Invasive species boon or bane, by manisha, m.sc(p) botany, roll no. 22
boon or bane
Class:- M.sc.(P) Botany
Roll no. 22
Characteristics of invasive species
Process of Invasion
Pathways of introduction
Impacts of invasive species
Native species:- occurring within their
Non-native species:- Introduced from
somewhere else into new area.
Also called Non-natives, Introduced sp. ,
Non-indigenous, Exotic sp. ,Alien sp. ,
Non-native organisms that cause, or have
the potential to cause, harm to the
environment, economies, or human health.
Wide geographic range
Highly successful seed dispersal, germination and
Alternative mode of reproduction
Have few natural predators, competitors, parasites
High cost of removal and control
Difficult to control or eliminate once established
statistical rule says that
1 in 10 of imported species become
1 in 10 of those introduced become
1 in 10 of those established becomes
All these stages have probability of
→10’s rule (Williamson & Filter, 1996)
Ecological, Economic, Human Health
it refers to the movement of organisms to a
new area for an express purpose i.e some
benefit is expected .
species that are transported as a byproduct
of movement of other goods.
Many nurseries &
Attached to fishing
gear, anchors, lines.
trade, pets, non-
Attached to ship
Underwater view of a highly
fouled ship hull showing
attached fouling organisms
Movement of species within
cargo load to
Some of them are:-
Invasive species can alter entire
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 .
Native of Asia
Invaded African rivers
Can double its biomass
every 2-3 days.
Carpet the surface of
water bodies with mats.
mosquitoes & snails.
Brought from South
Double its biomass in
Water covering plant.
Deprives bottom water
of light & oxygen
Native of Eurasia
Introduced in North
America in early
crop seed imports.
it produces an
Found in Crawford
Create ‘lawns’ in
plants by monopolizing
nutrients, soil and
It is allelopathic.
Largest trees of
It was introduced on
logs in 1909.
By 1960n, Chestnut
had been rendered
Native to China.
Common in urban
damage to sewers
Also involve strategies-
- alert local people
- give priority to eradication of
- conduct more research.
- implement policies
concerning invasive species.
Although, Intentionally introduced
plants have priority over native species
w.r.t. the household economy and
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.
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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).
3. Lockwood, L. Julie, Hoopes, F. Martha and
Marchetti, P. Michael(2007). Invasion
Ecology, 1st Edition. Blackwell Publishing
4. Singh, J.S, Singh, S.P. and Gupta, S.R.
(2010). Ecology, Environment and
Resource Conservation, 2nd Edition.
Anamaya Publishers, New Delhi.