Chapter 54 ecosystems
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Chapter 54 Ecosystems. Ecosystem. All the organisms and abiotic factors in a community. Ecosystem Studies. 1. Energy Flow – the movement of energy through trophic levels. 2. Chemical Cycling – the movement of matter from one part of the ecosystem to another. Trophic Levels.

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Chapter 54 Ecosystems

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Chapter 54 Ecosystems


Ecosystem

  • All the organisms and abiotic factors in a community.


Ecosystem Studies

1. Energy Flow – the movement of energy through trophic levels.

2. Chemical Cycling – the movement of matter from one part of the ecosystem to another.


Trophic Levels

  • Division of an ecosystem based on the source of nutrition (energy).


Trophic Levels

1. Primary Producers

2. Primary Consumers

3. Secondary Consumers

4. Detritivores


Primary Producers

  • Usually plants, capture energy and store it in chemical bonds.

  • Are the source of the energy available to an ecosystem.


Primary Consumers

  • Organisms that feed on the producers.

  • Ex: Herbivores


Secondary Consumers

  • Organisms that feed on the Primary Consumers.

  • Ex: Carnivores


Comment

  • There may be several layers of Secondary Consumers in an ecosystem.


Get their energy from the organic waste produced by all levels.

Ex: bacteria and fungi

Detritivores


Linear pathway of who eats who in an ecosystem.

Food Chain


Network showing all the feeding relationships in an ecosystem.

Food Webs


Primary Productivity

  • The rate at which light energy is captured by autotrophs or primary producers.


Primary Productivity

  • NPP = GPP - Rs

  • NPP = Net Primary Productivity

  • GPP = Gross Primary Productivity

  • Rs = Respiration


Available Energy

  • Daily - 1022 joules of solar radiation.

  • 1% - captured by Ps.

  • About 170 billion tons of organic matter is created each year.


Primary Producers

  • 50 - 90% of GPP is lost to Rs by the primary producers.

  • NPP = 10 - 50%

  • Animals - use only NPP, which limits the food webs.


Limiting Factors

  • Material or nutrient that is not present in sufficient quantity for the primary producers.

  • Ex: N, P, K, Mg Light, CO2


Energy Transfers

  • Not 100% efficient.

  • Why?

  • Second law of thermodynamics.

  • Waste.

  • Materials that can’t be digested etc.


Energy Transfer

  • Averages 10% with each Trophic Level change.


Question ?

  • Why do most ecosystems have only 3 - 4 trophic levels?

  • There isn’t enough energy passed up through the food web to support more levels.


Implications

  • There has to be fewer high level consumers in a food web.

  • The higher level consumers usually need a large geographical area.


Question

  • Which would support more humans per area?

    • Eating meat?

    • Eating plants?


Pyramids

  • Graphical representation of relationships in ecosystems.

  • Ex:

    1. Productivity

    2. Biomass

    3. Numbers


Chemical Cycling

  • Matter is recycled through ecosystems.

  • Ex: Biogeochemical Cycles


Matter Reservoirs

1. Organic Materials

2. Inorganic Materials

  • Available  Unavailable


Representative Cycles

  • Water

  • Carbon

  • Nitrogen

  • Know one or more of these cycles for an essay question.


Energy vs Matter

  • Energy - flows through ecosystems and is mostly lost as heat.

  • Matter - cycles in ecosystems.


Question ?

  • What is Man's influence on Ecosystems ?

  • Humans have had many negative impacts.


Hubbard Brook


Biological Magnification

  • The concentration of toxins in successive levels of a food web.

  • Ex: DDT Heavy metals (Hg, Cd Pb)


Causes

  • Not broken down by digestion/decomposition.

  • Lipophilic.

  • Concentrates and effects the upper levels of the food web.


Greenhouse Effects

  • The trapping of heat by the Earth's atmosphere. (CO2, H2O etc.).


Carbon Dioxide Levels

  • Prior 1850 - 274 ppm 1958 - 316 ppm 1992 - 351 ppm

  • Point: the levels of CO2 are rising. The cause is probably due to humans.


Causes

  • Industrialization.

  • Burning of fossil fuels.

  • Loss of forests.


Result

  • Earth will heat up.

  • Ice caps melt and sea levels will rise.

  • Climate shifts.

  • Increased Ps (?)


Acid Rain

  • Caused by air pollution.

  • Lowers the pH of rainfall.

  • Is seriously damaging many ecosystems.


Habitat Destruction

  • Worst problem threatening most species today.


Comment

  • Man has a major impact on the Biosphere.

  • Man needs to learn how to work with the Biosphere.


Summary

  • Know the tropic levels of ecosystems.

  • Know an example of a food chain and a food web.

  • Know how energy moves through an ecosystem.


Summary

  • Know how matter moves through an ecosystem.

  • Know one or more examples of matter cycling.

  • Be able to discuss in detail a human impact problem on ecosystems.


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