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Ecosystems and Energy Chapter 3. Ecology Study of the interactions of organisms and their living and non-living environment Many different scales to ecology.

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Presentation on theme: "Ecosystems and Energy Chapter 3. Ecology Study of the interactions of organisms and their living and non-living environment Many different scales to ecology."— Presentation transcript:

1 Ecosystems and Energy Chapter 3

2 Ecology Study of the interactions of organisms and their living and non-living environment Many different scales to ecology Abiotic factor – Non-Living environment Example: Wind, soil, precipitation Biotic factor – Living environment Example: all organisms (plants, people)

3 Organism – any living thing Species – Group of organisms who interbreed and produce fertile offspring Population – A group of organisms in the same species that live in the same area at the same time Community – All populations in the same area, at the same time that interact Ecosystem – A community together with its physical environment Landscape – several interacting ecosystems Biosphere – All living organisms on Earth Levels of Ecology

4 Biosphere - All living organisms on Earth Hydrosphere – All of Earth’s water supply Atmosphere – Gases that surround the Earth Lithosphere – Soil and rock of Earth’s crust Ecology encompasses the study of the interrelationships among Earth’s biosphere, hydrosphere, atmosphere and lithosphere

5 Energy – ability to do work Energy is the capacity to do work measured in kJ (work) or kcal (heat) Kcal = raise 1kg water 1 degree = 4.184 kJ Different forms of energy Electrical, chemical, solar, mechanical, nuclear, thermal Potential vs. Kinetic energy

6 Thermodynamics Open system – Closed system -

7 First Law of Thermodynamics Energy cannot be created or destroyed. It can be transferred from one form to another An organism cannot create the energy that it requires to live Plants Sponge Bacteria Humans

8 Second Law of Thermodynamics Whenever energy is converted from one form to another, some usable energy is lost in thermal energy that disperses into the environment Entropy – Measure of disorder or randomness Entropy tends to increase over time No energy conversion process is 100% efficient Cars = 20-30% efficient Cells = 50% efficient Order is maintained through constant energy input

9 Photosynthesis Light energy from the sun is converted to chemical energy carbohydrates (glucose) Uses photosynthetic pigments (chlorophyll) 6CO 2 + 12H 2 O + sun  C 6 H 12 O 6 + 6H 2 O + 6O 2

10 Cellular Respiration Organic molecules (glucose) are broken down to release energy Usually in the presence of water and oxygen C 6 H 12 O 6 + 6O 2 + 6H 2 O  6CO 2 + 12H 2 O + energy

11 Energy FLOW in an ecosystem Enters as solar energy (sun) Photosynthesis (plants) Stored energy (organic molecules) Cellular respiration Some lost to environment (2 nd Law of thermodynamics)

12 Roles in an ecosystem Producers/Autotrophs Consumers/Heterotrophs Primary Consumers Herbivores (omnivores ) Secondary Consumers Carnivores (omnivores) Tertiary Consumers Detritus Feeders Decomposers/Saprotrophs

13 Food chain Always linear Simplistic

14 Food Web More complex

15 Ecological Pyramid Shows relative energy values in each trophic level 10% rule

16 Pyramid of numbers Usually more producers than consumers More prey than predators

17 Pyramid of Biomass Biomass – Quantitative estimate of total mass of living material Usually in units (g/m 2 )

18 Pyramid of energy Energy content (kcal/m 2 /year) Never 100% efficient 10% Rule Usually not more than 4 or 5 trophic levels

19 Productivity of Producers Gross Primary Productivity – (GPP) Energy that is captured during photosynthesis Net Primary Productivity (NPP) Energy that remains in a plant after respiration NPP = GPP – Respiration

20 Productivity Units : kcal/m 2 /year Energy fixed by photosynthesis Grams of carbon in tissue Most productive ecosystems: Rainforests Wetlands, swamps, marshes Most unproductive ecosystems: Tundra, deserts Open ocean

21 The NPP for a particular river ecosystem is measured at 8833 kcal/m 2 /year. Respiration by the aquatic producers is estimated at 11,977 kcal/m 2 /year. Calculate the GPP for the ecosystem. NPP = GPP – R 8833 = GPP – 11,977 GPP = 8,833 + 11,977 GPP = 20,810 kcal/m 2 /year


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