ECOSYSTEM ECOLOGY Energy Flow food chains Ecosystem The

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ECOSYSTEM ECOLOGY : Energy Flow, food chains

ECOSYSTEM ECOLOGY : Energy Flow, food chains

Ecosystem: • The organisms in a particular area and the physical environment with which

Ecosystem: • The organisms in a particular area and the physical environment with which they interact. • All the biotic and abiotic factors in a community. (Abiotic factors: energy, water, carbon, nitrogen, phosphorous)

An ecosystem has abiotic and biotic components: • ABIOTIC components: • Solar energy provides

An ecosystem has abiotic and biotic components: • ABIOTIC components: • Solar energy provides practically all the energy for ecosystems. • Inorganic substances, e. g. , sulfur, boron, tend to cycle through ecosystems.

 • BIOTIC components: • The biotic components of an ecosystem can be classified

• BIOTIC components: • The biotic components of an ecosystem can be classified according to their mode of energy acquisition. • In this type of classification, there are: • Autotrophs

Autotrophs • Autotrophs (=self-nourishing) are called primary producers. • Photoautotrophs fix energy from the

Autotrophs • Autotrophs (=self-nourishing) are called primary producers. • Photoautotrophs fix energy from the sun and store it in complex organic compounds light • (= green plants, algae, some complex organic photoautotrophs bacteria) simple inorganic compounds

 • Chemoautotrophs (chemosynthesizers) are bacteria • that oxidize reduced inorganic substances • (typically

• Chemoautotrophs (chemosynthesizers) are bacteria • that oxidize reduced inorganic substances • (typically sulfur and ammonia compounds) • and produce complex organic compounds. oxygen reduced inorganic compounds chemoautotrophs complex organic compounds

Chemosynthesis near hydrothermal vents

Chemosynthesis near hydrothermal vents

Other chemoautotrophs: Nitrifying bacteria in the soil under our feet!

Other chemoautotrophs: Nitrifying bacteria in the soil under our feet!

Heterotrophs • Heterotrophs (=other-nourishing) cannot produce their own food directly from sunlight+ inorganic compounds.

Heterotrophs • Heterotrophs (=other-nourishing) cannot produce their own food directly from sunlight+ inorganic compounds. They require energy previously stored in complex molecules. organic heterotrophs compounds (this may include several steps, with several different types of organisms) heat simple inorganic compounds

 • Heterotrophs can be grouped as: • • consumers • decomposers

• Heterotrophs can be grouped as: • • consumers • decomposers

 • Consumers feed on organisms or particulate organic matter. • Decomposers utilize complex

• Consumers feed on organisms or particulate organic matter. • Decomposers utilize complex compounds in dead protoplasm. • Bacteria and fungi are the main groups of decomposers. • Bacteria are the main feeders on animal material.

Fig. 55 -4 Tertiary consumers Microorganisms and other detritivores Detritus Secondary consumers Primary producers

Fig. 55 -4 Tertiary consumers Microorganisms and other detritivores Detritus Secondary consumers Primary producers Heat Key Chemical cycling Energy flow Sun

Energy Flow through Ecosystems • Energy flows through ecosystems as organisms capture and store

Energy Flow through Ecosystems • Energy flows through ecosystems as organisms capture and store energy, then transfer it to organisms that eat them. • These organisms are grouped into trophic levels. . .

Trophic Levels: Route of energy flow - food chain - food web - pyramid

Trophic Levels: Route of energy flow - food chain - food web - pyramid of numbers

Pyramid of Numbers

Pyramid of Numbers

Question: “Why are big fierce animals rare? ” Charles Elton, 1927

Question: “Why are big fierce animals rare? ” Charles Elton, 1927

Answer: Because of the way energy flows through communities. . .

Answer: Because of the way energy flows through communities. . .

Ecosystem Energy Budgets: Primary Productivity (PP) Secondary Productivity (SP 1, SP 2)

Ecosystem Energy Budgets: Primary Productivity (PP) Secondary Productivity (SP 1, SP 2)

Primary Productivity (PP) • Rate at which energy or biomass is produced per unit

Primary Productivity (PP) • Rate at which energy or biomass is produced per unit area by plants (primary producers) • Photosynthesis powers primary productivity. • The annual productivity of an area is determined primarily by sunlight, temperature, and moisture.

Distribution of Primary Production Worldwide Figure 56. 5

Distribution of Primary Production Worldwide Figure 56. 5

Positive Correlation Between Productivity and Sunlight

Positive Correlation Between Productivity and Sunlight

Positive Correlation Between Productivity and. . . Precipitation Temperature

Positive Correlation Between Productivity and. . . Precipitation Temperature

Fig. 55 -8 Net primary production (g/m 2·yr) · 3, 000 Tropical forest 2,

Fig. 55 -8 Net primary production (g/m 2·yr) · 3, 000 Tropical forest 2, 000 Temperate forest 1, 000 Mountain coniferous forest Desert shrubland 0 Temperate grassland Arctic tundra 0 500 1, 000 Actual evapotranspiration (mm H 2 O/yr)

Secondary Productivity (SP 1, SP 2…) • rate of production of new biomass from

Secondary Productivity (SP 1, SP 2…) • rate of production of new biomass from PP by heterotrophic organisms (primary and secondary consumers) • positively correlated with rainfall. . .

Fig. 55 -10 Tertiary consumers Secondary consumers 10 J 100 J Primary consumers 1,

Fig. 55 -10 Tertiary consumers Secondary consumers 10 J 100 J Primary consumers 1, 000 J Primary producers 10, 000 J 1, 000 J of sunlight

Where does all the energy go? ? ?

Where does all the energy go? ? ?

