ecology 4 - pyramid of numbers and biomass
DESCRIPTION
Ecology 4 - Pyramid of Numbers and BiomassTRANSCRIPT
![Page 1: Ecology 4 - Pyramid of Numbers and Biomass](https://reader036.vdocument.in/reader036/viewer/2022080220/55cf9bce550346d033a7722b/html5/thumbnails/1.jpg)
Topic Outline
• Ecology
• Population,
community and
ecosystem
• Biotic and abiotic
environment
• Relationships
• Food chain and web
• Energy transfer
between trophic
levels
• Carbon cycle
• Pyramid of numbers
and biomass
• Water pollution
• Conservation and
biodiversity
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ECOLOGY
Pyramids of
energy, numbers
and biomass
![Page 3: Ecology 4 - Pyramid of Numbers and Biomass](https://reader036.vdocument.in/reader036/viewer/2022080220/55cf9bce550346d033a7722b/html5/thumbnails/3.jpg)
Lesson Outline
• Pyramid of energy
• Pyramid of numbers
• Pyramid of biomass
![Page 4: Ecology 4 - Pyramid of Numbers and Biomass](https://reader036.vdocument.in/reader036/viewer/2022080220/55cf9bce550346d033a7722b/html5/thumbnails/4.jpg)
Ecological Pyramids
• Pyramid of energy – shows energy flow through the trophic levels of a
food chain.
• Pyramid of numbers – shows the number of organisms at each trophic
level at a particular time.
• Pyramid of biomass – shows the mass of organisms at each trophic level
at a particular time.
![Page 5: Ecology 4 - Pyramid of Numbers and Biomass](https://reader036.vdocument.in/reader036/viewer/2022080220/55cf9bce550346d033a7722b/html5/thumbnails/5.jpg)
Pyramid of energy
• shows energy flow through the trophic
levels of a food chain.
![Page 6: Ecology 4 - Pyramid of Numbers and Biomass](https://reader036.vdocument.in/reader036/viewer/2022080220/55cf9bce550346d033a7722b/html5/thumbnails/6.jpg)
Pyramid of numbers
• shows the number of organisms at each
trophic level at a particular time.
![Page 7: Ecology 4 - Pyramid of Numbers and Biomass](https://reader036.vdocument.in/reader036/viewer/2022080220/55cf9bce550346d033a7722b/html5/thumbnails/7.jpg)
Pyramid of numbers
• Consider the following food chain:
• If there is 1 lion in an area and it feeds on 7
giraffes in a month.
• Each giraffe feeds on 2 trees in a month.
• What would a pyramid of numbers look
like?
tree giraffe lion
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Pyramid of numbers
• This pyramid is broad
at the bottom and
narrow towards the
top.
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Pyramid of biomass
• Consider the following food chain:
• Biomass of 1 lion = 20kg
• Biomass of 1 giraffe = 20kg
• Biomass of 1 tree = 30kg
• What would a pyramid of biomass look like?
tree giraffe lion
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Pyramid of biomass
• For this food chain,
the pyramid of
biomass has a similar
shape to the pyramid
of numbers.
![Page 11: Ecology 4 - Pyramid of Numbers and Biomass](https://reader036.vdocument.in/reader036/viewer/2022080220/55cf9bce550346d033a7722b/html5/thumbnails/11.jpg)
Worksheet time
• Let’s try constructing our own pyramids!
• Pyramids need not always be broad at the
bottom and narrow at the top!
– Use rectangles.
– Producers are always at the bottom,
consumers at the top.
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Grass rabbit snake hawk
Pyramid of numbers Pyramid of biomass
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Tree aphid protozoa
Pyramid of numbers Pyramid of biomass
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Tree aphid ladybird small bird
Pyramid of numbers Pyramid of biomass
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grass zebra tsetse fly
Pyramid of numbers Pyramid of biomass
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Comparison – which pyramid to use?
• If the producer is a large plant, then the second layer of the pyramid will be much larger than the base.
• It would make more sense to draw a pyramid of biomass
A pyramid of
numbers
A pyramid of
biomass
![Page 17: Ecology 4 - Pyramid of Numbers and Biomass](https://reader036.vdocument.in/reader036/viewer/2022080220/55cf9bce550346d033a7722b/html5/thumbnails/17.jpg)
Conclusion
• Pyramids of biomass are a more accurate
representation of the food chain.
• Pyramids of biomass (almost) always have
a broader base and narrower tip.
– What is the exception?
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References
• http://www.globalchange.umich.edu/gctext/I
nquiries/Inquiries_by_Unit/Unit_4.htm