1. Principles of Ecology Ch. 13

2. 13.1 Ecologists study relationships
Ecology: the study of the interactions among living things, and between living things and their surroundings.
Eco = environment
ology = study of
This is studied at different levels

3. LEVELS OF ORGANIZATION
1. organism - an individual living thing, such as an alligator.
Organism

4. LEVELS OF ORGANIZATION
2. population is a group of the same species that lives in one area.
- Several alligators living together.
Population
Organism

5. LEVELS OF ORGANIZATION
3. A community is a group of different species that live together in one area.
- Alligators, birds, fish, plants
all living together in a swamp.
Community
Population
Organism

6. LEVELS OF ORGANIZATION
4. An ecosystem includes all of the organisms as well as the non-living things such as; climate, soil, water, rocks and other in a given area.
Ecosystem
Community
Population
Organism

7. LEVELS OF ORGANIZATION
5. A biome is a major regional or global community of organisms characterized by the climate conditions and plant communities that thrive there.
Biome
Ecosystem
Community
Population
Organism

8. Ecological research methods include observation, experimentation, and modeling.
Direct surveys used for easy to spot and follow species employ binoculars or scopes.
Indirect surveys are used for species that are difficult to track and include looking for other signs of their presence.
Feces or a recent kill.

9. Counting Population Size
_____________________________________
2. _____________________________________
Quadrat Sampling
TAGGING / RADIO TELEMETRY
Mark and Recapture –
Capture a number organisms- mark/tag them
Recapture a portion
The number of marked organisms if proportional to the size of the whole population.

10. Counting Population Size
What is the population of turtles in the rectangle: _______

11. QUADRAT SAMPLING MEASURE THE SIZE OF THE SQUARE: _______________
TIME YOURSELF AND COUNT THE NUMBER OF TURTLES: ____
DETERMINE HOW MANY SQUARES CAN FIT INTO THE LARGER RECTANGLE ON THE PREVIOUS PAGE: _________
CALCULATE THE POPULATION OF TURTLES IN THE RECTANGLE: ___________________________________
Where your two numbers relatively close? _____________________
What is the advantage of quadrat sampling? _____________________
What is the disadvantage of quadrat sampling? _____________________
What type of organism do you think would be best suited for quadrat sampling? ____________________________________________________

12. Experiments: Performed in the lab or in the field.
Lab experiments:
Positive = More control
Negative = Doesn’t always reflect what happens in nature
Field experiments:
Positive = More accurate picture of what happens in nature
Negative = May not help determine cause and effect

13. Modeling:
Computer and Mathematical models
“What would happen if…”
Predict outcomes
Allows scientists to learn about organisms or ecosystems in ways that would not be possible in a natural or lab setting.

14. Section 13.1 Review
What are the five different levels of organization studied by ecologists?
2. Describe the three general methods used by ecologists to study organisms.
3. What ecological research methods would you use to study bird migration? Explain your choices.
How might an ecologist use modeling to study fire in a forest ecosystem? What might be some key variable used to create the model?

15. YES NO
BIOTIC
ABIOTIC

16. What makes up an ecosystem?
13.2 Biotic and Abiotic Factors
What makes up an ecosystem?
ALL LIVING THINGS
BACTERIA-PROTIST-FUNGUS-PLANTS-ANIMALS
BIOTIC:
ALL NON-LIVING THINGS
WATER-SUN-SNOW-CLOUDS-ROCKS-MOUNTAINS
ABIOTIC:

17. Changing one factor can affect many other factors
Biodiversity
Biodiversity is the assortment, or variety, of living things in an ecosystem.
Rainforests have more biodiversity than other locations in the world, but are threatened by human activities.
Keystone species is a species that has an unusually large effect on its ecosystem.
Example = Beaver
keystone

18. creation of
wetland
ecosystem
increased waterfowl
Population
increased fish
population
nesting sites for birds
keystone species

19. Section 13.2 Review
Select an ecosystem that is familiar to you and describe the biotic and abiotic factors that exist there.
2. How would the removal of a keystone species affect an ecosystem’s biodiversity?
3. Name an abiotic factor. Explain how a change in an abiotic factor would affect biodiversity.
Humans are sometimes described as being a keystone species. Does this label fit? Why or why not?

20. 13.3 Energy in Ecosystems`
Producers provide energy for other organisms in an ecosystem.
Producers- make their own food – also called autotrophs
Consumers – get energy by eating – also called heterotrophs
Almost all producers obtain energy from sunlight.
Photosynthesis in most producers uses sunlight as an energy source.
Chemosynthesis in prokaryote (bacteria) producers uses chemicals as an energy source.
Video clip

21. Section 13.3 Review
How does the stability of an ecosystem depend on its producers?
2. What are the two processes used by producers to obtain energy?
3. Few producers live deep below a lake’s surface. Suggest an explanation for this pattern.
Could producers survive without consumers? Explain why or why not?
5. Could consumers survive without producers? Why or why not?

