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Chapter 3 Ecosystems and Energy.

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Presentation on theme: "Chapter 3 Ecosystems and Energy."— Presentation transcript:

1 Chapter 3 Ecosystems and Energy

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 ) Levels of biological organization: Starts with the atom, which combines to form a molecule -> cells -> tissues -> organs etc.

4 What is Ecology? Ecological Levels of Organization:
Level after organism is population. Population: A group of organisms of the same species that live together in the same area at the same time Species: A group of similar organisms whose members freely interbreed with one another in the wild to produce fertile offspring 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:
Populations are organized into communities 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 processes collectively regulate global cycles of water, carbon, nitrogen, phosphorus and sulfur, which are essential to the survival of human and all other organisms Ecosystem: A community and its physical environment

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? Energy exist in different forms
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
Law of conservation of energy: energy cannot be created or destroyed, but is changed from one form to another. 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 –
Thermodynamics: The study of energy and its transformations Closed system: does not allow sunlight in Open system: radiant energy free to move back and forth

11 The Energy of Life 1st Law of Thermodynamics –
energy can change forms, but is not created or destroyed 2nd Law of Thermodynamics – “Entropy Rules!” amount of usable energy decreases as energy changes forms 1st Law deals with quantity of energy, 2nd Law with quality of energy. Entropy: A measure of the disorder or randomness in a system

12 The Energy of Life Photosynthesis 6 CO2 + 12 H2O + radiant energy
C6H12O6 + 6 H2O + 6 O2 Sugar In photosynthesis, energy from the sun is stored in plants

13 The Energy of Life Cellular Respiration C6H12O6 + 6 O2 + 6 H2O
6 CO H2O + 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 Ends with decomposers Note that energy is lost as heat

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 Baleen whales What would happen if you eliminated krill? Krill Squid Fishes During the last 150 years (until the 1986 global ban on whaling), the hunting of whales steadily reduced the number of large baleen whales in Antarctic waters. As a result of fewer whales eating krill, more krill became available for other krill-eating animals, whose populations increased. This altered the ecosystem. Now that commercial whaling is regulated, it is hope that number of large baleen whales will increase and resume their former position of dominance in terms of krill consumption. Human-related change has thinned the ozone over Antarctica allowing more of the sun’s ultraviolet radiation to penetrate the atmosphere, which may damage the algae that forms the base of the Antarctic food web. Another human induced change is global warming. As the water warms, less pack ice is available to provide the food supply for the krill. In addition, fishermen have started to harvest krill to make fishmeal for aquaculture industries. The loss of krill effects the entire Antarctic food web including the many marine animals that depend on krill for food. Toothed whales Penguins Seals

19 The Path of Energy Flow Pyramid of Numbers 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. Pyramid of Energy

22 The Path of Energy Flow Example: Thermodynamics in Action
Temperate forest: Primary producers = 1,500 g / m2 Desert: Primary producers = 100 g / m2 Food webs very complex, more tertiary consumers, some quaternary. Food webs very simple, very few tertiary consumers

23 The Path of Energy Flow Desert Biomass Pyramid such as . . .
13.5 kg coyote must range ~12 ha to subsist (30 acres). Desert Biomass Pyramid Tertiary consumers = 0.1 g / m2 Tertiary consumers must range over large areas to obtain enough energy to subsist. Secondary consumers = 1.0 g / m2 Primary consumers = 10 g / m2 Primary producers = 100 g / m2

24 The Path of Energy Flow Temperate Forest Biomass Pyramid
13.5 kg coyote only needs ~1 ha to subsist (2.5 acres). Temperate Forest Biomass Pyramid NOTE: just relative examples, not accurate Tertiary consumers = 1.5 g / m2 Secondary consumers = 15 g / m2 Primary consumers = 150 g / m2 Primary producers = 1,500 g / m2 Also, possibility of quaternary consumers, like bears.

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 ecosystem’s 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 Earth’s 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 world’s 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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