IB Environmental systems and societies Topic 2.2G Ecological Pyramids Revision Notes (SL/HL)

IB Environmental systems and societies Topic 2.2G Ecological Pyramids Revision Notes (SL/HL) | RevisionDojo

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Ecological Pyramids: The Same Ecosystem Can Look Different Depending on What You Count

Definition

Ecological pyramids

Ecological pyramids are graphical representations used to show the relative numbers, biomass, or energy at different trophic levels in an ecosystem.

An ecological pyramid is a graphical model of the quantitative differences between trophic levels in an ecosystem.
Each bar sits at a trophic level, with producers at the base and consumers stacked above them.
The width of each bar shows how much of the counted quantity is present at that level.
The three types differ only in what they count: numbers, biomass, or energy.

The Three Types of Ecological Pyramid

Pyramid of numbers: counts the number of individual organisms at each trophic level in a defined area.
1. It gives a snapshot of population sizes at one moment in time.
Pyramid of biomass: shows the total dry mass of organisms at each level at one moment, called the standing crop.
1. Units are usually g m⁻² or kg m⁻².
Pyramid of energy: shows the rate of energy flow through each trophic level over time.
1. Units are usually kJ m⁻² yr⁻¹.

Hint

Numbers and biomass pyramids show a standing crop measured at a single instant.
The energy pyramid shows a rate, energy per unit area per unit time.

Pyramid of Numbers

In most ecosystems the pyramid of numbers narrows toward the top, because fewer individuals are supported at each higher level.
This upright shape follows the loss of energy along the food chain, so less energy supports fewer organisms higher up.
The pyramid of numbers can be inverted when a few large producers support many small consumers.
1. A single oak tree supports thousands of insects, which puts a wide bar above a narrow one.

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Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

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Note

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Excepteur sint occaecat cupidatat non proident

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Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

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Ecological Pyramids: The Same Ecosystem Can Look Different Depending on What You Count

Definition

Ecological pyramids

Ecological pyramids are graphical representations used to show the relative numbers, biomass, or energy at different trophic levels in an ecosystem.

An ecological pyramid is a graphical model of the quantitative differences between trophic levels in an ecosystem.
Each bar sits at a trophic level, with producers at the base and consumers stacked above them.
The width of each bar shows how much of the counted quantity is present at that level.
The three types differ only in what they count: numbers, biomass, or energy.

The Three Types of Ecological Pyramid

Pyramid of numbers: counts the number of individual organisms at each trophic level in a defined area.
1. It gives a snapshot of population sizes at one moment in time.
Pyramid of biomass: shows the total dry mass of organisms at each level at one moment, called the standing crop.
1. Units are usually g m⁻² or kg m⁻².
Pyramid of energy: shows the rate of energy flow through each trophic level over time.
1. Units are usually kJ m⁻² yr⁻¹.

Hint

Numbers and biomass pyramids show a standing crop measured at a single instant.
The energy pyramid shows a rate, energy per unit area per unit time.

Pyramid of Numbers

In most ecosystems the pyramid of numbers narrows toward the top, because fewer individuals are supported at each higher level.
This upright shape follows the loss of energy along the food chain, so less energy supports fewer organisms higher up.
The pyramid of numbers can be inverted when a few large producers support many small consumers.
1. A single oak tree supports thousands of insects, which puts a wide bar above a narrow one.

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

Topic 1: Foundation 3 subtopics

Topic 2: Ecology5 subtopics

Topic 3: Conservation and biodiversity3 subtopics

Topic 4: Water4 subtopics

Topic 5: Land2 subtopics

Topic 6: Atmosphere and climate change4 subtopics

Topic 7: Natural resources3 subtopics

Topic 8: Human populations and urban systems3 subtopics

HL lenses 3 subtopics

IB Environmental systems and societies 2.2G Ecological Pyramids Notes

Ecological Pyramids: The Same Ecosystem Can Look Different Depending on What You Count

The Three Types of Ecological Pyramid

Pyramid of Numbers

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Ecological Pyramids: The Same Ecosystem Can Look Different Depending on What You Count

The Three Types of Ecological Pyramid

Pyramid of Numbers

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Topic 1: Foundation 3 subtopics

Topic 2: Ecology5 subtopics

Topic 3: Conservation and biodiversity3 subtopics

Topic 4: Water4 subtopics

Topic 5: Land2 subtopics

Topic 6: Atmosphere and climate change4 subtopics

Topic 7: Natural resources3 subtopics

Topic 8: Human populations and urban systems3 subtopics

HL lenses 3 subtopics