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Ecosystems and Energy Chapter 3. What is Ecology? Ecology – study of the interactions among organisms and between organisms (biotic) and their abiotic.

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Presentation on theme: "Ecosystems and Energy Chapter 3. What is Ecology? Ecology – study of the interactions among organisms and between organisms (biotic) and their abiotic."— Presentation transcript:

1 Ecosystems and Energy Chapter 3

2 What is Ecology? Ecology – study of the interactions among organisms and between organisms (biotic) and their abiotic environment. Biotic –Living component of the environment –Ex: birds, insects Abiotic –Nonliving or physical components of the environment Ex: light, oxygen

3 What is Ecology? Levels of Biological Organization Ecologist are most interested in the level that includes or is above an individual organism. (From elephant )

4 What is Ecology? Ecological Levels of Organization: Population: group of organisms of the same species that live together in the same area at the same time

5 What is Ecology? Ecological Levels of Organization: Community: all the populations of different species that live and interact together within an area at the same time

6 What is Ecology? Ecological Levels of Organization: Ecosystem: A community and its physical environment CO 2

7 What is Landscape Ecology? A subdiscipline that studies ecological processes that operate over large areas Landscape – encompasses larger area and several ecosystems Biosphere – the whole earth

8 The Energy of Life What is energy? –The capacity or ability to do work Energy exist in different forms –Chemical, radiant (light), thermal (heat), mechanical, nuclear, electrical Units –Kilojoules (kJ) –Kilocalories (kcal) –1 kcal = kJ

9 The Energy of Life Potential vs. Kinetic Energy This is stored energy This is the energy of motion Potential energy changed into kinetic energy when the arrow is released

10 The Energy of Life Thermodynamics –

11 The Energy of Life 1 st Law of Thermodynamics – energy can change forms, but is not created or destroyed 2 nd Law of Thermodynamics – Entropy Rules! amount of usable energy decreases as energy changes forms 1 st Law deals with quantity of energy, 2 nd Law with quality of energy.

12 The Energy of Life Photosynthesis 6 CO H 2 O + radiant energy C 6 H 12 O H 2 O + 6 O 2 Sugar In photosynthesis, energy from the sun is stored in plants

13 The Energy of Life Cellular Respiration C 6 H 12 O O H 2 O 6 CO H 2 O + energy In cellular respiration stored energy is released to do work

14 The Energy of Life Case-in-Point: Life Without the Sun This picture shows a hydrothermal vent ecosystem found at the bottom of the ocean Bacteria living in the tissue of the tube worm extract energy from hydrogen sulfide

15 The Flow of Energy Through Ecosystems Producers, Consumers, and Decomposers Energy flows from Producers To Consumers And finally to Decomposers

16 The Path of Energy Flow Food Chains – Shows the flow of energy in an ecosystem where energy from food passes from one organism to another. Starts here Note that energy is lost as heat Ends with decomposers

17 Food Webs – How is a food web different from a food chain? A more realistic model Consist of interlocking food chains Takes into account different food sources for an organism

18 The Path of Energy Flow Case-in-Point: How Humans Have Affected the Antarctic Food Web Krill Baleen whales Squid Fishes Toothed whales Seals Penguins What would happen if you eliminated krill?

19 The Path of Energy Flow Ecological Pyramids graphically represent the relative energy values of each trophic level. Pyramid of Numbers A pyramid of numbers shows the number of organisms at each trophic level in a given ecosystem. The organisms at the based of the food chain are the most abundant, and few organisms occupy each successive trophic level, giving the pyramid its shape.

20 Ecological Pyramids Pyramid of Biomass A pyramid of biomass illustrates the total biomass at each successive trophic level Biomass is a quantitative estimate of the total amount of living material and indicates the amount of fixed energy at a particular time.

21 Ecological Pyramids Pyramid of Energy A pyramid of energy illustrates the energy content of the biomass of each trophic level. These pyramids always have large energy bases and get progressively smaller through succeeding trophic levels showing that most energy dissipates into the environment when going from one trophic level to the next.

22 The Path of Energy Flow Example: Thermodynamics in Action Desert: Primary producers = 100 g / m 2 Temperate forest: Primary producers = 1,500 g / m 2 Food webs very simple, very few tertiary consumers Food webs very complex, more tertiary consumers, some quaternary.

23 The Path of Energy Flow Desert Biomass Pyramid Primary producers = 100 g / m 2 Primary consumers = 10 g / m 2 Secondary consumers = 1.0 g / m 2 Tertiary consumers = 0.1 g / m 2 Tertiary consumers must range over large areas to obtain enough energy to subsist. such as kg coyote must range ~12 ha to subsist (30 acres).

24 The Path of Energy Flow Temperate Forest Biomass Pyramid Primary producers = 1,500 g / m 2 Primary consumers = 150 g / m 2 Secondary consumers = 15 g / m 2 Tertiary consumers = 1.5 g / m kg coyote only needs ~1 ha to subsist (2.5 acres). Also, possibility of quaternary consumers, like bears. NOTE: just relative examples, not accurate

25 The Path of Energy Flow Ecosystem Productivity Net Primary Productivity Gross Primary Productivity Plant cellular respiration =

26 Net primary productivity (NPP) Plants respire to provide energy for their own use so that the energy in plant tissues after cellular respiration has occurred is the net primary productivity (NPP). The Net primary productivity represents the rate organic matter is actually incorporated into plant tissues for growth. Only the energy represented by NPP is available as food for an ecosystems consumers.

27 Gross Primary Productivity (GPP) Gross primary productivity (GPP) of an ecosystem is the rate energy is captured during photosynthesis. (Total energy) It is primary because plants occupy the first trophic level in food webs.

28 Human Impact on Net Primary Productivity Humans consume more of Earths resources than any other animal species. When both direct and indirect human impacts are accounted for, humans use 32% of the annual NPP of land-based ecosystems. Humans represent only 0.5% of the total biomass of all consumers and are in competition with other species needs for energy. Human use of so much of the worlds productivity may contribute to the loss of many species through extinction. To minimize this impact, humans must share terrestrial photosynthesis products, NPP with other organisms and control the population explosion.

29 The Path of Energy Flow Ecosystem Productivity Note that areas with more producers have a higher NPP


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