Overview of Chapter 3

Transcription

1 Overview of Chapter 3 What is Ecology? The Energy of Life Laws of Thermodynamics Photosynthesis and Cellular Respiration Flow of Energy Through Ecosystems Producers, Consumers and Decomposers Path of Energy Flow: Who Eats Whom Ecological Pyramids Ecosystem Productivity

2 Ecology Ecology logy study of, eco house study of one s house The study of interactions among and between organisms in their abiotic environment Biotic - living environment Includes all organisms Abiotic - non living or physical environment Includes living space, sunlight, soil, precipitation, etc.

3 Ecology Organisms interact with biotic components, but also effect many physical and chemical processes Physical walking on soil Chemical CO 2, O 2, wastes

4 Ecology Ecologists are interested in the levels of life above that of organism

5 Ecology Definitions Species - A group of similar organisms whose members freely interbreed to produce fertile offspring Population - A group of organisms of the same species that live in the same area at the same time Community - All the populations of different species that live and interact in the same area at the same time Ecosystem - A community and its physical (abiotic) environment Landscape - Several interacting ecosystems (ex: bear hunting for salmon in a river, living in adjacent forest)

6 Ecology Part of Earth that contains living organisms Community and physical environment All populations of species in an area Group of same species Individuals

7 Ecology Coral Reef communities similar to rainforests for number of species and productivity Threatened with changing climate How can communities be protected from warming waters? What could loss mean?

8 Ecology Biosphere contains earth s communities, ecosystems and landscapes, and includes: Atmospheregaseous envelope surrounding earth Hydrosphereearth s supply of water Lithosphere- soil and rock of the earth s crust

9 Ecology Atmosphere Lithosphere Hydrosphere

10 Energy of Life The ability or capacity to do work Chemical, Thermal, Mechanical, Nuclear, Electrical, and Radiant/Solar (below)

11 Energy of Life Solar radiation is the primary source of energy on planet Plants turn solar radiation into food

12 Energy of Life Energy exists as: Potential energy (stored energy) Kinetic energy (energy of motion) Potential energy is converted to kinetic energy as arrow is released from bow

13 Thermodynamics Study of energy and its transformations System- the object being studied Closed System- Does not exchange energy with surroundings (rare in nature) Open Systemexchanges energy with surroundings

14 Laws of Thermodynamics First Law of Thermodynamics Energy cannot be created or destroyed; it can change from one form to another Energy is absorbed by water and plate, but not lost

15 Laws of Thermodynamics Second Law of Thermodynamics When energy is converted form one form to another, some of it is degraded to heat Heat is highly entropic (disorganized) Water in sunlight will get warmer Engine converts chemical energy of gasoline into mechanical energy inefficiently

16 Photosynthesis Biological process by which energy from the sun (radiant energy) is transformed into chemical energy of carbohydrate (sugar) molecules 6 CO H 2 O + radiant energy Chlorophyll in plants C 6 H 12 O H 2 O + 6 O 2

17 Cellular Respiration The process where the chemical energy captured in photosynthesis is released within cells of plants and animals C 6 H 12 O O H 2 O 6 CO H 2 O + energy This energy is then used for biological work

18 Photosynthesis and Cellular Respiration

19 Life without Sun 1970s discovered hydrothermal vents in deep ocean (200 o C or 392 o F) Rich ecosystem supported without light Bacteria perform chemosynthesis Similar to photosynthesis, but use chemical (H 2 S) not sunlight

20 Energy Flow Through Ecosystems Passage of energy through an ecosystem

21 Food Chains- The Path of Energy Flow Energy from food passes from one organism to another based on their Trophic Level Definition: An organism s position in a food chain, which is determined by its feeding relationships First Trophic Level: Producers Second Trophic Level: Primary Consumers Third Trophic Level: Secondary Consumers Decomposers are present at all trophic levels

22 Food chains Autotrophs = Producers Auto self and tropho nourishment Produce own food from inorganic material Ex: plants via photosynthesis and hydrothermal vent bacteria via chemosynthesis

23 Food chains Heterotrophs = Consumers heter different and tropho nourishment Uses bodies of other organisms as food Omnivores eat both plants and animals

24 Food chains Consumers of detritus (detritivores) Eat dead material such as leaves, carcasses, feces Ex: crabs, worms, millipedes, snails

25 Food chains Decomposers or saprotrophs sapro rotten and tropho nourishment Breakdown dead organic material Release inorganic molecules (CO 2 and nutrients) that producers can use Ex: fungus, bacteria Involved in all aspects of food chains

26 Food Web Food web visualizes feeding relationships within a community More complex than food chain Still simplified compared to nature

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28 Humans and Antarctic food web Base of web is algae, which is eaten by krill Krill are eaten by many larger organisms Wastes of whales resupply nutrients for algae and krill Whaling can remove a critical component for decomposers Ozone layer depletion allows UV rays to destroy phytoplankton Climate change is warming the ocean, lowering ph, decreasing dissolved oxygen; altering ecosystem!

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30 Ecological Pyramids Graphically represent the relative energy value of each trophic level Important feature - large amount of energy is lost as heat between trophic levels Three main types Pyramid of numbers Pyramid of biomass Pyramid of energy

31 Pyramid of Numbers Illustrates the number of organisms at each trophic level Fewer organisms occupy each successive level q Does not indicate: biomass of organisms at each level amount of energy transferred between levels

32 Pyramid of Biomass Illustrates the total biomass at each successive trophic level q Biomass: measure of the total amount of living material q ~90% reduction in biomass through trophic levels q 100 to 10

33 Pyramid of Energy Illustrates how much energy is present at each trophic level and how much is transferred to the next level Most energy dissipates between trophic levels Lost as heat and energy to maintain each level Explains why there are so few trophic levels

34 Ecosystem Productivity Gross Primary Productivity (GPP) Total amount of energy that plants capture and assimilate in a given period of time Cellular respiration (R) Plants use some energy of GPP to maintain themselves Plants respire too Net Primary Productivity (NPP) Productivity after respiration losses are subtracted What is available as food for other organisms

35 Ecosystem Productivity GPP is similar to gross pay in paycheck R is similar to taxes NPP is similar to take home pay Net Primary Productivity (plant growth per area per time) Gross Primary Plant Cellular Productivity (total Respiration = photosynthesis per - (per area per time) area per time)

36 Variation in NPP by Ecosystem Coral reefs are near tropical rain forests Humans consume a large amount of global NPP ~30% but we make up ~0.5% of biomass This represents a threat to planet s ability to support both human and non-human inhabitants See PAGE 52 (bottom)!

37 Energy and Climate Change Humans use a large portion of global NPP If we use more biomass as energy rather than fossil fuels, our use of NPP may increase Corn as fuel, wood for heat How can we balance our needs with other organisms?