Fig. 55 -9 Plant material eaten by caterpillar 200 J 67 J Feces 100

Fig. 55 -9 Plant material eaten by caterpillar 200 J 67 J Feces 100 J 33 J Growth (new biomass) Cellular respiration

Ecological Efficiency: Percent of energy transferred from one trophic level to the next.

Ecological Efficiency: Percent of energy transferred from one trophic level to the next.

Three categories of transfer efficiency are required to predict energy flow from PP to

Three categories of transfer efficiency are required to predict energy flow from PP to SP 1 to SP 2. . . 1) consumption efficiency 2) assimilation efficiency 3) production efficiency

1) consumption efficiency (CE) % of total productivity at one trophic level that is

1) consumption efficiency (CE) % of total productivity at one trophic level that is consumed by the next highest level (remainder not eaten)

Green World Hypothesis • Plants have many defenses against herbivores

Green World Hypothesis • Plants have many defenses against herbivores

2) assimilation efficiency (AE) % of ingested food energy that is assimilated (i. e.

2) assimilation efficiency (AE) % of ingested food energy that is assimilated (i. e. digested), and thus potentially available for growth, reproduction (remainder lost as feces)

Elephant dung

Elephant dung

3) production efficiency (PE) % of assimilated energy that is incorporated into new biomass

3) production efficiency (PE) % of assimilated energy that is incorporated into new biomass (growth, reproduction) (remainder lost as respiratory heat)

Implications? • SP 1 is the % of PP that is incorporated at the

Implications? • SP 1 is the % of PP that is incorporated at the next highest trophic level. (Ditto for SP 2…) This is NEVER 100%. • Thus, energy loss at each trophic level limits the length of a food chain. . .

And that is why big fierce animals are rare!

And that is why big fierce animals are rare!

Biogeochemical Cycles Nutrients exist in pools of chemical elements FOUR main reservoirs where these

Biogeochemical Cycles Nutrients exist in pools of chemical elements FOUR main reservoirs where these nutrients exist are: 1) Atmosphere - carbon in carbon dioxide, nitrogen in atmospheric nitrogen 2) Lithosphere - the rocks - phosphates, calcium in calcium carbonate, potassium in feldspar 3) Hydrosphere - the water of oceans, lakes, streams and soil - nitrogen in dissolved nitrate, carbon in carbonic acid

Atmosphere Living Organisms + Detritus Lithosphere Hydrosphere

Atmosphere Living Organisms + Detritus Lithosphere Hydrosphere

4) Living Organisms and Nutrient Cycles • Living organisms are a reservoir in which

4) Living Organisms and Nutrient Cycles • Living organisms are a reservoir in which carbon exists in carbohydrates (mainly cellulose) and fats, nitrogen in protein, and phosphorus in ATP

 • In studying cycling of water, carbon, nitrogen, and other chemicals, ecologists focus

• In studying cycling of water, carbon, nitrogen, and other chemicals, ecologists focus on four factors: – Biological importance of each chemical – Major reservoirs for each chemical – Forms in which each chemical is available or used by organisms – Key processes driving movement of each chemical through its cycle

The Water Cycle • Water is essential to all organisms • 97% of the

The Water Cycle • Water is essential to all organisms • 97% of the biosphere’s water is contained in the oceans, 2% is in glaciers and polar ice caps, and 1% is in lakes, rivers, and groundwater • Water moves by the processes of evaporation, transpiration, condensation, precipitation, and movement through surface and groundwater

The Carbon Cycle • Carbon-based organic molecules are essential to all organisms • Carbon

The Carbon Cycle • Carbon-based organic molecules are essential to all organisms • Carbon reservoirs include fossil fuels, soils and sediments, solutes in oceans, plant and animal biomass, and the atmosphere • CO 2 is taken up via photosynthesis and released via respiration • Volcanoes and the burning of fossil fuels contribute CO 2 to the atmosphere

Fig. 55 -21 14. 9 390 14. 8 380 14. 7 CO 2 concentration

Fig. 55 -21 14. 9 390 14. 8 380 14. 7 CO 2 concentration (ppm) Temperature 14. 5 360 14. 4 14. 3 350 14. 2 340 14. 1 CO 2 330 14. 0 13. 9 320 13. 8 310 300 13. 7 13. 6 1960 1965 1970 1975 1980 1985 Year 1990 1995 2000 2005 Average global temperature (ºC) 14. 6 370

… and Global Temperature

… and Global Temperature

The Nitrogen Cycle • Nitrogen is a component of amino acids, proteins, and nucleic

The Nitrogen Cycle • Nitrogen is a component of amino acids, proteins, and nucleic acids • The main reservoir of nitrogen is the atmosphere (N 2) • N 2 is converted to NH 3 via nitrogen-fixing bacteria • Organic nitrogen is decomposed to NH 4+ by ammonification, and NH 4+ is decomposed to NO 3– by nitrifying bacteria; NH 4+ and NO 3– assimilated by plants • Denitrifying bacteria convert NO 3– back to N 2

How Bears Feed Salmon to the Forest • The run of salmon leads to

How Bears Feed Salmon to the Forest • The run of salmon leads to a major flow of nutrients into estuaries and coastal watersheds

 • Bears catch salmon in river and consume them in forest; on average,

• Bears catch salmon in river and consume them in forest; on average, half the carcass is not eaten. • Bears’ fat tissue is virtually nitrogen-free, so most of nitrogen in salmon protein is excreted as urine and feces.

 • Nitrogen 14 from atmosphere • Nitrogen 15 from salmon • Measurements of

• Nitrogen 14 from atmosphere • Nitrogen 15 from salmon • Measurements of nitrogen isotope ratios in tree rings shows that nitrogen from salmon is incorporated into trees and enhances their growth