Ecosystem EcologyEcosystem Ecology

the movement of materials and energy through an ecosystem

Section 22-1

Pages 415-419

Producers

• Manufacture their own food

• Capture energy and use it to make organic molecules

• There are two types:– Photosynthetic = use energy from light– Chemosynthetic = use energy from inorganic

chemicals

• Examples = plants, protists, and bacteria

Gross Primary Productivity

- is the rate at which producers in an ecosystem capture energy

Biomass

- is the organic material in an ecosystem

Sta

ndin

g C

rop

Bio

mas

s

Net Primary Productivity

= gross primary productivity – rate of respiration in producers

- is the rate at which biomass accumulates

- is expressed as: energy/area/year (kcal/m2/y) mass/area/year (g/m2/y)

Prim

ary

Pro

duct

ivity

of

Diff

eren

t Eco

syst

ems

Consumers• obtain energy by ingesting or consuming

organic molecules made by other organisms• grouped according to the food they eat

– Herbivores = eat producers– Carnivores = eat consumers– Omnivores = eat both producers and

consumers– Detritivores = eat garbage– Decomposers = break down dead tissues

and waste into smaller molecules

Movement of Stuff Through Ecosystems

Trophic Levels• an organism’s position in the

sequence of energy transfers• most ecosystems contain only

three or four trophic levelsProducers = 1st levelHerbivores = 2nd level

Carnivores = 3rd level +

Mov

emen

t of E

nerg

y

Food Chain

• a pathway of feeding relationships

Foo

d C

hain

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Gra

zing

Foo

d C

hain

Foo

d W

eb

Energy Movement & Nutrient Cycling

Pyr

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of N

et P

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ctio

n

Eco

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ffici

ency

Why is energy transfer so low?

• Energy is reflected.

• Energy is lost when some parts cannot be digested.

• Energy is lost as waste.

• Energy is lost in cellular respiration.

• Energy is lost as heat.

• Organisms die without being eaten.

Eco

logi

cal E

ffici

ency

100 * 3,368 / 20,810 = 17%

100 * 67 / 1478 = 4.5%

100 * 6 / 67 = 9%

Pyramid Shape• A diagram of trophic level

relationships• Width of bar correlates with the

number • Three primary types of diagrams

–Energy–Biomass–Population numbers

Bio

mas

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yram

ids

Pyr

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of N

umbe

rs

Eco

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iom

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