22. 13.4 Food Chains and Food Web
Food chains and food webs model the flow of energy in an ecosystem.
Show feeding relationships for one chain of producers and consumers in an ecosystem
Arrow always points in the direction the energy is going.
DESERT COTTONTAIL
GRAMA GRASS
HARRIS’S HAWK

23. Consumers are not all alike.
Herbivores eat only plants.
Carnivores eat only animals.
Omnivores eat both plants and animals.
Detritivores eat dead organic matter.
Decomposers are detritivores that break down organic matter into simpler compounds.

24. Specialists are consumers that primarily eat one specific organism or a very small number of organisms.
Ex: Florida Snail Kite – eats only snails
Generalists are consumers that have a varied diet.
Ex: Grey wolf

25. Trophic Levels- Feeding levels in a food chain
Primary consumers are herbivores that eat producers.
Secondary consumers are carnivores that eat herbivores.
Tertiary consumers are carnivores that eat secondary consumers.
Omnivores, such as humans that eat both plants and animals, may be listed at different trophic levels in different food chains.

26. Food Web
Shows many interconnected food chains in an ecosystem

27. Identify three food chains from this food web.
copyright cmassengale

28. A Salt Marsh
Food Web
Name the producers in the salt marsh community. ___________________________
Name four primary consumers in the salt marsh community. __________________ ___________________ ___________________ _____________________
Name four secondary consumers in the salt marsh community. _________________ ___________________ ___________________ _____________________
Name an animal in the salt marsh community that eats both plants and animals. _________________________________________________________________
Name the two animals at the top of the salt marsh food web. _________________________________________________________________
Why are the decomposers shown as the are in this picture? __________________________________________________________________
Who is the “highest’ consumer? ________________________________

29. copyright cmassengale

30. Section 13.4 Review
Why are food chains especially useful for describing the relationships of specialists?
2. What happens to energy as it flows through a food web?
Only a small percentage of all consumers are specialists. What danger does a specialist face that a generalist does not?
How might the stability of an ecosystem be affected if all the decomposers were suddenly removed?

31. Water cycles through the environment.
The hydrologic, or water cycle is the circular pathway of water on Earth.
Organisms all have bodies made mostly of water.
precipitation
condensation
transpiration
evaporation
water storage
in ocean
surface
runoff
lake
groundwater
seepage

32. Elements essential for life also cycle through ecosystems.
A biogeochemical cycle is the movement of a chemical through the biological and geological parts of an ecosystem.
The Oxygen cycle involves photosynthesis and respiration.
Oxygen cycles indirectly through an ecosystem by the cycling of other nutrients.

33. Carbon is the building block of life.
The carbon cycle moves carbon from the atmosphere, through the food web, and returns to the atmosphere.
Carbon is emitted by the burning of fossil fuels.
Some carbon is stored for long periods of time in areas called carbon sinks.
fossil fuels
photosynthesis
carbon dioxide
dissolved in water
decomposition
of organisms
respiration
carbon
dioxide
in air
combustion

34. The nitrogen cycle mostly takes place underground.
Some bacteria convert gaseous nitrogen into ammonia through a process called nitrogen fixation.
nitrogen-fixing bacteria live in roots of plants; others live freely in the soil.
bacteria change the ammonium into nitrate.
moves through the food web and returns to the soil during decomposition.
nitrogen in
atmosphere
animals
denitrifying
bacteria
nitrifying
ammonium
ammonification
decomposers
plant
nitrogen-fixing
bacteria in soil
bacteria in roots
nitrates
nitrites

35. The phosphorus cycle takes place at and below ground level.
released by the weathering of rocks.
moves through the food web and returns to the soil during decomposition.
leaches into groundwater from the soil and is locked in sediments.
added to environment by both mining and agriculture
geologic uplifting
rain
weathering of
phosphate from rocks
runoff
sedimentation
forms new rocks
leaching
phosphate in solution
animals
plants
decomposers
phosphate
in soil

36. Section 13.5 Review
How does the hydrologic cycle move water through the environment?
What are the four elements that cycle through ecosystems and why are they important?
Why might farmers plants legumes such as peas to improve the nitrogen levels in their soil?
Explain the importance of decomposers to the overall biogeochemical cycle

37. An energy pyramid shows the distribution of energy among trophic levels.
energy transferred
energy
lost
Energy pyramids compare energy used by producers and other organisms on trophic levels.
Up to 90 percent of the energy = lost as heat between each level
Only 10 percent of the energy at each tier is transferred from one trophic level to the next.

38. Pyramids for Biomass and numbers
Biomass is a measure of the total dry mass of organisms in a given area.
tertiary
consumers
secondary
primary
producers
75 g/m2
150g/m2
675g/m2
2000g/m2

39. A pyramid of numbers shows the numbers of individual organisms at each trophic level in an ecosystem.
tertiary
consumers
secondary
primary
producers 5
5000
500,000
5,000,000
A vast number of producers are required to support even a few top level consumers.

40. Section 13.6 Review
How does an energy pyramid help to describe energy flow in a food web?
2. What is the difference between a biomass pyramid and a pyramid of numbers?
3. How would you draw a pyramid of numbers for a dog with fleas? What shape would the pyramid take?
If each level in a food chain typically loses 90% of the energy it takes in, and the producer level uses 1000 kilocalories of energy, how much of that energy is left after the third trophic level?