Chapter54AEcosystems.ppt

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Ch. 54 Warm-Up

1. Draw an energy pyramid and

label the following trophic levels:

▫ Primary producer

▫ Primary consumer

▫ Secondary consumer

▫ Tertiary consumer

2. What is an example of an

organism at each level of the pyramid in #1?

3. If 5000 J of energy is available in

producers, how much of that energy would be available to tertiary consumers?

Define Ch. 54 Terms:

 _Autotroph  _Heterotroph  Detritivore

 _{Gross primary}

production (GPP)

 _{Net primary production}

(NPP)

 Eutrophication

 _{Biogeochemical cycle}  _{Nitrogen fixation}

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You Must Know:

•How energy flows through the ecosystem (food chains and food webs)

•The difference between gross primary productivity and net primary productivity.

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Ecosystems

Ecosystem = sum of all the organisms living

within its boundaries (biotic community) + abiotic factors with which they interact

Involves two unique processes:

1. Energy flow

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Microorganisms and other detritivores

Tertiary consumers

Secondary consumers

Detritus Primary consumers

Sun

Primary producers

Heat Key

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Trophic Structures

•The trophic structure of a community is

determined by the feeding relationships between organisms.

•Trophic levels = links in the trophic structure

•The transfer of food energy from plants 

herbivores  carnivores  decomposers is called

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Fig. 53.10

What limits the length of a food chain?

•Energetic hypothesis

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•Two or more food chains linked together are called

food webs.

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Energy Flow in an Ecosystem

•Energy cannot be recycled  must be constantly

supplied to an ecosystem

•SUN_SUN = energy

•The autotrophs (“self feeders”) are the primary

producers, and are usually photosynthetic (plants or algae).

▫They use light energy to synthesize sugars and other organic compounds.

•Heterotrophs (“other feeders”) – can’t make own

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•Heterotrophs are at trophic levels above the primary producers and

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▫

Herbivores that eat primary producers are

called

primary consumers

.

▫

Carnivores that eat herbivores are called

secondary consumers

.

▫

Carnivores that eat secondary producers are

called

tertiary consumers

.

▫

Another important group of heterotrophs is the

detritivores

, or

decomposers

.



_{They get energy from detritus, nonliving}

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▫Main decomposers: fungi and prokaryotes

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Primary Production

•Total primary production is known as gross

primary production (GPP).

▫This is the amount of light energy that is converted into chemical energy.

•The net primary production (NPP) is equal to

gross primary production minus the energy used by the primary producers for respiration (R):

▫NPP = GPP – R

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Open ocean Continental shelf

Upwelling zones Extreme desert, rock, sand, ice

Swamp and marsh Lake and stream Desert and semidesert scrub Tropical rain forest

Temperate deciduous forest Temperate evergreen forest Tropical seasonal forest Savanna Cultivated land Estuary Algal beds and reefs

Boreal forest (taiga) Temperate grassland Woodland and shrubland Tundra 0.4 0.4 1.0 1.3 1.5 1.6 1.7 1.8 2.4 2.7 2.9 3.3 3.5 4.7 0.3 0.1 0.1 5.2 65.0

Freshwater (on continents) Terrestrial

Marine

Key _{Percentage of Earth’s} surface area

Average net primary production (g/m2_/yr)

60 50 40 30 20 10

0 0 500 1,0001,5002,0002,500

Percentage of Earth’s net primary production 25 20 15 10 5 0 125 2,500 360 1,500 500 3.0 90 900 600 800 2,200 600 250 1,600 1,200 1,300 2,000 700 140 0.3 7.9 9.1 9.6 5.4 3.5 0.6 7.1 4.9 3.8 2.3 24.4 5.6 1.2 0.9 0.1 0.04 0.9 22

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•Primary production affected by:

▫_{Light availability (↑ depth, ↓ photosynthesis)} ▫Nutrient availability (N, P in marine env.)

•Key factors controlling primary production:

▫Temperature & moisture

•A nutrient-rich lake that supports algae growth is

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Energy transfer between trophic levels is

typically only 10% efficient

Growth (new biomass)

Cellular respiration Feces 100 J

33 J

67 J 200 J

Plant material eaten by caterpillar

•Production efficiency: only fraction of E stored in food

•Energy used in

respiration is lost as heat

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1,000,000 J of sunlight 10,000 J

1,000 J 100 J 10 J Tertiary

consumers

Primary consumers

Primary producers

10% transfer of energy from one

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Pyramids of energy or biomass or numbers

gives insight to food chains

Pyramid of Numbers

Pyramid of Biomass

• Loss of energy limits # of top-level carnivores

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Trophic level

Primary producers

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Matter Cycles in Ecosystem

•Biogeochemical cycles: nutrient cycles that

contain both biotic and abiotic components

•organic  inorganic parts of an ecosystem

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Fossilization

Reservoir a Reservoir b

Reservoir c Reservoir d

Organic materials available as nutrients Organic materials unavailable as nutrients Inorganic materials available as nutrients Inorganic materials unavailable as nutrients Living organisms, detritus Coal, oil, peat Atmosphere, soil, water Minerals in rocks Assimilation, photosynthesis _Burning

of fossil fuels

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Water Cycle

Transport over land

Precipitation over land Evaporation

from ocean Precipitation

over ocean

Net movement of water vapor by wind

Solar energy

Evapotranspiration from land

Runoff and groundwater

(23)

Cellular respiration

Burning of fossil fuels and wood

Carbon compounds in water

Photosynthesis

Higher-level consumers

Detritus

Decomposition

CO₂ in atmosphere

Carbon Cycle

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Assimilation N₂ in atmosphere

Decomposers Nitrifying bacteria Nitrifying bacteria Nitrogen-fixing soil bacteria Denitrifying bacteria Nitrification Ammonification Nitrogen-fixing bacteria in root nodules of legumes

NO₃–

NO₂– NH₄+

NH₃

Nitrogen Cycle

• Nitrogen fixation:

▫ N₂  plants by bacteria

• Nitrification:

▫ ammonium  nitrite 

nitrate

▫ Absorbed by plants

• Denitrification:

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Phosphorus Cycle

Sedimentation

Plants Rain

Runoff Weathering of rocks Geologic

uplift

Soil Leaching

Decomposition Plant uptake of PO₄3–