Ecosystems

• MAYURBHANJ SCHOOL OF ENGINEERING
• SUBJECT- ENVIRONMENTAL STUDIES
• FACULTY NAME- MR R K BEHERA
• SEMESTER- 3^RD
• TOPIC- ENVIRONMENTAL STUDIES
• ECOSYSTEM

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STUDYING ORGANISMS IN THEIR ENVIRONMENT

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biosphere

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ecosystem

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community

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population

organism

ESSENTIAL QUESTIONS

• What limits the production in ecosystems?
• How do nutrients move in the ecosystem?
• How does energy move through the ecosystem?

ECOSYSTEM

• All the organisms in a community plus abiotic factors
• ecosystems are transformers of energy �& processors of matter
• Ecosystems are self-sustaining
• what is needed?

• capture energy
• transfer energy
• cycle nutrients

ECOSYSTEM INPUTS

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biosphere

constant input�of energy

energy flows�through

nutrients cycle

nutrients� can only �cycle

inputs

• energy
• nutrients

Don’t forget�the laws of �Physics!

Matter cannot

be created or�destroyed

GENERALIZED NUTRIENT CYCLING

consumers

decomposers

abiotic�reservoir

nutrients�made available�to producers

geologic�processes

consumers

consumers

producers

decomposers

abiotic�reservoir

nutrients�ENTER FOOD CHAIN�= made available�to producers

geologic�processes

return to�abiotic�reservoir

CARBON CYCLE

abiotic reservoir:

• CO₂ in atmosphere

enter food chain:

• photosynthesis = carbon fixation in Calvin cycle

recycle:

return to abiotic:

• respiration
• combustion

NITROGEN CYCLE

Birds

Herbivores

Plants

amino acids

Carnivores

Atmospheric

nitrogen

loss to deep sediments

Fish

Plankton with

nitrogen-fixing

bacteria

Nitrogen-fixing

bacteria

(plant roots)

Nitrogen-fixing

bacteria

(soil)

Denitrifying

bacteria

Death, excretion, feces

Nitrifying bacteria

soil nitrates

excretion

Decomposing bacteria

Ammonifying bacteria

abiotic reservoir:

• N in atmosphere

enter food chain:

• nitrogen fixation by soil & aquatic bacteria

recycle:

• decomposing & nitrifying bacteria

return to abiotic:

• denitrifying bacteria

PHOSPHORUS CYCLE

Loss to deep sediment

Rocks and

minerals

Soluble soil

phosphate

Plants and

algae

Plants

Urine

Land

animals

Precipitates

Aquatic

animals

Animal tissue

and feces

Animal tissue

and feces

Decomposers

(bacteria and

fungi)

Decomposers

(bacteria & fungi)

Phosphates

in solution

Loss in

drainage

abiotic reservoir:

• rocks, minerals, soil

enter food chain:

• erosion releases soluble phosphate
• uptake by plants

recycle:

• decomposing bacteria & fungi

return to abiotic:

• loss to ocean sediment

Lakes

Runoff

Percolation in soil

Evaporation

Transpiration

Precipitation

Oceans

Solar energy

Aquifer

Groundwater

Water cycle

Water vapor

abiotic reservoir:

• surface & atmospheric water

enter food chain:

• precipitation & plant uptake

recycle:

• transpiration

return to abiotic:

• evaporation & runoff

TRANSPIRATION

Remember�transpiration?

BREAKING THE WATER CYCLE

• Deforestation breaks the water cycle
• groundwater is not transpired to the atmosphere, so precipitation is not created

forest → desert

desertification

REPAIRING THE DAMAGE

• The Greenbelt Movement
• planting trees in Kenya
• restoring a sustainable ecosystem
• establishing democracy
• empowering women

Nobel Peace prize 2004

STUDYING ECOSYSTEMS

Hubbard Brook Experimental Forest

38 acre deforestation

EFFECTS OF DEFORESTATION

Concentration

of nitrate (mg/l )

1965

1966

Year

2

0

4

40

80

1967

1968

Deforestation

nitrate levels in runoff

40% increase in runoff

• loss of water

• 60x loss in nitrogen
• 10x loss in calcium

loss into �surface water

loss out of �ecosystem!

Why is�nitrogen so�important?

ECOSYSTEM INPUTS

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biosphere

energy flows�through

nutrients cycle

inputs

• energy
• nutrients

ENERGY FLOWS THROUGH ECOSYSTEMS

sun

producers (plants)

secondary �consumers

(carnivores)

primary consumers

(herbivores)

FOOD CHAINS

• Trophic levels
• feeding relationships
• start with energy from �the sun
• captured by plants
• 1^st level of all food chains
• food chains usually go �up only 4 or 5 levels
• inefficiency of energy transfer
• all levels connect to decomposers

Fungi

Level 4

Level 3

Level 2

Level 1

Decomposers

Producer

Primary consumer

Secondary consumer

Tertiary consumer

top carnivore

carnivore

herbivore

Bacteria

autotrophs

heterotrophs

sun

INEFFICIENCY OF ENERGY TRANSFER

• Loss of energy between levels of food chain
• To where is the energy lost? The cost of living!

only this energy�moves on to the� next level in �the food chain

17%

growth

50%

waste (feces)

33%

cellular

respiration

sun

ECOLOGICAL PYRAMID

• Loss of energy between levels of food chain
• can feed fewer animals in each level

1,000,000,000

100,000

100

1

sun

HUMANS IN FOOD CHAINS

• Dynamics of energy through ecosystems have important implications for human populations
• how much energy does it take to feed a human?
• if we are meat eaters?
• if we are vegetarian?

What is your�ecological �footprint?!

FOOD WEBS

• Food chains are linked together into food webs
• Who eats whom?
• a species may weave into web at more than one level
• bears
• humans
• eating meat?
• eating plants?

THANK YOU