Invasive species: boon or bane

Submitted by:-

ManishaClass:- M.sc.(P) BotanyRoll no. 22

Contents Introduction Characteristics of invasive species Invasion Rule Process of Invasion Pathways of introduction

Deliberate Accidental

Impacts of invasive species Examples Controlling measures Conclusion References

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.

Characteristics of invasive species 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

Invasion rulestatistical rule says that 1 in 10 of imported species become

introduced1 in 10 of those introduced become

established1 in 10 of those established becomes a

pestAll these stages have probability of

≈10%→10’s rule (Williamson & Filter,

1996)

Steps involved in Invasion

.Transport Introduction

Establishment Spread

Impact

Ecological, Economic, Human Health

Pathways of introductionDeliberately 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.

Intentional transport

For FoodGame speciesBio-controlOrnamental

plantsEnvironmental

enhancementConservation &

Scientific persuitesMany nurseries &

hobbyists

Unintentional transportAs 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 highlyfouled ship hull showing attached fouling organisms

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.

Impacts of invasive species

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 .

ExamplesRed Water Fern, Azolla 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

Spotted knapweed(Centaurea maculosa)

A perennial composite(Asteraceae)

Native of EurasiaIntroduced in

North America in early 1900s accidentally as seed contaminant within crop seed imports.

it produces an allelo chemical.

Knapweed infestation

.Japanese Stiltgrass(Microstegium vimineum)

Garlic MustardAlliaria 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.

American ChestnutLargest 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.

Tree of Heaven(Ailanthus altissima)

Native to China.Invasive

throughout the U.S.A.

Allelochemical properties.

Common in urban areas(cause damage to sewers & structures).

Threat to cultivated fields.

Some invasive alien plants of India

Controlling MeasuresVarious 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.

ConclusionAlthough, 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.

References1. 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.

Weblinkswww.nepjol.info/index.php/HJS/article/download/2

13/811www.nature.org/ourinitiatives/regions/...dc/.../md

invasivebrochurewww.arvindguptatoys.com/arvindgupta/

invasiveplants-1researchrepository.murdoch.edu.au/4635/1/

deliberate_introductions.related:www.orange.k12.oh.us/teachers/ohs/

jsangdahl/APESWEB/invasive%20species%20project2_files/invasive%20species%20project2.ppt invasive species ppt

www.awcf1911.org/ONeill%20IS%20Impact%20Oneida%20Lake%2007.ppt invasive species ppt

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