cryphonectria
parasitica) killed
them.
 It was introduced on
logs in 1909.
 By 1960n, Chestnut
had been rendered
functionally extinct.

16.  Native to China.
 Invasive
throughout the
U.S.A.
 Allelochemical
properties.
 Common in urban
areas(cause
damage to sewers
& structures).
 Threat to
cultivated fields.

17. Some invasive alien plants of India

18.  Various methods
involving-
 Administrative
methods
 Mechanical
methods
 Chemical
methods
 Biological
methods
Also involve strategies-
- alert local people
- give priority to eradication of
IAS.
- conduct more research.
- implement policies
concerning invasive species.

19. Conclusion
 Although, Intentionally introduced
plants have priority over native species
w.r.t. the household economy and
national economy.
 Invasive species threatens to native
species, habitats and ecosystem
functions and is economically costly.
 So, invasive species can be both boon
or bane to society. The relative
magnitude of losses & benefits vary
both in space and over time.

20. References
1. Ambasht, R.S., and Ambasht, N.K.2008. A
Textbook of Plant Ecology, CBS Publishers
& Distributers Pvt. Ltd., New Delhi.
2. Lerner, Brenda W. and Lerner, K.L.
Environmental Science-In Context(Vol.1).
Bejing, China.
3. Lockwood, L. Julie, Hoopes, F. Martha and
Marchetti, P. Michael(2007). Invasion
Ecology, 1st Edition. Blackwell Publishing
Ltd. U.K.
4. Singh, J.S, Singh, S.P. and Gupta, S.R.
(2010). Ecology, Environment and
Resource Conservation, 2nd Edition.
Anamaya Publishers, New Delhi.

21. Weblinks
 www.nepjol.info/index.php/HJS/article/download/
213/811
 www.nature.org/ourinitiatives/regions/...dc/.../mdi
nvasivebrochure
 www.arvindguptatoys.com/arvindgupta/invasivep
lants-1
 researchrepository.murdoch.edu.au/4635/1/delibera
te_introductions.
 related:www.orange.k12.oh.us/teachers/ohs/jsangdahl
/APESWEB/invasive%20species%20project2_files/inva
sive%20species%20project2.ppt invasive species ppt
 www.awcf1911.org/ONeill%20IS%20Impact%20O
neida%20Lake%2007.ppt invasive species ppt