evs lecture ii 1 ecosystem

7/26/2019 EVS Lecture II 1 Ecosystem

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Eco System

M. Subramanian

Assistant Professor

Department of Chemical Engineering

Sri Sivasubramaniya Nadar College of Engineering

Kalavaam ! "#$ %%#& Kanchipuram 'Dist(

)amil Nadu& *ndia

msubbu.in+A),gmail.com

20-July-2009

GE 2211 Environmental Science and Engineering

Unit II

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Contents

- Concept of an ecosystem ! structure and function of anecosystem ! producers& consumers and decomposers !energy flo in the ecosystem ! ecological succession ! foodchains& food ebs and ecological pyramids

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*ntroduction

- An ecosystem can be defined as the basic

functional unit of nature& including both biotic'living( and abiotic 'nonliving( constituents.! a pond& a forest& an estuary& a grassland

- Abiotic components/ air& roc& and ater are thebasic components

- 0iotic components/ classified according to thefunction of the particular organism. )here arethree groups/! producers& consumers& and decomposers.


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Estuary


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Grassland20-July-2009 M Subramanian

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Ecosystems are not isolated from one another. Oneecosystem blends into the next through a transitional region,an ecotone, which contains many species common to the twoadjacent systems.


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Producers

- Producers! the green plants such as grasses and trees

! are so called because they are capable of producingtheir on food from the abiotic environment

- Producers create organic molecules proteins& lipids andcarbohydrates1 by capturing light energy and combining thecaptured energy ith inorganic molecules


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Consumers

- Consumers! organisms that are incapable of producing their on food and

that must use 'consume( other organisms for their food! all animals fall into this category.

! consumers feed on producers and ould not e2ist ithoutproducers.

- )hree types of consumers/! herbivores& hich eat plants 'producers(3

! carnivores& hich eat animals ! either herbivores or othercarnivores3

! omnivores& hich are both herbivorous and carnivorous.


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Decomposers

- Decomposers ! also called microconsumers& includebacteria& fungi& and some of the small invertebrates

'animals ithout bacbones & eg/ orms(.

- 4ie consumers& these organisms cannot produce their onfood3 but unlie consumers& they obtain their food energyby breaing don dead plants and animals to their basiccomponents& thereby releasing these substances bac intothe abiotic portions of the environment.


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5ood Chain


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5ood Chain in a Marine Ecosystem


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5ood 6ebs


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Marine 5ood 6eb


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Ecological Pyramid


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Ecological Succession

- Ecological succession is the gradual process by hichecosystems change and develop over time. Nothing

remains the same and habitats are constantly changing.

- Succession taes place because the environmentalconditions in a particular place change over time.

- Each species is adapted to thrive and compete best againstother species under a very specific set of environmentalconditions. *f these conditions change& then the e2istingspecies ill be replaced by a ne set of species hich are

better adapted to the ne conditions.


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Energy 5lo and Materials Cycling

The movement of nutrients (blue arrows) and energy (redarrows) and both (brown arrows) through the ecosystem.20-July-2009 M Subramanian

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Energy 5lo in Ecosystem


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Energy 5lo in Ecosystem

- Almost all life re7uires the energy that flos daily from the

sun.

- )he basic conversion of this solar energy to usable formtaes place through plant material on land and in ater.

- As the energy passes from plants to hatever eats them&and in turn eats the eaters of the plants& some is lost asheat& and eventually it all is.

- )hus& energy doesn8t cycle3 it flos through the ecosystemuntil it8s used up.


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6ater Cycle


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Mineral Cycle


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Carbon Cycle


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CO2

PRODUCERS

taken up during

photosynthesis

1st CONSUMERS

2nd CONSUMERS

3rd CONSUMERS

DECOMPOSERS

Cellular respiration

releases

Food web subcycle

Decomposition releases

C compounds into soil


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Fossil fuel

subcycle

CO2

FOOD WEB

SUBCYCLE

dead organisms buried

by sediment become

FOSSIL FUELS


releases photosynthesisBurning

releases


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CO2

FOOD WEB

SUBCYCLE

dead organisms buried

by sediment become

FOSSIL FUELS


releases photosynthesisBurning

of fossil fuels

increases CO2levels

shells and skeletons of marine

organisms deposited and

compressed to become

CARBONATE ROCKSDecompose (weather)

into bicarbonate ion (HCO3-

)

further decomposition

produces

Ion in water enters

Where human activities change the cycling rate of carbon

among reservoirs.

Removal of vegetation

(trees) prevents CO2

from being removedfrom the atmosphere


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Carbon Cycle


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Nitrogen Cycle


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Atmosphere

N2 (g)

Soil moisture

dissolves in

Dissolved N2

absorbed by

N-fixing bacteriaLeguminous bacteria

Legumes (plants)

symbiosisNO

3

-- released in roots,

absorbed by

Nitrifying bacteria

NH3absorbed by

Consumers

Organic nitrogen

ingested by NH3 produced as

waste from breakdown

of proteins

All plants

NO3-- in soilabsorbed by

Denitrifying bacteria

(under anaerobic

conditions)

N2 (g)

released into

Atmospheric fixation

generates nitric acid(HNO3)

HNO3 dissociates in

soil

Nitrogen Cycle


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Phosphorus Cycle


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evs lecture ii 1 ecosystem

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